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Sample records for hot-pressed veneer products

  1. Numerical simulation of hot-pressed veneer products: Forming - Spring back – Distortion

    DEFF Research Database (Denmark)

    Ormarsson, Sigurdur; Sandberg, Dick

    2007-01-01

    Customers demand very high quality of veneered furniture products with regard to surface appearance, shape stability and stiffness. To meet these requirements, it is important to improve the manufacturing process by a better understanding of the thermo-hygro-mechanical behaviour of the individual...... veneers. During the manufacture of strongly curved products, the veneers are exposed to large membrane and bending deformations and to high pressure in the radial fibre direction. When hot-press forming is used, the veneers are also exposed to a high surface temperature during the pressing time (curing...... time). These severe conditions can result in plastic deformation perpendicular to the veneer surface as well as mechano-sorptive strains in the curved regions, since the heating can have a significant influence on the moisture distribution. How strong an influence these factors have on the distortion...

  2. A new hot pressing technique

    International Nuclear Information System (INIS)

    Carcey, J.

    1975-01-01

    An original hot pressing method which may be applied to ceramics, metals, and refractory powders is described. The products obtained are fine grained polycristalline materials, with homogeneous structure, very high density, unstrained and of very large dimensions (several square meters). This process equally applies to composite materials including powders, fibers, etc.. [fr

  3. Progress in hot pressing

    International Nuclear Information System (INIS)

    Brodhag, C.; Thevenot, F.

    1988-01-01

    An experimental technique is described to study hot pressing of ceramics under conditions of controlled temperature and pressure during both the heating and final sintering stages. This method gives a better control of the final microstructure of the material. Transformation mechanisms can be studied during initial heating stage (impurity degasing, reaction, phase transformation, mechanical behavior of intergranular phase...) using computer control and graphical data representations. Some examples will be given for different systems studied in our laboratory: B (α, β, amorphous), B 12 O 2 (reaction of B + B 2 O 3 ), Si 3 N 4 ( + additives), TiN, Al 2 O 3 + AlON,ZrC

  4. Hot-pressing steatite bodies

    International Nuclear Information System (INIS)

    Aparicio Arroyo, E.

    1967-01-01

    Requirements for some special nuclear engineering ceramic shapes are: big size, impervious, dimensional accuracy and good mechanical and dielectric properties. Limitations of te conventional methods and advantages of te hot pressing techniques for the manufacturing of these shapes are discussed. Hot pressing characteristics of a certain steatite powder are studied. Occurrence of an optimum densification temperature just above the tale decomposition range is found. Experimental data show that the height/diameter ratio of the specimen has no effect on the sintering conditions. Increasing darkness from the graphite mould is detected above the optimum temperature. The hot-pressed steatite is compared with a fired dry-pressed sample of the same composition. (Author) 13 refs

  5. Veneer-log production and receipts, North Central Region, 1976.

    Science.gov (United States)

    James E. Blyth; Jerold T. Hahn

    1978-01-01

    Shows 1976 veneer-log production and receipts by species in the Lake States (Michigan, Minnesota, and Wisconsin) and in the Central States (Illinois, Indiana, Iowa, and Missouri). Comparisons are made with similar data for 1974. Includes tables showing veneer-log production and receipts (for selected years) since 1946 in the Lake States and since 1956 in the Central...

  6. Veneer-log production and receipts, North Central Region, 1974.

    Science.gov (United States)

    James E. Blyth; Jerold T. Hahn

    1976-01-01

    Shows 1974 veneer-log production and receipts by species in the Lake States (Michigan, Minnesota, and Wisconsin) and in the Central States (Illinois, Indiana, Iowa, and Missouri). Comparisons are made with similar data for 1972. Includes tables showing veneer-log production and receipts (for selected years) since 1946 in the Lake States and since 1956 in the Central...

  7. Microplasticity in hot-pressed beryllium

    International Nuclear Information System (INIS)

    Plane, D.C.; Bonfield, W.

    1977-01-01

    Closed hysteresis loops measured in the microstrain region of hot pressed, commercially pure, polycrystalline beryllium are correlated with a dislocation - impurity atom, energy dissipating mechanism. (author)

  8. Method for hot pressing beryllium oxide articles

    Science.gov (United States)

    Ballard, Ambrose H.; Godfrey, Jr., Thomas G.; Mowery, Erb H.

    1988-01-01

    The hot pressing of beryllium oxide powder into high density compacts with little or no density gradients is achieved by employing a homogeneous blend of beryllium oxide powder with a lithium oxide sintering agent. The lithium oxide sintering agent is uniformly dispersed throughout the beryllium oxide powder by mixing lithium hydroxide in an aqueous solution with beryllium oxide powder. The lithium hydroxide is converted in situ to lithium carbonate by contacting or flooding the beryllium oxide-lithium hydroxide blend with a stream of carbon dioxide. The lithium carbonate is converted to lithium oxide while remaining fixed to the beryllium oxide particles during the hot pressing step to assure uniform density throughout the compact.

  9. Production of laminated veneer lumber LVL using veneer of Schizolobium amazonicum, Eucalyptus saligna and Pinus taeda

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2010-12-01

    Full Text Available This research evaluated the quality of laminated veneer lumber - LVL manufactured with veneers of Schizolobium amazonicum (paricá, Eucalyptus saligna and Pinus taeda. The LVL panels were manufactured in the laboratory conditions composed by seven veneers, 2,0 mm thickness, with different structural compositions, using phenol-formaldehyde resin. The veneers of Schizolobium amazonicum- paricá- were pre-classified by using stress wave machine. The veneers of Eucalyptus saligna and Pinus taeda were disposed in the face layer to reinforce the structural strength of LVL panels. The LVL quality was evaluated using glue line shear strength and static bending test (MOE and MOR, edge and flat. Grading of paricá veneers based on MOEd did not affected significantly the results of the glue line shear strength and MOE and MOR edge. For the MOE and MOR flat, the use of veneers of MOEd grade 1 contributed significantly to increasing the average values of these properties. In the same way, using the Eucalyptus saligna veneers on the face of LVL resulted in higher average values of MOE and MOR, edge and flat.

  10. Effect of hot pressing additives on the leachability of hot pressed sodium hydrous titanium oxide

    International Nuclear Information System (INIS)

    Valentine, T.M.; Sambell, R.A.J.

    1980-01-01

    Sodium hydrous titanium oxide is an ion exchange resin which can be used for immobilizing medium level waste (MLW) liquors. When hot pressed, it undergoes conversion to a ceramic. Three low melting point materials (borax, bismuth trioxide, and a mixture of PbO/CuO) were added to the (Na)HTiO and the effect that each of these had on aiding densification was assessed. Hot pressing temperature, applied pressure, and percentage addition of hot pressing aid were varied. Percentage open porosity, flexural strength, and leachability were measured. There was a linear relationship between the percentage open porosity and the logarithm of the leach rate for a constant percentage addition of each additive

  11. Vacuum hot pressing of titanium-alloy powders

    International Nuclear Information System (INIS)

    Malik, R.K.

    1975-01-01

    Full or nearly full dense products of wrought-metal properties have been obtained by vacuum hot pressing (VHP) of several prealloyed Ti--6Al--4V powders including hydride, hydride/dehydride, and rotating electrode process (REP) spherical powder. The properties of billets VHP from Ti--6Al--4V hydride powder and from hydride/dehydride powders have been shown to be equivalent. The REP spherical powder billets processed by VHP or by hot isostatic pressing (HIP) resulted in equivalent tensile properties. The potential of VHP for fabrication of near net aircraft parts such as complex fittings and engine disks offers considerable cost savings due to reduced material and machining requirements

  12. Hot pressing of B4C/SiC composites

    International Nuclear Information System (INIS)

    Sahin, F.C.; Turhan, E.; Yesilcubuk, S.A.; Addemir, O.

    2005-01-01

    B 4 C/SiC ceramic composites containing 10-20-30 vol % SiC were prepared by hot pressing method. The effect of SiC addition and hot pressing temperature on sintering behaviour and mechanical properties of hot pressed composites were investigated. Microstructures of hot pressed samples were examined by SEM technique. Three different temperatures (2100 deg. C, 2200 deg. C and 2250 deg. C) were used to optimize hot pressing temperature applying 100 MPa pressure under argon atmosphere during the sintering procedure. The highest relative density of 98.44 % was obtained by hot pressing at 2250 deg. C. However, bending strengths of B 4 C/SiC composite samples were lower than monolithic B 4 C in all experimental conditions. (authors)

  13. High density high-TC ceramic superconductors by hot pressing

    International Nuclear Information System (INIS)

    Mak, S.; Chaklader, A.C.D.

    1989-01-01

    High density and high T C superconductor specimens, YBa 2 Cu 3 O x , have been produced by hot-pressing. The factors studied are the effect of hot pressing on the density, the oxygen stoichiometry, the crystal structure, and the critical temperature. Hot pressing followed by heat treatment increased the density of the specimen to 93%. The hot pressing itself did not significantly affect the oxygen content in the specimen, and although the crystal structure appeared to be orthorhombic, the specimens were not superconducting above liquid nitrogen temperature. The superconductivity was restored after head treatment in oxygen. The highest critical temperature (T C ) of the hot pressed pellets was 82K, which was slightly lower than the T C that could be obtained with the cold pressed/sintered pellets. (6 refs., 5 figs., tab.)

  14. Fabrication of fully ceramic microencapsulated fuel by hot pressing

    International Nuclear Information System (INIS)

    Lee, H. G.; Kim, D. J; Park, J. Y.; Kim, W. J.; Lee, S. J

    2014-01-01

    Fully ceramic microencapsulated(FCM) nuclear fuel is one of the recently suggested concept to enhance stability nuclear fuel itself. The requirements to increase the accident tolerance of nuclear fuel are mainly two parts: First, the performance has to be maintained compared to the existing UO 2 nuclear fuel and zircaloy cladding system under the normal operation condition. Second, under the severe accident condition, the high temperature structural integrity has to be kept and the generation rate of hydrogen has to be decrease largely. FCM nuclear fuel consists of tristructural isotropic(TRISO) fuel particle and SiC matrix. The relative thermal conductivity of the SiC matrix as compared to UO 2 is quite good, yielding as-irradiated fuel centerline temperature compared to high temperature for the existing fuel leading to reduced stored energy in the core and reduced operational release of fission products from the fuel. Generally SiC ceramics are fabricated via liquid phase sintering due to strong covalent bonding property and low self-diffusivity coefficient. Hot pressing is very effective method to conduct sintering of SiC powder including different second phase. In this study, SiC-matrix composite including TRISO particles were sintered by hot pressing with Al 2 O 3 -Y 2 O 3 additive system. Various sintering condition were investigated to obtain high relative density above 95%. The internal distribution of TRISO particles within SiC-matrix composite was observed by x-ray radiograph. From the analysis of the cross-section of SiC-matrix composite, the fracture of TRISO particles was investigated. In order to uniform distribution of TRISO particle embedded in the SiC matrix, SiC powder overcoating is considered. SiC matrix composite including TRISO was fabricated by hot pressing. FCM pallets with full density were obtained with Al 2 O 3 -Y 2 O 3 additive system. From the microstructure image, the effect of the sintering additive contents and sintering mechanism

  15. Fabrication and properties of hot pressed bismuth tungstate

    International Nuclear Information System (INIS)

    Streicher, W.L.

    1978-01-01

    Bi 2 WO 6 is a synthetic polar material that is a possible candidate for energy conversion and detection systems. Previous research on this material has been concerned with crystal growth and sintering characteristics of polycrystalline compacts. This study involves itself with the fabrication of polycrystalline compacts by hot pressing techniques. Densities approaching theoretical crystal density were achieved by hot pressing at 850 0 C for one hour with pressures exceeding 35 MPa. Before hot pressing, the sintering range was determined by high temperature dilatometry of unfired Bi 2 WO 6 ceramics. Hot pressed discs were characterized by scanning electron microscopy, differential scanning calorimetry, and x-ray diffraction. Electrical properties were determined by dc resistivity, capacitance, and conductance measurements, ac poling, dc poling, and current-voltage measurements

  16. Dynamic Multiaxial Response of a Hot-Pressed Aluminum Nitride

    Science.gov (United States)

    2012-01-05

    Hutchinson, Adv. Appl . Mech. 29 (1992). [34] H. Ming-Yuan, J.W. Hutchinson, Int. J. Solids Struct. 25 (1989) 1053. [35] J. Salem , L. Ghosn, Int. J...Dynamic Multiaxial Response of a Hot- Pressed Aluminum Nitride by Guangli Hu, C. Q. Chen, K. T. Ramesh, and J. W. McCauley ARL-RP-0487...Laboratory Aberdeen Proving Ground, MD 21005-5066 ARL-RP-0487 June 2014 Dynamic Multiaxial Response of a Hot- Pressed Aluminum Nitride

  17. Control system for glassing hot presses

    Energy Technology Data Exchange (ETDEWEB)

    Howell, J.F.

    1984-06-13

    A software programmable control system has been developed that automates the glass fusing process used in the production of semiconductor thermopile elements. The new control system replaces an older, mostly manual, electromechanical design. This report describes the new control design and its functional features.

  18. ACTIVATED HOT PRESSING BEHAVIOR OF WC NANOPOWDERS

    Directory of Open Access Journals (Sweden)

    Edwin GEVORKYAN

    2010-06-01

    Full Text Available The questions of consolidation of nanopowders concerning hot compaction by pressing activated by electric current action are considered. Mechanisms of grain boundary creep-sliding which are sequentially prevalent in a forming of compacted structures under influence of temperature factor and in the presence of a direct electric heating are discussed. Structural-transformational sources and conditions of forming of high physical-mechanical properties of nanopowder refractory solid-state products are described.

  19. Process considerations for hot pressing ceramic nuclear waste forms

    International Nuclear Information System (INIS)

    Wilson, C.N.; Brite, D.W.

    1981-01-01

    Spray calcined simulated ceramic nuclear waste powders were hot pressed in graphite, nickel-lined graphite and ZrO 2 -lined Al 2 O 3 dies. Densification, initial off-gas, waste element retention and pellet-die interactions were evaluated. Indicated process considerations and limitations are discussed. 15 figures

  20. Nanoindentation hardness of hot-pressed boron suboxide

    International Nuclear Information System (INIS)

    Machaka, Ronald; Derry, Trevor E.; Sigalas, Iakovos

    2011-01-01

    Highlights: → The load-displacement indentation response of hot-pressed B 6 O is measured and analysed. → The nanoindentation hardness of hot-pressed boron suboxide is reported. → An approach is developed to simulate multi-cycling loading load-displacement curves. → A comprehensive model inter-comparison study of the ISE in hot-pressed B 6 O is also presented. → The fractal dimension is a better measure of ISE than the Meyer's index. - Abstract: The existence of the indentation size effect implies the absence of a single hardness value for the material under investigation especially at low applied loads. In this paper we present an investigation of the indentation size dependence behaviour of nanoindentation hardness in boron suboxide ceramic compacts prepared by uniaxial hot-pressing. Berkovich nanohardness indentations were conducted and analyzed accordingly. In addition to the ordinary Oliver and Pharr method of nanoindentation data analysis, a quantitative approach for the loading curve analysis is proposed. Using the proposed approach, the description and characterization of the observed indentation size effect through the application of the Meyer's law, and the classical and the modified proportional specimen resistance models as well as the multi-fractal scaling law was conducted and is reported. The load-independent hardness values deduced from our quantitative approach are comparable to the results calculated with conventional methods, especially with the multi-fractal scaling law.

  1. Nanoindentation hardness of hot-pressed boron suboxide

    Energy Technology Data Exchange (ETDEWEB)

    Machaka, Ronald, E-mail: Ronald.Machaka@wits.ac.za [DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, P. Bag 3, Wits, Johannesburg (South Africa); School of Chemical and Metallurgical Engineering, University of the Witwatersrand, P.O. Bag 3, Wits, Johannesburg 2050 (South Africa); Derry, Trevor E. [DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, P. Bag 3, Wits, Johannesburg (South Africa); School of Physics, University of the Witwatersrand, P.O. Bag 3, Wits, Johannesburg 2050 (South Africa); Sigalas, Iakovos [DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, P. Bag 3, Wits, Johannesburg (South Africa); School of Chemical and Metallurgical Engineering, University of the Witwatersrand, P.O. Bag 3, Wits, Johannesburg 2050 (South Africa)

    2011-07-15

    Highlights: {yields} The load-displacement indentation response of hot-pressed B{sub 6}O is measured and analysed. {yields} The nanoindentation hardness of hot-pressed boron suboxide is reported. {yields} An approach is developed to simulate multi-cycling loading load-displacement curves. {yields} A comprehensive model inter-comparison study of the ISE in hot-pressed B{sub 6}O is also presented. {yields} The fractal dimension is a better measure of ISE than the Meyer's index. - Abstract: The existence of the indentation size effect implies the absence of a single hardness value for the material under investigation especially at low applied loads. In this paper we present an investigation of the indentation size dependence behaviour of nanoindentation hardness in boron suboxide ceramic compacts prepared by uniaxial hot-pressing. Berkovich nanohardness indentations were conducted and analyzed accordingly. In addition to the ordinary Oliver and Pharr method of nanoindentation data analysis, a quantitative approach for the loading curve analysis is proposed. Using the proposed approach, the description and characterization of the observed indentation size effect through the application of the Meyer's law, and the classical and the modified proportional specimen resistance models as well as the multi-fractal scaling law was conducted and is reported. The load-independent hardness values deduced from our quantitative approach are comparable to the results calculated with conventional methods, especially with the multi-fractal scaling law.

  2. Means to rise stability of matrices for hot pressing of non-ferrous metals

    International Nuclear Information System (INIS)

    Nagajtsev, A.A.; Piguzova, D.Kh.; Vajnpres, L.V.

    1975-01-01

    The paper deals with the basic trends adopted both in the USSR and abroad with respect to the development and industrial usage of new materials for hot pressing dies. Methods of their strengthening are also indicated. The paper presents results of production tests of new die steels and refractory alloys at a number of factories processing non-ferrous metals. The problems of their wide application in this field are considered

  3. Hot pressing, strength, and fracture of calcium hexaboride

    International Nuclear Information System (INIS)

    Dutta, S.K.

    1975-01-01

    Fracture behavior and strength of hot-pressed CaB 6 were studied. The modulus of elasticity determined by attaching strain gages to the tensile surface of the bend bars to measure strain, was 55 +- 3 x 10 6 psi. The results are compared with values for other low density ceramic materials (B 4 C, SiB 6 , Be 4 B, AlB 12 ) in a table. The fracture mode was observed for both modulus of rupture and impact test specimens. Predominantly transgranular fracture, associated with distinct step cleavages is evident. Fracture origins were examined in an effort to understand the strength limiting features in hot-pressed CaB 6 specimens. Surface defects, large grain agglomerations, and isolated pore pockets were observed and varied from bar to bar; these were similar to those found in B 4 C. (U.S.)

  4. Method for hot pressing irregularly shaped refractory articles

    Science.gov (United States)

    Steinkamp, William E.; Ballard, Ambrose H.

    1982-01-01

    The present invention is directed to a method for hot pressing irregularly haped refractory articles with these articles of varying thickness being provided with high uniform density and dimensional accuracy. Two partially pressed compacts of the refractory material are placed in a die cavity between displaceable die punches having compact-contacting surfaces of the desired article configuration. A floating, rotatable block is disposed between the compacts. The displacement of the die punches towards one another causes the block to rotate about an axis normal to the direction of movement of the die punches to uniformly distribute the pressure loading upon the compacts for maintaining substantially equal volume displacement of the powder material during the hot pressing operation.

  5. Mechanical and thermophysical properties of hot-pressed SYNROC B

    International Nuclear Information System (INIS)

    Hoenig, C.L.; Newkirk, H.W.; Otto, R.A.; Brady, R.L.; Brown, A.E.; Ulrich, A.R.; Lum, R.C.

    1981-01-01

    The optimal SYNROC compositons for use with commercial waste are reviewed. Large amounts of powder (about 2.5 kg) were prepared by convention al ceramic operations to test the SYNROC concept on a processing scale. Samples, 15.2 cm in diameter, were hot pressed in graphite, and representative samples were cut for microstructural evaluations. Measured mechanical and thermophysical properties did not vary significantly as a function of sample location and were typical of titanate ceramic materials

  6. Graphite and boron carbide composites made by hot-pressing

    International Nuclear Information System (INIS)

    Miyazaki, K.; Hagio, T.; Kobayashi, K.

    1981-01-01

    Composites consisting of graphite and boron carbide were made by hot-pressing mixed powders of coke carbon and boron carbide. The change of relative density, mechanical strength and electrical resistivity of the composites and the X-ray parameters of coke carbon were investigated with increase of boron carbide content and hot-pressing temperature. From these experiments, it was found that boron carbide powder has a remarkable effect on sintering and graphitization of coke carbon powder above the hot-pressing temperature of 2000 0 C. At 2200 0 C, electrical resistivity of the composite and d(002) spacing of coke carbon once showed minimum values at about 5 to 10 wt% boron carbide and then increased. The strength of the composite increased with increase of boron carbide content. It was considered that some boron from boron carbide began to diffuse substitutionally into the graphite structure above 2000 0 C and densification and graphitization were promoted with the diffusion of boron. Improvements could be made to the mechanical strength, density, oxidation resistance and manufacturing methods by comparing with the properties and processes of conventional graphites. (author)

  7. Factors influencing the creep strength of hot pressed beryllium

    International Nuclear Information System (INIS)

    Webster, D.; Crooks, D.D.

    1975-01-01

    The parameters controlling the creep strength of hot pressed beryllium block have been determined. Creep strength was improved by a high initial dislocation density, a coarse grain size, and a low impurity content. The impurities most detrimental to creep strength were found to be aluminum, magnesium, and silicon. A uniform distribution of BeO was found to give creep strength which was inferior to a grain boundary distribution. The creep strength of very high purity, hot isostatically pressed beryllium was found to compare favorably with that of other more commonly used high temperature metals

  8. Hot pressing of uranium nitride and mixed uranium plutonium nitride

    International Nuclear Information System (INIS)

    Chang, J.Y.

    1975-01-01

    The hot pressing characteristics of uranium nitride and mixed uranium plutonium nitride were studied. The utilization of computer programs together with the experimental technique developed in the present study may serve as a useful purpose of prediction and fabrication of advanced reactor fuel and other high temperature ceramic materials for the future. The densification of nitrides follow closely with a plastic flow theory expressed as: d rho/ dt = A/T(t) (1-rho) [1/1-(1-rho)/sup 2/3/ + B1n (1-rho)] The coefficients, A and B, were obtained from experiment and computer curve fitting. (8 figures) (U.S.)

  9. Properties of hot pressed MgB2/Ti tapes

    International Nuclear Information System (INIS)

    Kovac, P.; Husek, I.; Melisek, T.; Fedor, J.; Cambel, V.; Morawski, A.; Kario, A.

    2009-01-01

    Hot axial and hot isostatic pressing was applied for single-core MgB 2 /Ti tapes. Differences in transport current density, n-exponents and critical current anisotropy are discussed and related to the grain connectivity influenced by pressing. The magnetic Hall probe scanning measurements allowed observing the isolated regions for axially hot pressed sample attributed to the longitudinally oriented cracks introduced by pressing. The highest current densities were measured for the tape subjected to hot isostatic pressing due to improved connectivity.

  10. Reduction of adhesive stain defect in flexible printed circuit board on hot pressing process: A case study of electronic component factory

    Directory of Open Access Journals (Sweden)

    Sakulkaew Srisang

    2015-03-01

    Full Text Available The objective of this research is a reduction of an adhesive stain defect in flexible printed circuit board in hot pressing process, the electronic factory. The manufacturing have been processing by sheet type of products with ninety-six pieces of flexible printed circuit boards. Causes of the problem include the before and internal hot pressing process. In process beginning times, the most right row of products between the cooling plate and the hot pressing machine has temperature 71.2◦C that is higher than glass transition temperature (Tg 60◦C. Those products’ temperature lead to evaporate a polyimide adhesive before hot pressing process beginning. The internal hot pressing process include the preheat times and the pressure time. In the preheat time the problem is a gap between lower and upper plate, was under specification (Under 1 mm and leaded to adhesive polyimide stain. In the actuality this time requires temperature and low pressure that mean a gap within 1 – 2 mm (between lower and upper plate. In pressure times the hot pressing plate surface is not flat and products are pressed by insufficient force that it lead to generate an adhesive stain on flexible printed circuit boards. That force is measured by the pre-scale paper and a result, RGB color, is provided. And then color density (From standard color sample and RGB color (From pre-scale paper is found out the relation by Photoshop program and multiple regression theory using. The formula is applied to compare with defect so as to find out the suitable color density (Defects reducing. The solving solutions is provided including the gap reduced adjustment between cooling plate and hot pressing machine before hot pressing process, the plate adjustment within specification in the preheat time and the pressing plate polishing in the pressure time. Results of study and solving are provide defect reduction from 24.4 percentage to 7.2 percentage of total study product.

  11. Preparation and microstructure of hot-pressed YIG

    International Nuclear Information System (INIS)

    Abdul Halim Shaari; Mansor Hashim; Sidek Haji Abd Aziz

    1992-01-01

    Bulk magnetic ceramics such as yttrium-iron-garnet (YIG) and nickel-zinc ferrite were prepared by the conventional-firing and hot-press techniques. Pre-sintering and sintering, both in air, were carried out at temperature ≥ 1200 0 C. Initial density and microstructural measurements show that the high density samples with uniform grain size can be readily achieved by hot-pressing. The well-defined microstructures, the high density attained. The agreement of saturation magnetization 4πMs values and the high resistivities indicated that the optimized preparation conditions for conventional firing yielded yttrium-iron-garnet of good quality. Quenched and isochronally annealed, the YIG samples were also found to retain their room-temperature saturation-magnetization and resonance linewidth values after any single heat treatment. However, the electrical resistivity and the effective linewidth clearly exhibited isochronal recovery. A possible model to explain this behaviour and its implications on microwave applications are discussed. Ferrites of the type MFe 2 O 4 where M=Mg, Mn, Co, Fe, Cu, Zn and Cd and of the type Ni1-2xSnxFe 2 O4 have also been prepared and their properties are being studied

  12. Waste treatment process by solidifying cementitious materials using hydrothermal hot-pressing

    International Nuclear Information System (INIS)

    Matsumoto, Y.; Kamakura, T.; Yamasaki, N.; Hashida, T.

    2001-01-01

    Solidification of low-level radioactive wastes containing Na 2 SO 4 with cement by hydrothermal hot-pressing (HHP) technique was examined. Relatively high mechanical strength, reduced leaching ratio of SO 3 , and higher resistance to the carbonation of the HHP product were attained in comparison with conventional concrete. The solidification by the HHP treatment may be proceeded by the rearrangement of particles and the bonding material formation among the particles by dissolution-deposition process. The possibility of developing the accelerated testing method for duration of cemented materials by hydrothermal method was discussed. (author)

  13. Techniques for hot-press-bonding dissimilar metal combinations

    International Nuclear Information System (INIS)

    Watson, R.D.

    1966-05-01

    High strength diffusionless bonds can be produced in a variety of dissimilar metal combinations by the hot press bonding technique covered by Canadian Patent application 904,548 June 6, 1964. Some of the combinations that can be joined successfully are Zircaloy-2 and 416 stainless steel, 416 stainless steel and mild steel, 1S aluminum and mild steel, Zircaloy-2 and M257 SAP, and Zircaloy-2 and 1S aluminum. Several other combinations were attempted but suitable joints could not be produced. The methods of producing the joints, the joint strength that can be developed and a discussion of some of the problems associated with making the joints are included in the report. (author)

  14. A study of pressureless microwave sintering, microwave-assisted hot press sintering and conventional hot pressing on properties of aluminium/alumina nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Abedinzadeh, Reza; Safavi, Seyed Mohsen; Karimzadeh, Fathallah [Isfahan University, Isfahan (Iran, Islamic Republic of)

    2016-05-15

    Bulk Al/4wt-%Al{sub 2}O{sub 3} nanocomposites were prepared by consolidating nanocomposite powders using pressureless microwave sintering, microwave-assisted hot press sintering and conventional hot pressing techniques. Microstructural observations revealed that the microwave-assisted hot press sintering at different sintering temperatures of 400.deg.C and 500.deg.C resulted in more densification and smaller grain size for Al/Al{sub 2}O{sub 3} nanocomposite as compared with the conventional hot pressing. Moreover, the application of pressure in microwave sintering process led to more densification and grain growth. Mechanical properties resulting from microhardness and nanoindentation tests were also compared between three-method processed samples. It was found that the microwave-assisted hot-pressed sample exhibited higher hardness and elastic modulus in comparison with microwave-sintered and conventional hot-pressed samples. The improvement in the mechanical properties can be ascribed to lower porosity of microwave-assisted hot-pressed sample.

  15. Hot pressing of B{sub 4}C/SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Sahin, F.C.; Turhan, E.; Yesilcubuk, S.A.; Addemir, O. [Ystanbul Technical University, Faculty of Chemistry and Metallurgy, Materials and Metallurgical Engineering Dept., Maslak-Ystanbul (Turkey)

    2005-07-01

    B{sub 4}C/SiC ceramic composites containing 10-20-30 vol % SiC were prepared by hot pressing method. The effect of SiC addition and hot pressing temperature on sintering behaviour and mechanical properties of hot pressed composites were investigated. Microstructures of hot pressed samples were examined by SEM technique. Three different temperatures (2100 deg. C, 2200 deg. C and 2250 deg. C) were used to optimize hot pressing temperature applying 100 MPa pressure under argon atmosphere during the sintering procedure. The highest relative density of 98.44 % was obtained by hot pressing at 2250 deg. C. However, bending strengths of B{sub 4}C/SiC composite samples were lower than monolithic B{sub 4}C in all experimental conditions. (authors)

  16. Microstructure characteristics of high borated stainless steel fabricated by hot-pressing sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xuan; Wang, Mingjia, E-mail: mingjiawangysu@126.com; Zhao, Hongchang

    2016-04-25

    The present study investigated the microstructure of powder metallurgy (P/M) high borated stainless steel through hot-pressing sintering in a temperature range of 1000–1150 °C within 30 min under 30 MPa. Microstructure and phase examinations were carried out by applying scanning electron microscope, electron backscatter diffraction and X-ray diffraction analysis. The results of as-atomized powders demonstrated that many powders kept egg-type structure with an austenite outer layer and the eutectic borides were much finer than those in traditional cast products. Microstructure studies revealed that borides suffered Ostwald ripening and were significantly influenced by the sintering temperature. Orientation maps indicated that the inter-particle contact areas consisted of equiaxed grains and the regions consisting of large elongated grains partly inherited the microstructure characteristics of as-atomized powder particles. Furthermore, the mechanisms governing the morphological changes in microstructure were discussed. - Highlights: • Near-complete densification could be obtained through hot-pressing sintering. • There was no phase transformation and present phases were M{sub 2}B and austenite. • Borides suffered Ostwald ripening and were significantly influenced by temperature. • Inter-particle contact areas consisted of equiaxed grains for recrystallization. • Deformation-free zones exhibited elongated grains for dendritic arms coarsening.

  17. Influence of Thinning and Pruning on Southern Pine Veneer Quality

    Science.gov (United States)

    Mark D. Gibson; Terry R. Clason; Gary L. Hill; George A. Grozdits

    2002-01-01

    This paper presents the effects of intensive pine plantation management on veneer yields, veneer grade distribution and veneer MOE as measured by ultrasonic stress wave transmission (Metriguard). Veneer production trials were done at a commercial southern pine plywood plant to elucidate the effects of silvicultural treatments on veneer quality, yield, and modulus of...

  18. Microstructure, hardness, corrosion resistance and porcelain shear bond strength comparison between cast and hot pressed CoCrMo alloy for metal-ceramic dental restorations.

    Science.gov (United States)

    Henriques, B; Soares, D; Silva, F S

    2012-08-01

    The purpose of this study was to compare the microstructure, hardness, corrosion resistance and metal-porcelain bond strength of a CoCrMo dental alloy obtained by two routes, cast and hot pressing. CoCrMo alloy substrates were obtained by casting and hot pressing. Substrates' microstructure was examined by the means of Optical Microscopy (OM) and by Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). Hardness tests were performed in a microhardness indenter. The electrochemical behavior of substrates was investigated through potentiodynamic tests in a saline solution (8g NaCl/L). Substrates were bonded to dental porcelain and metal-porcelain bond strength was assessed by the means of a shear test performed in a universal test machine (crosshead speed: 0.5 mm/min) until fracture. Fractured surfaces as well as undestroyed interface specimens were examined with Stereomicroscopy and SEM-EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The t-test (pmicrostructures whereas hot pressed specimens exhibited a typical globular microstructure with a second phase spread through the matrix. The hardness registered for hot pressed substrates was greater than that of cast specimens, 438±24HV/1 and 324±8HV/1, respectively. Hot pressed substrates showed better corrosion properties than cast ones, i.e. higher OCP; higher corrosion potential (E(corr)) and lower current densities (i(corr)). No significant difference was found (p<0.05) in metal-ceramic bond strength between cast (116.5±6.9 MPa) and hot pressed (114.2±11.9 MPa) substrates. The failure type analysis revealed an adhesive failure for all specimens. Hot pressed products arise as an alternative to cast products in dental prosthetics, as they impart enhanced mechanical and electrochemical properties to prostheses without compromising the metal-ceramic bond strength. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Evaluation of the use potential of nine species of genus Eucalyptus for production of veneers and plywood panels

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2013-06-01

    Full Text Available The objective of thisstudywas to evaluate the use potential of nine species of Eucalyptus for production of veneer sheets and multilaminated plywood panels. Veneers were cut using a pilot laminating lathe to a nominal thickness of 2.0 mm. Analysis included finding values of overall yield and yield according to three quality classes for the nine relevant species. Plywood panels were manufactured in a laboratory, consisting of five 2.0 mm veneer sheets which were bonded together with phenol-formaldehyde resin at a weight of 360 g/m2 (double line. The panels were compressed using a specific pressure of 10 kgf/cm2, a temperature of 140ºC and a pressing time of 10 minutes. Results indicated that, with the exception of E. phaeotricha and E. pellita, all other Eucalyptus species had above 50% average veneer yield after lamination. Results of glue line shear testing and static bending parallel and perpendicular demonstrated that species Eucalyptus grandis, Eucalyptus saligna, Eucalyptus dunnii, Eucalyptus globulus, Eucalyptus viminalis, Eucalyptus robusta and Eucalyptus pellita have great potential within the parameters of this study for use in the production of veneer sheets and plywood panels intended for outdoor use.

  20. Fabrication of dense yttrium oxyfluoride ceramics by hot pressing and their mechanical, thermal, and electrical properties

    Science.gov (United States)

    Tahara, Ryuki; Tsunoura, Toru; Yoshida, Katsumi; Yano, Toyohiko; Kishi, Yukio

    2018-06-01

    Excellent corrosion-resistant materials have been strongly required to reduce particle contamination during the plasma process in semiconductor production. Yttrium oxyfluoride can be a candidate as highly corrosion-resistant material. In this study, three types of dense yttrium oxyfluoride ceramics with different oxygen contents, namely, YOF, Y5O4F7 and Y5O4F7 + YF3, were fabricated by hot pressing, and their mechanical, thermal, and electrical properties were evaluated. Y5O4F7 ceramics showed an excellent thermal stability up to 800 °C, a low loss factor, and volume resistivity comparable to conventional plasma-resistant oxides, such as Y2O3. From these results, yttrium oxyfluoride ceramics are strongly suggested to be used as electrostatic chucks in semiconductor production.

  1. Brine migration in hot-pressed polycrystalline sodium chloride

    International Nuclear Information System (INIS)

    Biggers, J.V.; Dayton, G.O.

    1982-12-01

    This report describes experiments designed to provide data on brine migration in polycrystalline salt. Polycrystalling samples of various grain sizes, density, and purity were prepared from several commercial-grade salts by hot-pressing. Three distinct experimental set-ups were used to place salt billets in an induced thermal gradient in contact with brine source. The test designs varied primarily in the way in which the thermal gradient was applied and monitored and the way in which brine migration was determined. All migration was in enclosed vessels which precluded visual observation of brine movement through the microstructure. Migration velocities were estimated either by the timed appearance of brine at the hot face of the sample, or by determination of the penetration distance of migration artifacts in the microstructure after tests of fixed duration. For various reasons both of these methods were subject to a large degree of error. Our results suggest, however, that the migration velocity in dense polycrystalline salt may be at least an order of magnitude greater than that suggested by single-crystal experiments. Microstructural analysis shows that brine prefers to migrate along paths of high crystalline activity such as grain and subgrain boundaries and is dispersed rather quickly in the microstructure. A series of tests were performed using various types of tracers in brine in order to flag migration paths and locate brine in the microstructure more decisively. These attempts failed and it appears that only the aqueous portion of the brine moves through the microstructure with the dissolved ions being lost and replaced rather quickly. This suggests the use of deuterium as a tracer in future work

  2. Fractographical characterization of hot pressed and pressureless sintered AlN-doped ZrB{sub 2}–SiC composites

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, Zohre [Department of Materials Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of); Nayebi, Behzad [School of Materials and Metallurgy Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Young Researchers and Elite Club, Khorramabad Branch, Islamic Azad University, Khorramabad (Iran, Islamic Republic of); Shahedi Asl, Mehdi [Department of Mechanical Engineering, University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Ghassemi Kakroudi, Mahdi, E-mail: mg_kakroudi@tabrizu.ac.ir [Department of Materials Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2015-12-15

    In this paper, ZrB{sub 2}–SiC composites doped with 0–5 wt.% AlN were prepared by a low pressure hot pressing as well as a pressureless sintering methods at 1900 °C for 2 h. The influence of aluminum nitride addition on the sinterability and microstructure development of such ceramic composites was studied by a fractographical approach. The results revealed that only 1 wt.% AlN can aid the densification process of the hot pressed ceramic composite via the liquid phase sintering mechanism due to the formation of nano-scale metakaolinite spinel layers. In the pressureless sintering method, adding more AlN can increase the formation of gaseous products which raised the amount of porosities in the final microstructure. The formation of nano-graphite phase in the hot pressing process, the formation of Al{sub 2}OC in the pressureless sintering process, and the formation of BN in the both processes were disclosed by X-ray diffraction, SEM and TEM analyses. - Highlights: • The effect of AlN addition on densification of ZrB{sub 2}–SiC composites was studied. • AlN promotes the densification in hot pressed samples by liquid phase formation. • A fully dense composite was obtained by adding 1 wt.% AlN in hot pressing process. • In pressureless sintering, more AlN content intensifies the formation of porosities.

  3. Microscopic characterizations of membrane electrode assemblies prepared under different hot-pressing conditions

    International Nuclear Information System (INIS)

    Liang, Z.X.; Zhao, T.S.; Xu, C.; Xu, J.B.

    2007-01-01

    The durability of the membrane electrode assembly (MEA) for direct methanol fuel cells (DMFCs) is one of the most critical issues to be addressed before widespread commercialization of the DMFC technology. In this work, we investigated the effect of the hot-pressing duration on the performance and durability of the MEA prepared by hot-pressing technique. It was found that the 60-min hot pressing at 135 deg. C under the pressure of 4.0 MPa yielded a significantly improved MEA durability than did the 3-min hot pressing (a typical duration in practice) under the same condition, but no substantial difference was found in the cell performance of the MEAs prepared with the two different hot-pressing durations. The reason why the hot-pressing duration had no significant effect on cell performance is explained based on X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) characterizations of the changes in the physiochemical properties of MEAs and their constituent components, including the anode, cathode and Nafion membrane, before and after hot pressing with different durations

  4. Solidification of ion-exchange resins by hydrothermal hot-pressing

    International Nuclear Information System (INIS)

    Kaneko, M.

    1993-01-01

    The solidification reaction which easily occurs while continuously keeping the mixture of cation and anion exchange resins compressed under hydrothermal conditions has been demonstrated. Dehydration was considered to occur between sulphonic acid (-SO 3 H) from the cation exchange resin and quaternary ammonium [-CH 2 -N(CH 3 ) 3 OH] from anion-exchange resin-on terminal groups. The cation-and anion-exchange resins were mixed in a 1:1 weight ratio, put in a hot-pressing autoclave and compressed between pistons from the top and bottom at 600 kg cm -2 pressure. The material was continuously compressed during hydrothermal treatment at 200 kg cm -2 by a hydraulic jack and heated to a desired temperature with an induction heater. This system could be used for rapid temperature increasing up to 30 o c min -1 . The pressure and temperature were kept constant for 10 min. The autoclave was cooled to room temperature after the hydrothermal treatment. After the specimen was taken out, the ion-exchange radical reactions were estimated and the product structures were examined. The cation- and anion-exchange resin mixture was solidified. The resultant solidified body at a 300 o C reaction condition for 10 min had a 1.0 g cm -3 density and 700 kg cm -2 compressive strength, and the weight loss did not change in distilled water for 2 weeks. On the other hand, a solidification reaction did not occur at below 250 o C when only the cation or anion was solidified, but they were decomposed. These results suggest that a mixture of cation- and anion-exchange resins causes a solidification reaction under hydrothermal hot-pressing conditions at 300 o C. (author)

  5. Hot Press as a Sustainable Direct Recycling Technique of Aluminium: Mechanical Properties and Surface Integrity.

    Science.gov (United States)

    Yusuf, Nur Kamilah; Lajis, Mohd Amri; Ahmad, Azlan

    2017-08-03

    Meltless recycling technique has been utilized to overcome the lack of primary resources, focusing on reducing the usage of energy and materials. Hot press was proposed as a novel direct recycling technique which results in astoundingly low energy usage in contrast with conventional recycling. The aim of this study is to prove the technical feasibility of this approach by characterizing the recycled samples. For this purpose, AA6061 aluminium chips were recycled by utilizing hot press process under various operating temperature (T s = 430, 480, and 530 °C) and holding times (t s = 60, 90, and 120 min). The maximum mechanical properties of recycled chip are Ultimate tensile strength (UTS) = 266.78 MPa, Elongation to failure (ETF) = 16.129%, while, for surface integrity of the chips, the calculated microhardness is 81.744 HV, exhibited at T s = 530 °C and t s = 120 min. It is comparable to theoretical AA6061 T4-temper where maximum UTS and microhardness is increased up to 9.27% and 20.48%, respectively. As the desired mechanical properties of forgings can only be obtained by means of a final heat treatment, T5-temper, aging after forging process was employed. Heat treated recycled billet AA6061 (T5-temper) are considered comparable with as-received AA6061 T6, where the value of microhardness (98.649 HV) at 175 °C and 120 min of aging condition was revealed to be greater than 3.18%. Although it is quite early to put a base mainly on the observations in experimental settings, the potential for significant improvement offered by the direct recycling methods for production aluminium scrap can be clearly demonstrated. This overtures perspectives for industrial development of solid state recycling processes as environmentally benign alternatives of current melting based practices.

  6. Reduction of adhesive stain defect in flexible printed circuit board on hot pressing process: a case study of electronic component factory

    Directory of Open Access Journals (Sweden)

    Sakulkaew Srisang

    2014-09-01

    Full Text Available The objective of this research is a reduction of an adhesive stain defect in flexible printed circuit board in hot pressing process, the electronic factory. The manufacturing have been processing by sheet type of products with ninety-six pieces of flexible printed circuit boards. Causes of the problem include the before and internal hot pressing process. In process beginning times, the most right row of products between the cooling plate and the hot pressing machine has temperature 71.2◦C that is higher than glass transition temperature (Tg 60◦C. Those products’ temperature lead to evaporate a polyimide adhesive before hot pressing process beginning. The internal hot pressing process include the preheat times and the pressure time. In the preheat time the problem is a gap between lower and upper plate, was under specification(Under 1 mm and leaded to adhesive polyimide stain. In the actuality this time requires temperature and low pressure that mean a gap within 1 – 2 mm (between lower and upper plate. In pressure times the hot pressing plate surface is not flat and products are pressed by insufficient force that it lead to generate an adhesive stain on flexible printed circuit boards. That force is measured by the pre-scale paper and a result, RGB color, is provided. And then color density (From standard color sample and RGB color (From pre-scale paper is found out the relation by Photoshop program and multiple regression theory using. The formula is applied to compare with defect so as to find out the suitable color density (Defects reducing. The solving solutions is provided including the gap reduced adjustment between cooling plate and hot pressing machine before hot pressing process, the plate adjustment within specification in the preheat time and the pressing plate polishing in the pressure time. Results of study and solving are provide defect reduction from 24.4 percentage to 7.2 percentage of total study product.

  7. Structure and characteristics of the hot pressed hydroxyapatite/poly-L-lactide composite

    Directory of Open Access Journals (Sweden)

    Ignjatović Nenad L.

    2002-01-01

    Full Text Available Hydroxyapatite/poly-L-lactide (HAp/PLL composite biomaterial can be obtained by different processing methods. Three-dimensional blocks of HAp/PLLA composite biomaterial with mechanical characteristics close to the natural bone tissue can be obtained by hot pressing procedure. Effects of synthesis and compacting on the structure and characteristics of the HAp/PLLA composite biomaterial were studied in this work. Using wade angle X-ray structural analyses (WAXS, differentially scanning calorimetry (DSC, thermogravimetric analysis (TGA and infrared (IR spectroscopy, the changes occurring in the material during synthesis and hot pressing were monitored. Surface microstructure was analyzed by scanning electronic microscopy (SEM coupled with electron-dispersion analysis (EDX. The results obtained indicate a possible decrease in the degree of crystallinity with hot pressing time increase. A block of HAp/PLLA composite biomaterial with 1.6 times lower crystallinity of the polymer phase was obtained by hot pressing in a given time interval with a maximum of 60 minutes. Results of TG analysis show that PLLA stability decreases with increasing hot pressing time, and vice versa. IR study proved that neither destructive changes in constituents nor formation of new phases occurred during hot pressing.

  8. Microstructural analysis of hot press formed 22MnB5 steel

    Science.gov (United States)

    Aziz, Nuraini; Aqida, Syarifah Nur; Ismail, Izwan

    2017-10-01

    This paper presents a microstructural study on hot press formed 22MnB5 steel for enhanced mechanical properties. Hot press forming process consists of simultaneous forming and quenching of heated blank. The 22MnB5 steel was processed at three different parameter settings: quenching time, water temperature and water flow rate. 22MnB5 was processed using 33 full factorial design of experiment (DOE). The full factorial DOE was designed using three factors of quenching time, water temperature and water flow rate at three levels. The factors level were quenching time range of 5 - 11 s, water temperature; 5 - 27°C and water flow rate; 20 - 40 L/min. The as-received and hot press forming processed steel was characterised for metallographic study and martensitic structure area percentage using JEOL Field Emission Scanning Electron Microscopic (FESEM). From the experimental finding, the hot press formed 22MnB5 steel consisted of 50 to 84% martensitic structure area. The minimum quenching time of 8 seconds was required to obtain formed sample with high percentage of martensite. These findings contribute to initial design of processing parameters in hot press forming of 22MnB5 steel blanks for automotive component.

  9. Hot pressing of nanocrystalline tantalum using high frequency induction heating and pulse plasma sintering

    Science.gov (United States)

    Jakubowicz, J.; Adamek, G.; Sopata, M.; Koper, J. K.; Siwak, P.

    2017-12-01

    The paper presents the results of nanocrystalline powder tantalum consolidation using hot pressing. The authors used two different heating techniques during hot pressing: high-frequency induction heating (HFIH) and pulse plasma sintering (PPS). A comparison of the structure, microstructure, mechanical properties and corrosion resistance of the bulk nanocrystalline tantalum obtained in both techniques was performed. The nanocrystalline powder was made to start from the microcrystalline one using the high-energy ball milling process. The nanocrystalline powder was hot-pressed at 1000 °C, whereas, for comparison, the microcrystalline powder was hot pressed up to 1500 °C for proper consolidation. The authors found that during hot pressing, the powder partially reacts with the graphite die covered by boron nitride, which facilitated punches and powder displacement in the die during densification. Tantalum carbide and boride in the nanocrystalline material was found, which can improve the mechanical properties. The hardness of the HFIH and PPS nanocrystalline tantalum was as high as 625 and 615 HV, respectively. The microstructure was more uniform in the PPS nanomaterial. The corrosion resistance in both cases deteriorated, in comparison to the microcrystalline material, while the PPS material corrosion resistance was slightly better than that of the HFIH one.

  10. Hot-pressing steatite bodies; Obtencion de eseatita por prensado en caliente

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio Arroyo, E

    1967-07-01

    Requirements for some special nuclear engineering ceramic shapes are: big size, impervious, dimensional accuracy and good mechanical and dielectric properties. Limitations of te conventional methods and advantages of te hot pressing techniques for the manufacturing of these shapes are discussed. Hot pressing characteristics of a certain steatite powder are studied. Occurrence of an optimum densification temperature just above the tale decomposition range is found. Experimental data show that the height/diameter ratio of the specimen has no effect on the sintering conditions. Increasing darkness from the graphite mould is detected above the optimum temperature. The hot-pressed steatite is compared with a fired dry-pressed sample of the same composition. (Author) 13 refs.

  11. Radiophase development in hot-pressed alkoxide-derived titanate ceramics for nuclear waste stabilization

    International Nuclear Information System (INIS)

    Dickson, F.J.; Mitamura, H.; White, T.J.

    1989-01-01

    This paper reports phase development as a function of hot-pressing temperature studied in alkoxide-derived titanate-based ceramics doped with a 10 wt% loading of a sodium-rich (NAR) and a sodium-poor (NAP) simulated high-level waste. Pyrochlore was found to be the most abundant phase in both calcine powders. A pseudobrookite phase existed metastably at hot-pressing temperatures between 890 degrees and 920 degrees C. After hot-pressing at 1100 degrees C, the final phase assemblage for the NAP material consisted of zirconolite, hollandite-type, perovskite, alloy, and reduced rutile (Magneli phases). In addition, NAR samples contained hibonite, freudenbergite, and loveringite. Phase development was driven to completion over a very narrow temperature range (≤50 degrees C), beginning at 870 degrees and 850 degrees C for NAP and NAR, respectively, although full densification was not achieved below 1100 degrees C. Both waste forms exhibited comparable microstructure and aqueous durability

  12. Preparation of Ti-aluminide reinforced in situ aluminium matrix composites by reactive hot pressing

    International Nuclear Information System (INIS)

    Roy, D.; Ghosh, S.; Basumallick, A.; Basu, B.

    2007-01-01

    Aluminium based metal matrix composites reinforced with in situ Ti-aluminide and alumina particles were prepared by reactive hot pressing a powder mix of aluminium and nanosized TiO 2 powders. The reinforcements were formed in situ by exothermal reaction between the TiO 2 nano crystalline powder and aluminium. The thermal characteristics of the in situ reaction were studied with the aid of Differential scanning calorimetry (DSC). X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS) and Scanning electron microscopy (SEM) techniques were employed to study the microstructural architecture of the composites as a function of hot pressing temperature and volume percent reinforcement. Microhardness measurements on the as prepared in situ aluminium matrix composites exhibit significant increase in hardness with increase in hot pressing temperature and volume fraction of reinforcement

  13. Solidification of glass powder by a hydrothermal hot-pressing technique

    International Nuclear Information System (INIS)

    Nishioka, Mamoru; Yanagisawa, Kazumichi; Yamasaki, Nakamichi

    1986-01-01

    A borosilicate glass powder was solidified with a NaOH solution or distilled water by the hydrothermal hot-pressing technique. The effect of hydrothermal conditions on the compressive strength was investigated, and the densification mechanism of the glass powder during the hydrothermal hot-pressing was discussed in terms of isothermal shrinkage. The glass powder was successfully solidified by hydrothermal hot-pressing at a reaction temperature lower than that of an ordinary pressure sintering. The solidified body obtained in the presence of distilled water (10 wt%) at 280 deg C had a high compressive strength of about 2300 kg/cm 2 . The analysis of initial densification process of the glass powder in hydrothermal hot-pressing with Murray's rate equation revealed that the densification proceeds both by viscous flow and by rearrangement process. Analysis of the shrinkage rates with a rate equation of hydrothermal reaction suggested that the dissolution of particles into solution controlled the initial densification of the glass powder, and that the alkaline metal acted as a catalyst. (author)

  14. Safe trapping of cesium into pollucite structure by hot-pressing method

    International Nuclear Information System (INIS)

    Omerašević, Mia; Matović, Ljiljana; Ružić, Jovana; Golubović, Željko; Jovanović, Uroš; Mentus, Slavko; Dondur, Vera

    2016-01-01

    A simple one-step method with direct thermal conversion at lower temperatures for preparing a stabile Cs-aluminsilicate phase, known as pollucite, is presented. Cs-exchanged form of Na, Ca-LTA type of zeolite (Cs-LTA) was pressureless sintered and hot pressed at certain temperatures in order to obtain pollucite. XRD and FTIR analysis were used to study structural changes of Cs-LTA before and after thermal treatments. Pressureless sintered sample recrystallized into pollucite phase after heat treatment at 1000 °C (3 h) (PLS1000) and hot pressed sample at 750 °C (3 h) using pressure of 35 MPa (HP750), indicating reduced temperature of 250°. SEM micrographs confirmed that HP750 has higher density than PLS1000 which leads to higher value of compressive strength. The HP750 showed better resistance to Cs leaching than the PLS1000. Base on these results one can conclude that hot pressing is the promising method for the permanent disposal of Cs radionuclides. - Highlights: • Na, Ca-LTA zeolite showed high affinity for Cs ions. • Pollucite phase was obtained using hot pressing at temperature as low as ​750 °C. • HP750 shows better mechanical and morphological properties than PLS1000. • HP750 has lower leaching rate of Cs ions than PLS1000.

  15. An overview of high thermal conductive hot press forming die material development

    Directory of Open Access Journals (Sweden)

    A.R. Zulhishamuddin

    2015-12-01

    Full Text Available Most of the automotive industries are using high strength steel components, which are produced via hot press forming process. This process requires die material with high thermal conductivity that increases cooling rate during simultaneous quenching and forming stage. Due to the benefit of high quenching rate, thermal conductive die materials were produced by adding carbide former elements. This paper presents an overview of the modification of alloying elements in tool steel for high thermal conductivity properties by transition metal elements addition. Different types of manufacturing processes involved in producing high thermal conductive materials were discussed. Methods reported were powder metallurgy hot press, direct metal deposition, selective laser melting, direct metal laser sintering and spray forming. Elements likes manganese, nickel, molybdenum, tungsten and chromium were proven to increase thermal conductivity properties. Thermal conductivity properties resulted from carbide network presence in the steel microstructure. To develop feasible and low cost hot press forming die material, casting of Fe-based alloy with carbide former composition can be an option. Current thermal conductivity properties of hot press forming die material range between 25 and 66 W/m.K. The wide range of thermal conductivity varies the mechanical properties of the resulting components and lifetime of HPF dies.

  16. Effect of Hot-Pressing Temperature on the Subsequent Enzymatic Saccharification and Fermentation Performance of SPORL Pretreated Forest Biomass

    Science.gov (United States)

    Jingzhi Zhang; Andrea Laguna; Craig Clemons; Michael P. Wolcott; Rolland Gleisner; J.Y. Zhu; Xu Zhang

    2015-01-01

    Methods to increase the energy density ofbiofuel feedstock for shipment are important towards improving supply chain efficiency in upstream processes. Towards this end, densified pretreated lignocellulosic biomass was produced using hot-pressing. The effects offiber hornification induced by hot-pressing on enzymatic digestibilities of lodgepolepine and poplar NE222...

  17. Consolidation of titanium matrix composites to maximum density by different hot pressing techniques

    International Nuclear Information System (INIS)

    Montealegre Melendez, I.; Neubauer, E.; Danninger, H.

    2010-01-01

    In this present work, TiMMCs were manufactured through conventional and inductive hot pressing techniques. The starting materials were two titanium based powders as metal matrices, and two types of reinforcements, carbon nanofibres and nano-micro-boron particles. After several manufacturing runs with varying parameters, especially, optimized hot pressing parameters, the titanium compacts were characterized. Density and hardness measurements, chemical analyses and microstructural studies were conducted. The two objectives of this work were achieved. On one hand the influence, in the properties of TiMMCs, of the starting materials as matrix powder and reinforcements was determined. Higher content of impurities from the starting materials affected the hardness and the microstructure of the composites, independently of the manufacturing process. On another hand, the study of variations of the manufacturing process as temperature of consolidation and soaking time was reported. Higher densification was obtained at higher consolidation temperature; however, reaction between the matrix and the carbonaceous reinforcement was detected.

  18. Thermoelectric Properties of Hot-Pressed and PECS-Sintered Magnesium-Doped Copper Aluminum Oxide

    Science.gov (United States)

    Liu, Chang; Morelli, Donald T.

    2011-05-01

    Copper aluminum oxide (CuAlO2) is considered as a potential candidate for thermoelectric applications. Partially magnesium-doped CuAlO2 bulk pellets were fabricated using solid-state reactions, hot-pressing, and pulsed electric current sintering (PECS) techniques. X-ray diffraction and scanning electron microscopy were adopted for structural analysis. High-temperature transport property measurements were performed on hot-pressed samples. Electrical conductivity increased with Mg doping before secondary phases became significant, while the Seebeck coefficient displayed the opposite trend. Thermal conductivity was consistently reduced as the Mg concentration increased. Effects of Mg doping, preparation conditions, and future modification on this material's properties are discussed.

  19. Room temperature nanoindentation creep of hot-pressed B{sub 6}O

    Energy Technology Data Exchange (ETDEWEB)

    Machaka, Ronald, E-mail: RMachaka@csir.co.za [Light Metals, Materials Science and Manufacturing, Council for Scientific and Industrial Research, Office F7, Building 14F, P.O. Box 395, Pretoria 0001 (South Africa); DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050 (South Africa); Derry, Trevor E. [DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050 (South Africa); School of Physics, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050 (South Africa); Sigalas, Iakovos [DST/NRF Centre of Excellence in Strong Materials, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050 (South Africa); School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050 (South Africa)

    2014-06-01

    Nanoindentation has become a widely used and versatile means of characterising the near-surface nanomechanical properties of a wide variety of materials. Yet, the nanomechanical properties of the polycrystalline boron suboxide (B{sub 6}O) material prepared by uniaxial hot-pressing are sparsely known. We recently reported on the nanoindentation profiles, nanoindentation hardness, and elastic modulus determined by using the Oliver–Pharr method. To complement our earlier reports on the analysis of the load–displacement indentation response of hot-pressed B{sub 6}O and for the first time, we present and discuss results giving an insight into the temporal evolution of the nanoindentation creep behaviour in B{sub 6}O ceramics.

  20. Oxide formation and precipitation behaviors on interface of F82H steel joints during HIPing and hot pressing

    International Nuclear Information System (INIS)

    Kishimoto, H.; Ono, T.; Sakasegawa, H.; Tanigawa, H.; Ando, M.; Shibayama, T.; Kohno, Y.; Kohyama, A.

    2013-01-01

    Joining technologies for F82H steels are important issues for the development of fusion energy. The hot isostatic pressing (HIP) method is appropriate for consolidating the first wall of the blanket because of the flexibility of the shape of HIPed products. The HIP method is planned for fabricating a complex-shaped first wall component with built-in cooling channels; thus, accumulation of studies of microstructural and mechanical property changes, especially lower toughness of the HIPed joints, is essential. Present research aims to reveal the microstructural evolution of F82H joints fabricated by the HIP method compared with joints fabricated by hot pressing, focusing on the formation of oxides on the interface. F82H joints were characterized using 1/3-scale Charpy V-notch impact test, transmission electron microscope, scanning electron microscope, and electron probe analysis to survey the microstructural characteristics of the interface

  1. Densification and Grain Growth in Polycrystalline Olivine Rocks Synthesized By Evacuated Hot-Pressing

    Science.gov (United States)

    Meyers, C. D.; Kohlstedt, D. L.; Zimmerman, M. E.

    2017-12-01

    Experiments on laboratory-synthesized olivine-rich rocks form the starting material for many investigations of physical processes in the Earth's upper mantle (e.g., creep behavior, ionic diffusion, and grain growth). Typically, a fit of a constitutive law to experimental data provides a description of the kinetics of a process needed to extrapolate across several orders of magnitude from laboratory to geological timescales. Although grain-size is a critical parameter in determining physical properties such as viscosity, broad disagreement persists amongst the results of various studies of grain growth kinetics in olivine-rich rocks. Small amounts of impurities or porosity dramatically affect the kinetics of grain growth. In this study, we developed an improved method for densifying olivine-rich rocks fabricated from powdered, gem-quality single crystals that involves evacuating the pore space, with the aim of refining measurements of the kinetics of mantle materials. In previous studies, olivine powders were sealed in a metal can and hydrostatically annealed at roughly 300 MPa and 1250 °C. These samples, which appear opaque and milky-green, typically retain a small amount of porosity. Consequently, when annealed at 1 atm, extensive pore growth occurs, inhibiting grain growth. In addition, Fourier-transform infrared and confocal Raman spectroscopy reveal absorption peaks characteristic of CO2 in the pores of conventionally hot-pressed material. To avoid trapping of adsorbed contaminants, we developed an evacuated hot-pressing method, wherein the pore space of powder compacts is vented to vacuum during heating and pressurization. This method produces a highly dense, green-tinted, transparent material. No CO2 absorptions peaks exist in evacuated hot-pressed material. When reheated to annealing temperatures at 1 atm, the evacuated hot-pressed material undergoes limited pore growth and dramatically enhanced grain-growth rates. High-strain deformation experiments on

  2. Immobilisation of 137Cs and 90Sr in hot-pressed clinoptilolite

    International Nuclear Information System (INIS)

    Briggs, A.; Jones, D.V.C.; Cole, G.B.; Valentine, T.M.; Preston, R.F.; Hawes, R.W.M.; Fones, M.D.

    1984-07-01

    It is shown that clinoptilolites from Nevada and Mudhills, California, can be vitrified by hot-pressing at 1000 to 1050 deg C for 30 min under 23 MPa pressure in graphite dies, or for 10 min under 3.5 MPa pressure in stainless steel bellows-shaped containers. Activity measurements before and after hot-pressing show that the radionuclides 137 Cs and 90 Sr are retained almost completely during the process. The hot-pressed material is shown to be extremely resistant to leaching of the nuclides, either in Soxhlet or long-term static leach tests. Gamma-irradiation increases their leachability; that of 90 Sr more than that of 137 Cs, but even so, the leach rates of both remain very low. X-ray diffraction spectra taken before and after heat-treatment for 10 days at temperatures up to 1000 deg C show no deleterious effects, and hydrothermal treatments at temperatures up to 90 deg C for 100 days, even in the presence of sodium ions in solution, are shown not to cause any changes detectable by X-ray diffraction. (author)

  3. Efficient transfer of large-area graphene films onto rigid substrates by hot pressing.

    Science.gov (United States)

    Kang, Junmo; Hwang, Soonhwi; Kim, Jae Hwan; Kim, Min Hyeok; Ryu, Jaechul; Seo, Sang Jae; Hong, Byung Hee; Kim, Moon Ki; Choi, Jae-Boong

    2012-06-26

    Graphene films grown on metal substrates by chemical vapor deposition (CVD) method have to be safely transferred onto desired substrates for further applications. Recently, a roll-to-roll (R2R) method has been developed for large-area transfer, which is particularly efficient for flexible target substrates. However, in the case of rigid substrates such as glass or wafers, the roll-based method is found to induce considerable mechanical damages on graphene films during the transfer process, resulting in the degradation of electrical property. Here we introduce an improved dry transfer technique based on a hot-pressing method that can minimize damage on graphene by neutralizing mechanical stress. Thus, we enhanced the transfer efficiency of the large-area graphene films on a substrate with arbitrary thickness and rigidity, evidenced by scanning electron microscope (SEM) and atomic force microscope (AFM) images, Raman spectra, and various electrical characterizations. We also performed a theoretical multiscale simulation from continuum to atomic level to compare the mechanical stresses caused by the R2R and the hot-pressing methods, which also supports our conclusion. Consequently, we believe that the proposed hot-pressing method will be immediately useful for display and solar cell applications that currently require rigid and large substrates.

  4. EFFECT OF CHEMICAL MODIFICATION AND HOT-PRESS DRYING ON POPLAR WOOD

    Directory of Open Access Journals (Sweden)

    Guo-Feng Wu

    2010-11-01

    Full Text Available Urea-formaldehyde prepolymer and hot-press drying were used to improve the properties of poplar wood. The wood was impregnated with the prepolymer using a pulse-dipping machine. The impregnated timbers were compressed and dried by a multilayer hot-press drying kiln. The drying rate was more rapid during the chemical modification and hot-press drying than conventional kiln-drying. In addition, the properties of timber were also enhanced obviously. When the compression rate was 28.6%, the basic density, oven dry density and air-dried density of modified wood improved 22%, 71%, and 70%, respectively. The bending strength and compressive strength parallel to grain increased 60% and 40%. The water uptake of treated wood was significantly decreased compared with the untreated wood. The FTIR analysis successfully showed that the intensity of hydroxyl and carbonyl absorption peaks decreased significantly, which was attributed to a reaction of the NHCH2OH of urea-formaldehyde prepolymer with the wood carboxyl (C=O and hydroxyl (-OH groups. The XRD results indicated that the degree of crystallinity increased from 35.09% to 36.91%. The morphologic models of chemical within wood were discovered by SEM.

  5. The fabrication of ZnO nanowire field-effect transistors combining dielectrophoresis and hot-pressing

    International Nuclear Information System (INIS)

    Chang, Y-K; Chau-N H, Franklin

    2009-01-01

    Zinc oxide nanowire field-effect transistors (NW-FETs) were fabricated combining the dielectrophoresis (DEP) and the hot-pressing methods. DEP was used to position both ends of the nanowires on top of the source and the drain electrodes, respectively. Hot-pressing of nanowires on the electrodes was then employed to ensure good contacts between the nanowires and the electrodes. The good device performance achieved with our method of fabrication indicates that DEP combined with hot-pressing has the potential to be applied to the fabrication of flexible electronics on a roll-to-roll basis.

  6. Chemical vapor deposition of tantalum on graphite cloth for making hot pressed fiber reinforced carbide-graphite composite

    International Nuclear Information System (INIS)

    Hollabaugh, C.M.; Davidson, K.V.; Radosevich, C.L.; Riley, R.E.; Wallace, T.C.

    1977-01-01

    Conditions for the CVD of a uniform coating of Ta on fibers of a woven graphite cloth were established. The effect of gas composition, pressure, and temperature were investigated, and the conditions that gave the desired results are presented. Several layers of the coated cloth were hot pressed to produce a TaC--C composite having uniformly dispersed, fine-grained TaC in graphite. Three compositions were hot pressed: 15, 25, and 40 volume percent carbide. 8 figures, 2 tables

  7. Room temperature nanoindentation creep of hot-pressed B6O

    CSIR Research Space (South Africa)

    Machaka, R

    2014-06-01

    Full Text Available of the nanoindentation creep behavior in B6O ceramics. 1 Room temperature nanoindentation creep of hot-pressed B6O Ronald Machakaa,b,* , Trevor E. Derryb,d, Iakovos Sigalasb,c aLight Metals, Materials Science and Manufacturing, Council for Scientific..., University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050, South Africa dSchool of Physics, University of the Witwatersrand, Private Bag 3, Wits, Johannesburg 2050, 2050 South Africa Abstract: Nanoindentation has become a widely...

  8. Texture studies of hot-pressed K2Pb4Nb10O30 ceramics

    International Nuclear Information System (INIS)

    Filip'ev, V.S.; Zav'yalov, V.P.; Bunina, O.A.; Gavrilyachenko, S.V.; Fesenko, E.G.

    1984-01-01

    An X-ray diffraction analysis was used to investigate the texture in sampl es of K 2 Pb 4 Nb 10 O 30 ferroelectric produced by powder hot pressing and sintering at 1370-1500 k. A spontaneous formation of the secondary texture during ferroelectric phase transformation was revealed. An important role of internal stresses in the secondary texture formation was supported. The ceramic s with a high-grade texture is noted to be characterized by a high anisotropy of dielectric and piezoelectric properties, its parameters approaching to those of a monocrystal

  9. Ultra-low thermal conductivities of hot-pressed attapulgite and its potential as thermal insulation material

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuan; Ren, Zhifeng, E-mail: bohr123@163.com, E-mail: zren@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Wang, Xiuzhang [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology and School of Physics and Electronic Science, Hubei Normal University, Huangshi, Hubei 435002 (China); Wang, Yumei [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Tang, Zhongjia; Makarenko, Tatyana; Guloy, Arnold [Department of Chemistry, University of Houston, Houston, Texas 77204 (United States); Zhang, Qinyong, E-mail: bohr123@163.com, E-mail: zren@uh.edu [Center for Advanced Materials and Energy, Xihua University, Chengdu, Sichuan 610039 (China)

    2016-03-07

    In the past, there have been very few reports on thermal properties of attapulgite which is a widely used clay mineral. In this work, we report on extremely low thermal conductivities in attapulgite samples synthesized by hot-pressing. Attapulgite powder was hot-pressed at different temperatures into bulk samples, and a systematic study was conducted on the microstructures and thermal properties. Differential scanning calorimetry analysis shows that hot-pressing induces a rapid dehydration of the attapulgite powders. X-ray diffraction data and scanning/transmission electron microscopy reveal that the hot-pressed attapulgite features high porosity and complex microstructures, including an amorphous phase. As a result, the hot-pressed attapulgite exhibits thermal conductivity less than 2.5 W m{sup −1} K{sup −1} up to 600 °C. For one sample with porosity of 45.7%, the thermal conductivity is as low as 0.34 W m{sup −1} K{sup −1} at 50 °C. This suggests the potential of hot-pressed attapulgite as a candidate for thermal barrier materials.

  10. Properties of nonvolatile and antibacterial bioboard produced from bamboo macromolecules by hot pressing

    Directory of Open Access Journals (Sweden)

    Shengbo Ge

    2018-03-01

    Full Text Available Employing the antibacterial property of industrial bamboo vinegar (IBV and the photocatalytic degradation of TiO2, bamboo macromolecules were pretreated and processed into nonvolatile and antibacterial bio board (NVABB. The NVABB was then analyzed by conducting Fourier-transform infrared spectroscopy, thermogravimetric analysis and differential thermal analysis. Results show that NVABB samples had average density of 0.96 g/cm3, which is appropriate for application. In terms of physical and mechanical properties, the best NVABB sample obtained from IBV, TiO2 and bamboo had an IBV pretreatment time of 10 min, 2% TiO2 and 1% bamboo charcoal. Fourier-transform infrared spectroscopy demonstrated that optimum conditions for hot pressing were a temperature of 170 °C, duration of 15 min and the addition of IBV and TiO2. Thermogravimetric analysis/differential thermal analysis curves suggest that the thermal degradation of NVABB was less than that of bamboo and that hot pressing obviously increased the thermal stability of HDBB samples. Analysis of the antimicrobial effect revealed that IBV pretreatment improves the antibacterial property of NVABB. Keywords: Industrial bamboo vinegar, Nonvolatile and antibacterial bio board, Bamboo macromolecules, Fourier-transform infrared spectroscopy, Thermogravimetric analysis/differential thermal analysis

  11. Mechanical properties of hot-pressed Al-4.5 wt. % Cu/WC composite

    Directory of Open Access Journals (Sweden)

    Samaneh Bernoosi

    2014-12-01

    Full Text Available In this study, the elemental powders of aluminum and copper were initially subjected to mechanical alloying using an attrition ball mill under argon atmosphere to produce an Al-4.5 wt% Cu powder alloy. The WC nanoparticles were then added to the powder alloy and milled in a planetary ball mill to explore the role of the WC nanoparticles on the mechanical properties of the fabricated composite powder. The experimental results revealed that a solid solution of Al-Cu could be formed after MA and a good dispersion of the WC nanoparticles in the aluminum matrix was obtained as characterized using X-ray diffraction and scanning electron microscopy, respectively. The results of hardness and compression tests of the hot pressed composites indicated that the MA followed by the hot-press processes was successful to fabricate an alloy and a metal matrix composite with considerable mechanical properties. However, a decreasing trend in the hardness and strength of the composites with the WC contents of more than 5wt% was observed. The maximum values of 260 HV and 575 MPa were obtained for a composite containing 5 wt% of nano ceramic particles.

  12. Fabrication of laminated ZrC-SiC composite by vacuum hot-pressing sintering

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    Yuanyuan Li

    2015-03-01

    Full Text Available Laminated ZrC-SiC ceramic was prepared through tape casting and hot pressing. The green tapes of ZrC and SiC were prepared at room temperature. In order to improve the density of composite, the binder of green tapes were removed at 550 °C for 1 h. The laminated structure and the cracks propagation path, which is not a straight line, are observed by optical metalloscope. The compact laminated ZrC-SiC composite sintered by vacuum hot-pressing at 1650 °C for 90 min under pressure of 20 MPa was researched by X-ray diffraction and scanning electron microscopy (SEM equipped with energy dispersive X-ray analysis. The results showed that interlayer bonding is tight, and no disordered phase has formed in the interlayers of ZrC or SiC, and the combination mode is physical mechanism.

  13. Microstructural evolution during hot pressing of the blended elemental Ti-6%Al-7%Nb alloy

    International Nuclear Information System (INIS)

    Henriques, V.A.R.; Sandim, H.R.Z.; Coelho, G.C.; Silva, C.R.M. da

    2003-01-01

    The Ti-6%Al-7%Nb (wt.%) α-β alloy was developed aiming the replacement of the traditional Ti-6%Al-4%V alloy in surgical implants owing to its larger biocompatibility. Samples of this alloy were obtained using the blended elemental (BE) technique. The isochronal hot pressing of the compacts was carried out in the range 700-1500 deg. C with a compaction pressure of 20 MPa and a heating rate of 20 deg. C min -1 . In this work, the behavior of the elementary powders during the hot pressing and the corresponding microstructural evolution were investigated. The alloy was characterized by means of scanning electron microscopy (SEM) in the backscattered mode (BSE), X-ray diffraction (XRD), and density measurements. The results indicate that the homogenization of the alloy is diffusion-controlled and Ti.Al intermediary compounds (TiAl and Ti 3 Al) are formed at lower temperatures. With increasing temperature, homogenization of the alloy takes place and a coarse plate-like α+intergranular β structure is found throughout the microstructure in temperatures above 1300 deg. C. The process variables were defined aiming to minimize interstitial pick-up (C, O, and N) and avoiding intensive grain growth

  14. Mechanical properties and porosity of dental glass-ceramics hot-pressed at different temperatures

    Directory of Open Access Journals (Sweden)

    Carla Castiglia Gonzaga

    2008-09-01

    Full Text Available The objective of this work was to evaluate biaxial-flexural-strength (σf, Vickers hardness (HV, fracture toughness (K Ic, Young's modulus (E, Poisson's ratio (ν and porosity (P of two commercial glass-ceramics, Empress (E1 and Empress 2 (E2, as a function of the hot-pressing temperature. Ten disks were hot-pressed at 1065, 1070, 1075 and 1080 °C for E1; and at 910, 915, 920 and 925 °C for E2. The porosity was measured by an image analyzer software and s f was determined using the piston-on-three-balls method. K Ic and HV were determined by an indentation method. Elastic constants were determined by the pulse-echo method. For E1 samples treated at different temperatures, there were no statistical differences among the values of all evaluated properties. For E2 samples treated at different temperatures, there were no statistical differences among the values of σf, E, and ν, however HV and K Ic were significantly higher for 910 and 915 °C, respectively. Regarding P, the mean value obtained for E2 for 925 °C was significantly higher compared to other temperatures.

  15. Strength-ductility relationships in intermediate purity hot-pressed beryllium

    International Nuclear Information System (INIS)

    Stonehouse, A.J.; Bielawski, C.A.; Paine, R.M.

    1977-01-01

    The strength of vacuum hot-pressed, intermediate purity beryllium may be substantially increased without sacrifice of the strain capacity of the present grade (S-65) through decrease in the average grain size. Tensile strength of 517 MPa, 0.2% offset yield strength of 414 MPa with minimum 3% tensile elongation in all test directions could be commercially achieved. The tangent modulus of such material is quite attractive and suffers only about 10% degradation from room temperature to 260 0 C. The tangent modulus is dramatically enhanced by the presence of a yield point. The ductility of the materials studied did not appear to be affected by the BeO content across the range of 0.5 to 2.0% using nominal -44 to -15 μm powder particle sizes. All fine-grained pressings exhibited yield points in the as-pressed condition. Either full-density or sub-density hot-pressed billets given a hot isostatic pressing treatment without the use of cans showed only slight yield points after the HIP treatment with essentially the same strength and ductility factors as in the pressed condition. A plot of grain size vs yield strength in the as-pressed condition projects to an intercept with the fracture strength line at about 3 μm grain size. A similar plot after the HIP treatment shows a yield strength line parallel to the fracture strength line with no projected intercept predicting a completely brittle material. (author)

  16. Characteristics of hot-pressed fiber-reinforced ceramics with SiC matrix

    Science.gov (United States)

    Miyoshi, Tadahiko; Kodama, Hironori; Sakamoto, Hiroshi; Goto, Akihiro; Iijima, Shiroo

    1989-11-01

    Silicon carbide ceramics’ matrix composites with SiC or C filaments were fabricated through hot pressing, and the effects of the filament pullout on their fracture toughness were experimentally investigated. The C-rich coating layers on the SiC filaments were found to have a significant effect on the frictional stress at the filament/matrix interfaces, through assising the filamet pullout from the matrix. Although the coating layers were apt to burn out in the sintering process of SiC matrix compposites, a small addition of carbon to the raw materials was found to be effective for the retention of the layers on the fibers, thus increasing the fracture toughness of the composites. The fracture toughness of the C filament/SiC matrix composite increased with temperature due to the larger interfacial frictional stress at higher temperatures, because of the higher thermal expansion of the filament in the radial direction than that of the matrix.

  17. Interface characteristic during bonding of Be and HR-1 stainless steel by hot pressing

    International Nuclear Information System (INIS)

    Li Hui; Kang Renmu; Zhou Shangqi; Kong Jilan; Zhang Pengcheng

    2010-01-01

    Be and HR-I stainless steel was diffusion bonded by hot pressing. The microstructure,composition and phase distribution and mechanical properties of the joints were analyzed using the optical microscopy, scanning electron microscopy(SEM), scanning auger microspectroscopy(SAM) and x-ray diffraction(XRD), and the effect of different interlayer materials Cu and Al and Ag-Cu alloy was also discussed. The results show that it is not easy to joint Be and HR-1 stainless when Al was used as the interlayer material, but good joints can be obtained using Cu and Ag and Cu alloy as the interlayer materials, because the formation of Be-Fe brittle intermetallic compounds was prevented. Ag-Cu alloy is the best interlayer materials among them, as it can reduce the mutual diffusion between Be and Fe. (authors)

  18. TEM study of a hot-pressed Al2O3-NbC composite material

    Directory of Open Access Journals (Sweden)

    Wilson Acchar

    2005-03-01

    Full Text Available Alumina-based composites have been developed in order to improve the mechanical properties of the monolithic matrix and to replace the WC-Co material for cutting tool applications. Al2O3 reinforced with refractory carbides improves hardness, fracture toughness and wear resistance to values suitable for metalworking applications. Al2O3-NbC composites were uniaxially hot-pressed at 1650 °C in an inert atmosphere and their mechanical properties and microstructures were analyzed. Sintered density, average grain size, microhardness and fracture toughness measurements and microstructural features were evaluated. Results have shown that the mechanical properties of alumina-NbC are comparable to other carbide systems. Microstructural analysis has shown that the niobium carbide particles are mainly located at the grain boundaries of alumina grains, which is an evidence of the "pinning effect", produced by NbC particles.

  19. Effect of Liquid Phase Content on Thermal Conductivity of Hot-Pressed Silicon Carbide Ceramics

    International Nuclear Information System (INIS)

    Lim, Kwang-Young; Jang, Hun; Lee, Seung-Jae; Kim, Young-Wook

    2015-01-01

    Silicon carbide (SiC) is a promising material for Particle-Based Accident Tolerant (PBAT) fuel, fission, and fusion power applications due to its superior physical and thermal properties such as low specific mass, low neutron cross section, excellent radiation stability, low coefficient of thermal expansion, and high thermal conductivity. Thermal conductivity of PBAT fuel is one of very important factors for plant safety and energy efficiency of nuclear reactors. In the present work, the effect of Y 2 O 3 -Sc 2 O 3 content on the microstructure and thermal properties of the hot pressed SiC ceramics have been investigated. Suppressing the β to α phase transformation of SiC ceramics is beneficial in increasing the thermal conductivity of liquid-phase sintered SiC ceramics. Developed SiC ceramics with Y 2 O 3 -Sc 2 O 3 additives are very useful for thermal conductivity on matrix material of the PBAT fuel

  20. Phase transitions to 120 GPa for shock-compressed pyrolytic and hot-pressed boron nitride

    International Nuclear Information System (INIS)

    Gust, W.H.; Young, D.A.

    1977-01-01

    Shock-compression characteristics of two types of hexagonal graphitelike boron nitride have been investigated. Highly oriented very pure pyrolytic boron nitride exhibits shock-velocity versus particle-velocity discontinuities that appear to be manifestations of the initiation of a sluggish phase transition. This transition begins at 20 GPa and is driven to completion (melting) at 75 GPa. Discontinuities in the plot for impure hot-pressed boron nitride indicate initiation at 10 GPa and completion at 20 GPa. The (U/sub s/, U/sub p/) plots follow essentially the same paths for 4.0 < U/sub p/ < 5.2 km/sec. No evidence for a transition to a metalliclike state was seen. Temperature calculations indicate that the material is liquid above approx.80 GPa

  1. Transfer of microstructure pattern of CNTs onto flexible substrate using hot press technique for sensing applications

    International Nuclear Information System (INIS)

    Mishra, Prabhash; Tai, Nyan-Hwa; Harsh; Islam, S.S.

    2013-01-01

    Graphical abstract: - Highlights: • Successfully transfer of microstructure patterned CNTs on PET substrate. • Demonstrate as resistor-based NH 3 gas sensor in the sub-ppm range. • Excellent photodetector having instantaneous response and recovery characteristics. • An effective technique to grow and produce flexible electronic device. - Abstract: In this work, we report the successful and efficient transfer process of two- dimensional (2-D) vertically aligned carbon nanotubes (CNTs) onto polyethylene terephthalate (PET) substrate by hot pressing method with an aim to develop flexible sensor devices. Carbon nanotubes are synthesized by cold wall thermal chemical vapor deposition using patterned SiO 2 substrate under low pressure. The height of the pattern of CNTs is controlled by reaction time. The entire growth and transfer process is carried out within 30 min. Strong adhesion between the nanotube and polyethylene terephthalate substrate was observed in the post-transferred case. Raman spectroscopy and scanning electron microscope (SEM) studies are used to analyze the microstructure of carbon nanotube film before and after hot pressing. This technique shows great potential for the fabrication of flexible sensing devices. We report for the first time, the application of patterned microstructure developed by this technique in the development of gas sensor and optoelectronic device. Surface resistive mode is used for detection of ammonia (NH 3 ) gas in the sub-ppm range. An impressive photoconducting response is also observed in the visible wavelength. The reproducibility of the sample was checked and the results indicate the possibility of use of carbon nanotube as gas sensor, photodetector, CCDs etc

  2. Transfer of microstructure pattern of CNTs onto flexible substrate using hot press technique for sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Prabhash [Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Nano-Sensor Research Laboratory, F/O Engineering and Technology, Jamia Millia Islamia, Jamia Nagar, New Delhi (India); Tai, Nyan-Hwa [Department of Material Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Harsh [Nano-Sensor Research Laboratory, F/O Engineering and Technology, Jamia Millia Islamia, Jamia Nagar, New Delhi (India); Islam, S.S., E-mail: safiul5996@gmail.com [Nano-Sensor Research Laboratory, F/O Engineering and Technology, Jamia Millia Islamia, Jamia Nagar, New Delhi (India)

    2013-08-01

    Graphical abstract: - Highlights: • Successfully transfer of microstructure patterned CNTs on PET substrate. • Demonstrate as resistor-based NH{sub 3} gas sensor in the sub-ppm range. • Excellent photodetector having instantaneous response and recovery characteristics. • An effective technique to grow and produce flexible electronic device. - Abstract: In this work, we report the successful and efficient transfer process of two- dimensional (2-D) vertically aligned carbon nanotubes (CNTs) onto polyethylene terephthalate (PET) substrate by hot pressing method with an aim to develop flexible sensor devices. Carbon nanotubes are synthesized by cold wall thermal chemical vapor deposition using patterned SiO{sub 2} substrate under low pressure. The height of the pattern of CNTs is controlled by reaction time. The entire growth and transfer process is carried out within 30 min. Strong adhesion between the nanotube and polyethylene terephthalate substrate was observed in the post-transferred case. Raman spectroscopy and scanning electron microscope (SEM) studies are used to analyze the microstructure of carbon nanotube film before and after hot pressing. This technique shows great potential for the fabrication of flexible sensing devices. We report for the first time, the application of patterned microstructure developed by this technique in the development of gas sensor and optoelectronic device. Surface resistive mode is used for detection of ammonia (NH{sub 3}) gas in the sub-ppm range. An impressive photoconducting response is also observed in the visible wavelength. The reproducibility of the sample was checked and the results indicate the possibility of use of carbon nanotube as gas sensor, photodetector, CCDs etc.

  3. Investigation of microstructure in hot-pressed Nb–23Ti–15Al alloy

    International Nuclear Information System (INIS)

    Shi, Zhiwu; Wei, Hua; Zhang, Hongyu; Wu, Duoli; Jin, Tao; Sun, Xiaofeng; Zheng, Qi

    2015-01-01

    Highlights: • The Ti(O, C), a new strengthening phase, is found in Nb–Ti–Al alloys. • Ti(O, C) has a face-centered cubic structure and a lattice parameter of 4.27 Å. • Two different morphologies of Ti(O, C) are observed. • β and δ phases exhibit as large irregular blocks and equiaxed particles. • Ordering of β phase is observed in hot-pressed Nb–Ti–Al alloy. - Abstract: Microstructure of hot-pressed Nb–23Ti–15Al alloy has been systematically investigated, with emphasis on the characterization of Ti(O, C) phase. The microstructure and composition of Nb–23Ti–15Al alloy were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA). The results indicate the presence of β, δ and Ti(O, C) phases in the alloy. The β phase exhibits as large irregular blocks, while the δ phase presents as small equiaxed particles linked together around β blocks. Ordering of β phase is shown by related selected area electronic diffraction (SAED) patterns and dark-field micrograph. The Ti(O, C), a solid-solution of TiO or TiC, is characterized for the first time in Nb–Ti–Al alloy. The Ti(O, C) has a face-centered cubic (FCC) structure and a moderate lattice parameter between that of TiO and TiC. Two different morphologies of Ti(O, C) are observed in the alloy: large cobblestone-like aggregated particles and small dispersive particles. The formation of Ti(O, C) phase can potentially increase high-temperature strength of Nb–Ti–Al alloy

  4. Investigation of microstructure in hot-pressed Nb–23Ti–15Al alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhiwu; Wei, Hua; Zhang, Hongyu; Wu, Duoli; Jin, Tao; Sun, Xiaofeng; Zheng, Qi, E-mail: qzheng@imr.ac.cn

    2015-07-05

    Highlights: • The Ti(O, C), a new strengthening phase, is found in Nb–Ti–Al alloys. • Ti(O, C) has a face-centered cubic structure and a lattice parameter of 4.27 Å. • Two different morphologies of Ti(O, C) are observed. • β and δ phases exhibit as large irregular blocks and equiaxed particles. • Ordering of β phase is observed in hot-pressed Nb–Ti–Al alloy. - Abstract: Microstructure of hot-pressed Nb–23Ti–15Al alloy has been systematically investigated, with emphasis on the characterization of Ti(O, C) phase. The microstructure and composition of Nb–23Ti–15Al alloy were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA). The results indicate the presence of β, δ and Ti(O, C) phases in the alloy. The β phase exhibits as large irregular blocks, while the δ phase presents as small equiaxed particles linked together around β blocks. Ordering of β phase is shown by related selected area electronic diffraction (SAED) patterns and dark-field micrograph. The Ti(O, C), a solid-solution of TiO or TiC, is characterized for the first time in Nb–Ti–Al alloy. The Ti(O, C) has a face-centered cubic (FCC) structure and a moderate lattice parameter between that of TiO and TiC. Two different morphologies of Ti(O, C) are observed in the alloy: large cobblestone-like aggregated particles and small dispersive particles. The formation of Ti(O, C) phase can potentially increase high-temperature strength of Nb–Ti–Al alloy.

  5. Nanostructured Al–Zn–Mg–Cu–Zr alloy prepared by mechanical alloying followed by hot pressing

    International Nuclear Information System (INIS)

    Azimi, Amin; Shokuhfar, Ali; Zolriasatein, Ashkan

    2014-01-01

    Nanostructured Al–7.8 wt% Zn–2.6 wt% Mg–2 wt% Cu–0.1 wt% Zr alloy was mechanically alloyed (MA) from elemental powders and consolidated by hot press technique. The effect of the milling time and hot pressing process on microstructure was investigated by means of X-ray diffraction measurements (XRD) and analytical and scanning electron microscopy (SEM). Furthermore mechanical properties of samples with different MA time as well as pure aluminum were investigated by microhardness and compression tests. The results show that an Al–Zn–Mg–Cu–Zr homogenous supersaturated solid solution with a crystallite size of 27 nm was obtained after 40 h of milling time. Microstructure refinement and morphological changes of powders from flake to spherical shape were observed by increasing milling time. Phase and microstructural characterization of high density bulk nanostructured samples revealed that increasing milling time up to 40 h leads to formation of MgZn 2 precipitation in the alloy matrix. With increasing milling time, density of the samples and crystalline size decrease. Significant enhancement of hardness and compressive strength is observed in the aluminum alloy by increasing milling time up to 40 h which is much higher than pure aluminum. Crystallite size refinement in pure aluminum samples from micro- to nanoscales resulted in 107% and 100% improvement in compressive strength and hardness, respectively. Furthermore the compressive strength and hardness of Al–Zn–Mg–Cu–Zr alloy nanostructured samples increased to 179% and 172%, respectively, compared to nanostructured pure Al, which was produced as reference specimen. 40 h of MA was the optimum case for preparing such an Al alloy and more milling up to 50 h led to deterioration of mechanical properties

  6. The influence of process parameters and additives on the densification, creep properties and strength of hot pressed silicon nitride

    International Nuclear Information System (INIS)

    Becker, R.

    1979-03-01

    One method of production of Si 3 N 4 parts is the hot pressing of powder compacts. According to the current technological know how, a liquid phase building additive (e.g. MgO) is essential for the complete densification of Si 3 N 4 . In this work it has been shown, how dense Si 3 N 4 may be produced without the conventional additives. The SiO 2 -coating of Si 3 N 4 particles here results in the liquid phase formation. On the basis of the above concept, the effect of MgO, Mg 3 N 2 , Al 2 O 3 and A1N-additions to a pure Si 3 N 4 powder have been studied in detail and the resulting material properties: densification, creep and high temperature strengths have been determined. Based on the results, it may be concluded, that HPSN is a dispersion of crystalline Si 3 N 4 in an amorphous matrix (glass content between 4-10 vol%). Depending on the amount and composition of the boundary phase (silicate glass) widely variing material properties may be obtained. (orig./GSCH) [de

  7. Coercivity enhancement of HDDR-processed Nd-Fe-B permanent magnet with the rapid hot-press consolidation process

    Energy Technology Data Exchange (ETDEWEB)

    Nozawa, N. [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., Osaka 618-0013 (Japan); Sepehri-Amin, H. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Magnetic Materials Center, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Ohkubo, T. [Magnetic Materials Center, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Hono, K. [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Magnetic Materials Center, National Institute for Materials Science, Tsukuba 305-0047 (Japan); Nishiuchi, T. [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., Osaka 618-0013 (Japan); Hirosawa, S., E-mail: Satoshi_Hirosawa@hitachi-metals.co.j [Magnetic Materials Research Laboratory, NEOMAX Company, Hitachi Metals Ltd., Osaka 618-0013 (Japan)

    2011-01-15

    High coercivity, fully dense anisotropic permanent magnets of submicron grain sizes were produced by rapid hot-press consolidation of hydrogenation-disproportionation-desorption-recombination (HDDR) processed Nd-Fe-Co-B powders. In the hot-press process, the coercivity of the consolidated material showed a sharp minimum prior to full densification. Thereafter, it reached a value 25% higher than that of the initial powder. Scanning electron microscopy and transmission electron microscopy observations revealed that the variation in H{sub cJ} was caused by a redistribution of Nd along the grain boundaries during hot pressing and that the high coercivity was attributable to the formation of thin, continuous Nd-rich phase along the grain boundaries.

  8. Ceramic nuclear waste forms. II. A ceramic-waste composite prepared by hot pressing. Progress report and preprint

    International Nuclear Information System (INIS)

    McCarthy, G.J.

    1975-01-01

    A feasibility study was conducted to determine whether nuclear waste calcine and a crystalline ceramic matrix can be fabricated by hot pressing into a composite waste form with suitable leaching resistance and thermal stability. It was found that a hard, dense composite could be formed using the typical commercial waste formulation PW-4b and a matrix of α-quartz with a small amount of a lead borosilicate glass added as a consolidation aide. Its density, waste loading, and leaching resistance are comparable to the glasses currently being considered for fixation of nuclear wastes. The hot pressed composite offers a closer approach to thermodynamic stability and improved thermal stability (in monolithic form) compared to glass waste forms. Recommendations for further optimization of the hot pressed waste form are given. (U.S.)

  9. Process controls for Bi2Te3-Sb2Te3 prepared by mechanical alloying and hot pressing

    International Nuclear Information System (INIS)

    Lee, Go-Eun; Kim, Il-Ho; Choi, Soon-Mok; Lim, Young-Soo; Seo, Won-Seon; Park, Jae-Soung; Yang, Seung-Ho

    2014-01-01

    p-Type Bi 2 Te 3 -Sb 2 Te 3 solid solutions were prepared by mechanical alloying (MA) and hot pressing (HP) under different process conditions, after which the transport and the thermoelectric properties were evaluated. The relative densities of all hot-pressed specimens were over 98%, and the microstructure and crystal orientation were independent of the HP direction. All specimens exhibited p-type conduction, and the electrical resistivity was observed to increase slightly with increasing temperature, indicating a degenerate semiconductor behavior. The carrier concentration decreased with increasing HP temperature while the mobility increased. The maximum figure of merit obtained was 0.86 at 323 K for Bi 0.5 Sb 1.5 Te 3 hot-pressed at 648 K.

  10. Microstructure and thermoelectric properties of β-FeSi2 ceramics fabricated by hot-pressing and spark plasma sintering

    International Nuclear Information System (INIS)

    Qu Xiurong; Lue Shuchen; Hu Jianmin; Meng Qingyu

    2011-01-01

    Highlights: → With increasing hot-pressing (HP) temperature, the thermoelectric figure of merit of β-FeSi 2 ceramics is improved slightly. → The grain size of the sample sintered by the spark plasma sintering (SPS) process is smaller than that by the HP process. → The SPS sample shows excellent thermoelectric performance attributed to low thermal conductivity. - Abstract: The microstructure and thermoelectric properties of β-FeSi 2 ceramics by hot pressing (HP) and spark plasma sintering (SPS) are investigated. With increasing hot-pressing temperature, the density, electronic conductivity and thermal conductivity of the samples increase significantly, the thermoelectric figure of merit is improved slightly. The microstructure study indicates that the sizes of the β-FeSi 2 and ε-FeSi phases in the sample sintered by the SPS process are smaller than that by the HP process. The SPS sample shows excellent thermoelectric performance due to the low thermal conductivity.

  11. Mechanical and thermal expansion properties of β-eucryptite prepared by sol-gel methods and hot pressing

    International Nuclear Information System (INIS)

    Xia, L.; Wen, G.W.; Qin, C.L.; Wang, X.Y.; Song, L.

    2011-01-01

    Research highlights: → Dense LAS glass-ceramics were fabricated by sol-gel and hot pressing technique. → The LAS glass-ceramics have relative good mechanical properties. → The negative thermal expansion behavior of LAS glass-ceramics was investigated. -- Abstract: The microstructures, mechanical properties and thermal expansion behavior of monolithic lithium aluminosilicate glass-ceramics, prepared by sol-gel method and hot pressing, were investigated by using X-ray diffraction, scanning and transmission electron microscopies, three-point bend tests and dilatometry. β-eucryptite appeared as main phase in the monolithic lithium aluminosilicate glass-ceramics. The glass ceramics exhibited high relative densities and the average flexural strength and fracture toughness values were 154 MPa and 2.46 MPa m 1/2 , respectively. The lithium aluminosilicate glass-ceramics hot pressed 1300 and 1350 o C demonstrated negative coefficient of thermal expansion, which was affected by amount and type of crystalline phases.

  12. Effect of phosphorus additions on hot pressing temperature and some properties of WC-Co hard alloys

    International Nuclear Information System (INIS)

    Dotsenko, V.M.; Simkina, Eh.S.; Tsypin, N.V.

    1977-01-01

    Results of studies on the effect of phosphorus additions on hot pressing temperature and some properties of VK6 and VK15 hard alloys are given. It is shown that alloying of hard alloys with 3-6 wt % phosphorus gives opportunity to lower substantially (for 200-300 deg) their hot pressing temperature. Hardness and density of alloys with phosphorus do not practically change. Some decrease of strength and wear-resistance characteristics is observed which is obviously connected with irregular distribution of phosphorus in the alloy

  13. Wettability of hot-pressed samples of boron-containing aluminium compounds by liquid metals and alloys

    International Nuclear Information System (INIS)

    Kharlamov, A.I.; Nizhenko, V.I.; Kirillova, N.V.; Floka, L.I.

    2000-01-01

    Highly dispersed powders of aluminium borides and borocarbides were sintered by hot pressing method. Temperature dependence of wettability of hot-pressed boride samples (α-AlB 12 and AlB 18 ) and aluminium borocarbides (Al 3 B 48 C 2 , Al 8 B 4 C 2 and AlB 24 C) by liquid aluminium, copper, germanium, silicon and melts Al + 25 wt.%Si and Cu + (3-6) wt.%Ti was studied. Dependence of a compound wettability on the ratio of components in it was analyzed [ru

  14. The Novel Design and Manufacturing Technology of Densified RDF from Reclaimed Landfill without a Mixing Binding Agent Using a Hydraulic Hot Pressing Machine

    Directory of Open Access Journals (Sweden)

    Kerdsuwan Somrat

    2016-01-01

    Full Text Available The manufacturing of RDF (Refuse Derived Fuel from a conventional cold press extrusion machine is not suitable for producing RDF from reclaimed landfill since it is not identical in shape and form after production due to the swelling of the plastic fraction contained inside the reclaimed landfill and hence needs a very high compression force. Moreover, a binder agent is needed in order to keep the RDF in a similar shape and form. A novel design and manufacturing technology for a hydraulic hot pressing machine has been established and can produce high-quality RDF without any binder. The two electrical heaters are installed at the inner core and on the surface of the mold. The compression force on the mold is performed by a hydraulic jack. In addition, a newly-designed locking plate system which is designed by a slider to open and close along the paired horizontal slots, can reduce the cycle time of the manufacturing process and yield higher productivity. The testing properties of the RDF produced by the novel hydraulic hot pressing machine include the examination of size, shape, weight, unit density, bulk density, compression strength, moisture content, and heating value. The results showed that the RDF is suitable to be used as feedstock in an incinerator or gasifier to produce green and clean energy from reclaimed landfill.

  15. Hot pressing effect on (Bi 0.25 Sb 0.75 ) 2 Te 3 mechanical and ...

    Indian Academy of Sciences (India)

    Hot pressing effect on (Bi0.25Sb0.75)2Te3 mechanical and thermoelectric properties ... The crystal of this compound was prepared, pulverized in a particle size ratio of 64% ... microscopy and, for only once successful attempt, atomic force microscopy. The acquired images ensured to show homogeneous structures for hot ...

  16. Microstructure of in-situ Synthesized (TiB+TiC)/Ti Composites Prepared by Hot-pressing

    Institute of Scientific and Technical Information of China (English)

    Zhenzhu ZHENG; Lin GENG; Honglin WANG; Weimin ZHOU; Hongyu XU

    2003-01-01

    In-situ 5 vol.pct TiB whiskers and TiC particulates reinforced Ti composites were fabricated by blending Ti powderand B4C particulates followed by reactive hot-pressing. The microstructure of the composites was investigated byusing differential scanning c

  17. Effect of Furnish on Temperature and Vapor Pressure Behavior in the Center of Mat Panels during Hot Pressing

    Directory of Open Access Journals (Sweden)

    Muhammad Navis Rofii

    2014-07-01

    Full Text Available Particleboard achieves its overall performance characteristics during hot pressing process. As this process is influenced by several factors, particularly temperature and pressure, it is very important to understand the behavior of both. This study investigates the effects of furnish materials on temperature and vapor pressure behavior inside particleboard mat panels during hot pressing. Strand type particles from hinoki and ring-flaker recycled wood particles were used as furnish for laboratory-scale particleboard panels with a target density of 0.76 g/cm³. Mat panels with a moisture content of about 10% were hot pressed at a platen temperature of 180°C and an initial pressure of 3 MPa until the mat center reached the same temperature as the platen. A press monitoring device (PressMAN Lite was used for detecting the temperature and vapor pressure change in the center of the mat panels. The study showed that the furnish type affected the temperature and vapor behavior inside the mat panels. Particleboard made of hinoki strand resulted in a longer plateau time, a higher plateau temperature and a higher gas pressure generated during hot pressing than those of ring-flaker recycled wood particles. Mixed board resulted in values between those of the two other furnish materials.

  18. Mechanical properties of hot-pressed SiC-TiC composites

    Directory of Open Access Journals (Sweden)

    Kamil Kornaus

    2017-12-01

    Full Text Available SiC-TiC composites, with 0, 5, 10 and 20 vol.% of TiC, were sintered by the hot-pressing technique at temperature of 2000 °C under argon atmosphere. SiC sintering process was activated by liquid phase created by the reaction between Al2O3 and Y2O3, in which it is possible to dissolve passivating oxide layers (SiO2 and TiO2 and partially SiC and TiC carbides. Microstructure observation and density measurements confirmed that the composites were dense with uniformly distributed components. Differences in thermal expansion coefficients between SiC and TiC led to complex stress state occurrence. These stresses combined with the liquid-derived separate phase between grains boundaries increased fracture toughness of the composites, which ranged from 5.8 to 6.3 MPa·m0.5. Opposite to the bending strength, fracture toughness increased with the TiC volume fraction. By means of simulation of residual thermal stresses in the composites, it was found that with the increasing volume fraction of TiC, tensile stress in TiC grains is reduced simultaneously with strong rise of compressive stresses in the matrix.

  19. Fabrication of SiCp/Al Alloy Composites by In-situ Vacuum Hot Press Process

    Energy Technology Data Exchange (ETDEWEB)

    Choi, S. W.; Hong, S. K.; Kim, Y. M.; Kang, C. S. [Chonnam National University, Kwangju (Korea); Chang, S. Y. [Hanyang University, Seoul (Korea)

    2001-07-01

    SiCp/pure Al and SiCp/2024Al MMCs were fabricated by in-situ VHP process designed specially just in this study which is composed of the vacuum hot press at range from R.T. to 500 deg.C and the continuous extrusion without canning process at 520 deg.C. It was investigated the effect of SiC particle size, volume fraction and extrusion ratio on the tensile properties and micro structure in all composites. In case of the 10:1 extrusion ratio, but SiCp/pure Al and SiCp/2024Al composites were shown a sound appearance and a good micro structure without crack of SiCp as well as uniform distribution of SiCp. However, in case of the 16:1 extrusion ratio, the number of cracked SiC particles more than increased in a higher volume fraction composite and 2024Al matrix composite compared with pure Al matrix one. The tensile strength of the composites reinforced smaller SiCp was higher than that of the bigger SiCp reinforced in same volume fraction and extrusion ratio. (author) 14 refs., 14 figs.

  20. Dynamic Failure and Fragmentation of a Hot-Pressed Boron Carbide

    Science.gov (United States)

    Sano, Tomoko; Vargas-Gonzalez, Lionel; LaSalvia, Jerry; Hogan, James David

    2017-12-01

    This study investigates the failure and fragmentation of a hot-pressed boron carbide during high rate impact experiments. Four impact experiments are performed using a composite-backed target configuration at similar velocities, where two of the impact experiments resulted in complete target penetration and two resulted in partial penetration. This paper seeks to evaluate and understand the dynamic behavior of the ceramic that led to either the complete or partial penetration cases, focusing on: (1) surface and internal failure features of fragments using optical, scanning electron, and transmission electron microscopy, and (2) fragment size analysis using state-of-the-art particle-sizing technology that informs about the consequences of failure. Detailed characterization of the mechanical properties and the microstructure is also performed. Results indicate that transgranular fracture was the primary mode of failure in this boron carbide material, and no stress-induced amorphization features were observed. Analysis of the fragment sizes for the partial and completely penetrated experiments revealed a possible correlation between larger fragment sizes and impact performance. The results will add insight into designing improved advanced ceramics for impact protection applications.

  1. Characterization and Formability of Titanium/Aluminum Laminate Composites Fabricated by Hot Pressing

    Science.gov (United States)

    Qin, Liang; Wang, Hui; Cui, Shengqiang; Wu, Qian; Fan, Minyu; Yang, Zonghui; Tao, Jie

    2017-07-01

    The Ti/Al laminate composites were prepared by hot pressing to investigate the forming performance due to the corresponding potential applications in both the aerospace and auto industry. The bonding interface morphology and element distributions were characterized by SEM and EDS. The phase constituent was detected by XRD. It was observed that these composites presented good bonding interfaces between Ti and Al layers, and no low-sized voids and intermetallic compounds formed at the interface. In addition, the formability of these laminate composites was studied by the uniaxial tension tests, the limit drawing ratio (LDR) and the forming limit curve (FLC) experiments, respectively. The results indicated that the flow stress increased along with the strain rate increment. A constitutive equation was developed for deformation behavioral description of these laminate composites. The LDR value was 1.8, and the most susceptible region to present cracks was located at the punch profile radius. The forming limit curve of the laminate composites was located between the curves of titanium and aluminum and intersected with the major strain line at approximately 0.31. The macroscopic cracks of the FLC sample demonstrated a saw-toothed crack feature.

  2. Effect of roll hot press temperature on crystallite size of PVDF film

    Energy Technology Data Exchange (ETDEWEB)

    Hartono, Ambran, E-mail: ambranhartono@yahoo.com; Sanjaya, Edi [Departement of Physics Faculty of Science and Technology, Islamic State University Syarif Hidayatullah , Jl. Juanda 95 Ciputat Jakarta (Indonesia); Djamal, Mitra; Satira, Suparno; Bahar, Herman [Theoretical High Energy Physics and Instrumentation Group Research, Faculty Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung (Indonesia); Ramli [Departement of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Padang, Jl.Prof. Hamka, Padang 25131 (Indonesia)

    2014-03-24

    Fabrication PVDF films have been made using Hot Roll Press. Preparation of samples carried out for nine different temperatures. This condition is carried out to see the effect of Roll Hot Press temperature on the size of the crystallite of PVDF films. To obtain the diffraction pattern of sample characterization is performed using X-Ray Diffraction. Furthermore, from the diffraction pattern is obtained, the calculation to determine the crystallite size of the sample by using the Scherrer equation. From the experimental results and the calculation of crystallite sizes obtained for the samples with temperature 130 °C up to 170 °C respectively increased from 7.2 nm up to 20.54 nm. These results show that increasing temperatures will also increase the size of the crystallite of the sample. This happens because with the increasing temperature causes the higher the degree of crystallization of PVDF film sample is formed, so that the crystallite size also increases. This condition indicates that the specific volume or size of the crystals depends on the magnitude of the temperature as it has been studied by Nakagawa.

  3. Hot-pressed silicon nitride with various lanthanide oxides as sintering additives

    Science.gov (United States)

    Ueno, K.; Toibana, Y.

    1984-01-01

    The effects of addition of various lanthanide oxides and their mixture with Y2O3 on the sintering of Si3N4 were investigated. The addition of simple and mixed lanthanide oxides promoted the densification of Si3N4 in hot-pressing at 1800 C under 300-400kg/ centimeters squared for 60 min. The crystallization of yttrium and lanthanide-silicon oxynitrides which was observed inn the sintered body containing yttrium-lanthanide mixed oxides as additives led to the formation of a highly refractory Si3N4 ceramic having a bending strength of 82 and 84 kg/millimeters squared at room temperature and 1300 C respectively. In a Y2O3+La2O3 system, a higher molar ratio of La2O3 to Y2O3 gave a higher hardness and strength at high temperatures. It was found that 90 min was an optimum sintering time for the highest strength.

  4. Densification of boron carbide at relatively low temperatures by hot pressing and hot isostatic pressing

    International Nuclear Information System (INIS)

    Telle, R.

    1988-01-01

    The poor sinterability of B 4 C limits its widespread application because both high temperatures and high pressures are required for a complete densification. Moreover, B 4 C suffers from a low strength and fracture toughness, possesses, however, a high potential because of its extreme hardness. Reaction hot pressing of B 4 C-WC-TiC-Si-Co mixtures resulting in B 4 C-TiB 2 -W 2 B 5 composites of high density exhibit remarkable mechanical properties. The influence of hot isostatic pressing (HIP) on the microstructure and the mechanical properties is investigated in cooperation with participants of the COST 503 activities and related to the strengthening and toughening mechanisms. Difficulties during densification by HIP arise from the evaporation of adsorbed volatiles as well as from the strong swelling of the powder compact due to the sintering reaction. Several HIP cycle designs were tested in order to prevent the bloating of the capsule and to control internal stresses due to the misfit of the thermal expansion of the entire phases. In comparison to single phase B 4 C ceramics, bending strength was improved to 1030 MPa, K Ic to 5.2 MPa/m, while hardness was comparable with HV1=38 GPa. Wear test were performed and related to the toughening mechanisms. (orig.) With 56 refs., 9 tabs., 64 figs

  5. Life-Cycle Inventory Analysis of Laminated Veneer Lumber Production in the United States

    Science.gov (United States)

    Richard D. Bergman

    2015-01-01

    Documenting the environmental performance of building products is becoming increasingly common. Developing environmental product declarations (EPDs) based on life-cycle assessment (LCA) data is one way to provide scientific documentation. Many U.S. structural wood products have LCA-based “eco-labels” using the ISO standard. However, the standard requires underlying...

  6. Effect of rapid solidification on the microstructure and mechanical properties of hot-pressed Al-20Si-5Fe alloys

    International Nuclear Information System (INIS)

    Rajabi, M.; Vahidi, M.; Simchi, A.; Davami, P.

    2009-01-01

    The aim of this work is to study the effect of cooling rate and subsequent hot consolidation on the microstructural features and mechanical strength of Al-20Si-5Fe-2X (X = Cu, Ni and Cr) alloys. Powder and ribbons were produced by gas atomization and melt spinning processes at two different cooling rates of 1 x 10 5 K/s and 5 x 10 7 K/s. The microstructure of the products was examined using optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The particles were consolidated by hot pressing at 400 deg. C/250 MPa/1 h under a high purity argon atmosphere and the microstructure, hardness and compressive strength of the compacts were evaluated. Results showed a profound effect of the cooling rate, consolidation stage, and transition metals on the microstructure and mechanical strength of Al-20Si-5Fe alloys. While microstructural refining was obtained at both cooling rates, the microstructure of the atomized powder exhibited the formation of fine primary silicon (∼ 1 μm), eutectic Al-Si phase with eutectic spacing of ∼ 300 nm, and δ-iron intermetallic. Supersaturated Al matrix containing 5-7 at.% silicon and nanometric Si precipitates (20-40 nm) were determined in the microstructure of the melt-spun ribbons. The hot consolidation resulted in coarsening of Si particles in the atomized particles, and precipitation of Si and Fe-containing intermetallics from the supersaturated Al matrix in the ribbons. The consolidated ribbons exhibited higher mechanical strength compared to the atomized powders, particularly at elevated temperatures. The positive influence of the transition metals on the thermal stability of the Al-20Si-5Fe alloy was noticed, particularly in the Ni-containing alloy.

  7. Veneer industry and timber use, North Central Region, 1980.

    Science.gov (United States)

    James E. Blyth; W. Brad Smith

    1984-01-01

    Shows 1980 veneer-log production and receipts by species in the Lake State (Michigan, Minnesota, and Wisconsin) and in the Central States (Illinois, Indiana, Iowa, and Missouri). Comparisons are made with similar data collected in 1976. Includes tables showing veneer-log production and receipts (for selected years) since 1946 in the Lake States and since 1956 in the...

  8. The Investigation on Feasibility of Oriented Strand Boards to Parquet Production from Mixed Residual Veneer Popular and Beech

    Directory of Open Access Journals (Sweden)

    Saeid Kamrani

    2013-06-01

    Full Text Available The objective of this study was to investigate of feasibility of using residual veneer (popular and beechto manufacture oriented strand board (OSB parquet. Percentage of mixed residual veneer popular to beech was 40%to 60% respectly. In this study press time (6, 8 and 10 min and press temperature (170º, 180ºwere selected as variables, other factors being kept constant. Results indicated that increase of press temperature had no significant effect on modules of rupture, modules of elasticity and hardness but had significant effect on internal bonding, water absorption and thickness swelling. However results indicated that increase of press time had significant effect on total physical and mechanical properties of boards.

  9. The influence of powder composition and sintering temperature on transformation kinetics, structure and mechanical properties of hot-pressed silicon nitride

    International Nuclear Information System (INIS)

    Knoch, H.; Ziegler, G.

    1977-01-01

    The strength at room temperature of hot-pressed silicon nitride is strongly dependent on the structure which in turn depends on powder composition and process parameters. Connections between production conditions (MgO content, pressing temperature, pressing time), structure (α/β content and morphology), and the properties at room temperature are discussed. The growth of oblong β grains - as a direct result of phase transition from α- to β-Si 3 N 4 - results in microstructural meshing and thus in a higher strength. Optimum mechanical properties are achieved after full phase transformation and with a microstructure as fine as possible. The direct connection between strength and transformed β fraction indicates a possible way for a relatively fast determination of optimum properties for a given initial powder. (orig.) [de

  10. The effect of hot pressing time on the microstructure and properties of Laves phase NbCr{sub 2} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, X. [College of Electromechanical Engineering, Nanjing University of Aeronautical and Astronautics, Nanjing 210016 (China); School of Materials Science and Engineering, Nanchang Institute of Aeronautical Technology, Nanchang 330063 (China); Lu, S.Q. [School of Materials Science and Engineering, Nanchang Institute of Aeronautical Technology, Nanchang 330063 (China)], E-mail: niatlusq@126.com; Hu, P.; Huang, M.G.; Nie, X.W. [School of Materials Science and Engineering, Nanchang Institute of Aeronautical Technology, Nanchang 330063 (China); Fu, M.W. [Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2008-06-25

    The microstructure and properties were investigated on the Laves phase NbCr{sub 2} alloys prepared through 20 h mechanical alloying of niobium and chromium powders and subsequent hot pressing at 1250 deg. C for different time. The results indicate that the Laves phase NbCr{sub 2} alloy with homogeneous microstructure and fine grains and high relative density is obtained. With the increase of hot pressing time, the density, grain size and Vickers hardness increase, the fracture toughness, however, decreases gradually. The alloy fabricated by hot pressing at 1250 deg. C for 30 min has the best overall properties. Its average grain size reaches about 248 nm, the relative density is 97.8% and the fracture toughness at room temperature is more than 4.7 MPa m{sup 1/2}. Compared with the Laves phase NbCr{sub 2} alloy prepared by arc-melting, which has the fracture toughness of 1.2 MPa m{sup 1/2}, the fracture toughness in this research is increased significantly.

  11. Preparation of 50Ni-45Ti-5Zr powders by high-energy ball milling and hot pressing

    Energy Technology Data Exchange (ETDEWEB)

    Marinzeck de Alcantara Abdala, Julia, E-mail: juabdala@yahoo.com.b [Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Av. Shishima Hifumi, 2911, 12244-000 Sao Jose dos Campos (Brazil); Bacci Fernandes, Bruno, E-mail: brunobacci@yahoo.com.b [Divisao de Engenharia Mecanica, Instituto Tecnologico de Aeronautica, Praca Marechal-do-Ar Eduardo Gomes, 50, 12228-904 Sao Jose dos Campos (Brazil); Santos, Dalcy Roberto dos, E-mail: dalcy@iae.cta.b [Instituto de Aeronautica e Espaco, Centro Tecnologico Aeroespacial, Praca Marechal-do-Ar Eduardo Gomes, 50, 12228-904 Sao Jose dos Campos (Brazil); Rodrigues Henriques, Vinicius Andre, E-mail: vinicius@iae.cta.b [Instituto de Aeronautica e Espaco, Centro Tecnologico Aeroespacial, Praca Marechal-do-Ar Eduardo Gomes, 50, 12228-904 Sao Jose dos Campos (Brazil); Moura Neto, Carlos de, E-mail: mneto@ita.b [Divisao de Engenharia Mecanica, Instituto Tecnologico de Aeronautica, Praca Marechal-do-Ar Eduardo Gomes, 50, 12228-904 Sao Jose dos Campos (Brazil); Saraiva Ramos, Alfeu, E-mail: alfeu@univap.b [Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraiba, Av. Shishima Hifumi, 2911, 12244-000 Sao Jose dos Campos (Brazil)

    2010-04-16

    This study reports on the preparation of the 50Ni-45Ti-5Zr (at.%) alloy by high-energy ball milling and hot pressing. The elemental powder mixture was processed in silicon nitride and hardened steel vials, and samples were collected after different milling times. To recover the previous powders in addition wet milling isopropyl alcohol (for 20 min) was adopted. The mechanically alloyed powders were hot-pressed under vacuum at 900 {sup o}C for 1 h using pressure levels close to 200 MPa. The milled powders were characterized by means of scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry techniques. It was noted that the ductile starting powders were continuously cold-welded during ball milling. This fact was more pronounced during the processing of 50Ni-45Ti-5Zr powders in hardened steel vial. After milling for 5 h, the results suggested that amorphous and nanocrystalline structures were achieved. The complete consolidation was found after hot pressing of mechanically alloyed 50Ni-45Ti-5Zr powders, and a large amount of the B2-NiTi phase was formed mainly after processing in stainless steel balls and vial.

  12. Microstructure and mechanical properties of Ti–22Al–25Nb alloy fabricated by vacuum hot pressing sintering

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Jianbo, E-mail: jiajianbohit@163.com [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); School of Mechanical Engineering, Beihua University, Jilin 132021 (China); Zhang, Kaifeng; Jiang, Shaosong [National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

    2014-10-20

    A study has been undertaken to verify the feasibility of using a powder metallurgy (P/M) approach to fabricate Ti–22Al–25Nb alloys. Pre-alloyed powders with a nominal composition of Ti–22Al–25Nb (at%) obtained by argon atomization were sieved to the spherical size less than 180 μm and used for the fabrication of P/M Ti–22Al–25Nb alloys via hot pressing in vacuum. Vacuum hot pressing sintering was carried out in a temperature range of 950–1200 °C with a pressure of 35 MPa for 1 h followed by furnace cooling. Microstructure and phase composition examinations of the as-atomized powders and hot pressed (HP'ed) samples were conducted by applying optical microscopy, back-scatter electron imaging and X-ray diffraction analysis. Tensile tests were studied at room temperature and 650 °C, respectively. The results showed that all HP'ed samples were composed of coarse equiaxed B2 grains, fine lamellar O phase inside the B2 grains, and some α{sub 2} along B2 grain boundaries. The elongations of HP'ed samples were less than 3.95%, indicating the bad ductility at room temperature. However, the elongations were improved as the tensile temperature increased to 650 °C. The sample sintered at 1050 °C exhibited a better ductility with the elongation of 7.97% at 650 °C than that of other samples.

  13. Effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics.

    Science.gov (United States)

    Hooshmand, Tabassom; Parvizi, Shaghayegh; Keshvad, Alireza

    2008-07-01

    The purpose of this study was to assess the effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics reinforced by leucite or lithium disilicate crystals. Forty glass ceramic disks (14-mm diameter, 2-mm thick) consisting of 20 leucite-based ceramic disks (IPS Empress) and 20 lithia disilicate-based ceramic (IPS Empress 2) were produced by hot-pressing technique. All specimens were polished and then cleaned ultrasonically in distilled water. Ten specimens of each ceramic group were then etched with 9% hydrofluoric (HF) acid gel for 2 minutes and cleaned ultrasonically again. The biaxial flexural strength was measured by the piston-on-three-ball test in a universal testing machine. Data based on ten specimens in each group were analyzed by two-way ANOVA (alpha= 0.05). Microstructure of ceramic surfaces before and after acid etching was also examined by a scanning electron microscope. The mean biaxial flexural strength values for each group tested were (in MPa): nonetched IPS Empress = 118.6 +/- 25.5; etched IPS Empress = 102.9 +/- 15.4; nonetched IPS Empress 2 = 283.0 +/- 48.5; and etched IPS Empress 2 = 250.6 +/- 34.6. The results showed that the etching process reduced the biaxial flexural strengths significantly for both ceramic types (p= 0.025). No significant interaction between the ceramic type and etching process was found (p= 0.407). From the results, it was concluded that surface HF acid etching could have a weakening effect on hot-pressed leucite or lithia disilicate-based glass ceramic systems.

  14. Importance of Electrode Hot-Pressing Conditions for the Catalyst Performance of Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Dhiman, Rajnish; Larsen, Mikkel Juul

    2015-01-01

    The catalyst performance in a proton exchange membrane fuel cell (PEMFC) depends on not only the choice of materials, but also on the electrode structure and in particular on the interface between the components. In this work, we demonstrate that the hot-pressing conditions used during electrode...... lamination have a great influence on the catalyst properties of a low-temperature PEMFC, especially on its durability. Lamination pressure, temperature and duration were systematically studied in relation to the electrochemical surface area, platinum dissolution, platinum particle size and electrode surface...

  15. Thermoelectric properties of Bi2Te3-Bi2Se3 solid solutions prepared by attrition milling and hot pressing

    International Nuclear Information System (INIS)

    Lee, Go-Eun; Kim, Il-Ho; Choi, Soon-Mok; Lim, Young-Soo; Seo, Won-Seon; Park, Jae-Soung; Yang, Seung-Ho

    2014-01-01

    Bi 2 Te 3-y Se y (y = 0.15 - 0.6) solid solutions were prepared by attrition milling and hot pressing. The lattice constants decreased with increasing Se content, indicating that the Se atoms were successfully substituted into the Te sites. All specimens exhibited n-type conduction, and their electrical resistivities increased slightly with increasing temperature. With increasing Se content, the Seebeck coefficients increased while the thermal conductivity decreased due to the increase in phonon scattering. The maximum figure of merit obtained was 0.63 at 440 K for the undoped Bi 2 Te 2.4 Se 0.6 solid solution.

  16. Biodegradable Poly(Lactic Acid/Multiwalled Carbon Nanotube Nanocomposite Fabrication Using Casting And Hot Press Techniques

    Directory of Open Access Journals (Sweden)

    Park S.G.

    2015-06-01

    Full Text Available Biodegradable advanced polymer composites have recently received a large amount of attention. The present study aimed to design poly(lactic acid multiwalled carbon nanotube nanocomposites (PLA/MWCNTs using a simple fabrication technique. A PLA sheet was first dissolved in dichloromethane, and MWCNTs were subsequently added at various concentrations (0.5, 1.5 and 5% while applying shear strain stirring to achieve dispersion of carbon nanotubes (CNTs. These solutions were then molded and a hot press was used to generate sheets free of voids with entrapped solvent. The prepared samples were characterized using field emission scanning electron microscopy (FE-SEM, x-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, and thermogravimetric analysis (TGA. Our data showed composite samples free of defects and voids, indicating that the hot press is capable of generating sufficiently compact polymer matrices. Additionally, TGA and FTIR showed significant bonding interactions between the PLA matrix and the nano-fillers. Collectively, our results suggest that incorporation of CNTs as nano-fillers into biodegradable polymers may have multiple applications in many different sectors.

  17. Influence of Sintering Temperature on the Microstructure and Mechanical Properties of In Situ Reinforced Titanium Composites by Inductive Hot Pressing

    Directory of Open Access Journals (Sweden)

    Cristina Arévalo

    2016-11-01

    Full Text Available This research is focused on the influence of processing temperature on titanium matrix composites reinforced through Ti, Al, and B4C reactions. In order to investigate the effect of Ti-Al based intermetallic compounds on the properties of the composites, aluminum powder was incorporated into the starting materials. In this way, in situ TixAly were expected to form as well as TiB and TiC. The specimens were fabricated by the powder metallurgy technique known as inductive hot pressing (iHP, using a temperature range between 900 °C and 1400 °C, at 40 MPa for 5 min. Raising the inductive hot pressing temperature may affect the microstructure and properties of the composites. Consequently, the variations of the reinforcing phases were investigated. X-ray diffraction, microstructural analysis, and mechanical properties (Young’s modulus and hardness of the specimens were carried out to evaluate and determine the significant influence of the processing temperature on the behavior of the composites.

  18. Investigation of a hot-pressed Nb–Ti–Al alloy: Mechanical alloying, microstructure and mechanical property

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhiwu; Wei, Hua; Zhang, Hongyu; Jin, Tao; Sun, Xiaofeng; Zheng, Qi, E-mail: qzheng@imr.ac.cn

    2016-01-10

    The Nb–23Ti–15Al (at%) alloy was prepared by mechanical alloying (MA) and hot-pressing (HPing). The microstructure evolution of powder particles during MA and its influence on the microstructure and mechanical properties of the hot-pressed (HPed) alloy have been investigated. The powder and HPed alloy were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicate that particle size increases in the first stage and then decreases in the second stage during MA; as milling speed increases, mechanically alloyed (MAed) powder with convoluted elemental lamellae, homogeneous Nb solid-solution and an amorphous phase could be obtained respectively in 24 h. Higher homogeneity in microstructure and composition of the MAed powder particles promotes the precipitation of the δ phase and refines the β and Ti(O,C) phases in the HPed alloy. Moreover, due to the phase equilibrium changes caused by Fe and Cr in the amorphous powder, σ phase appears in the alloy as a stable phase instead of the δ phase. Properly MAed powder contributes to higher hardness of the HPed alloy, for reasons of microstructure refinement and sufficient precipitating of strengthening phases.

  19. Investigation of a hot-pressed Nb–Ti–Al alloy: Mechanical alloying, microstructure and mechanical property

    International Nuclear Information System (INIS)

    Shi, Zhiwu; Wei, Hua; Zhang, Hongyu; Jin, Tao; Sun, Xiaofeng; Zheng, Qi

    2016-01-01

    The Nb–23Ti–15Al (at%) alloy was prepared by mechanical alloying (MA) and hot-pressing (HPing). The microstructure evolution of powder particles during MA and its influence on the microstructure and mechanical properties of the hot-pressed (HPed) alloy have been investigated. The powder and HPed alloy were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results indicate that particle size increases in the first stage and then decreases in the second stage during MA; as milling speed increases, mechanically alloyed (MAed) powder with convoluted elemental lamellae, homogeneous Nb solid-solution and an amorphous phase could be obtained respectively in 24 h. Higher homogeneity in microstructure and composition of the MAed powder particles promotes the precipitation of the δ phase and refines the β and Ti(O,C) phases in the HPed alloy. Moreover, due to the phase equilibrium changes caused by Fe and Cr in the amorphous powder, σ phase appears in the alloy as a stable phase instead of the δ phase. Properly MAed powder contributes to higher hardness of the HPed alloy, for reasons of microstructure refinement and sufficient precipitating of strengthening phases.

  20. Microstructure, mechanical and tribological behavior of hot-pressed mechanically alloyed Al–Zn–Mg–Cu powders

    International Nuclear Information System (INIS)

    Azimi, A.; Fallahdoost, H.; Nejadseyfi, O.

    2015-01-01

    Highlights: • Nanocrystalline Al7050 alloy was synthesized by mechanical alloying. • Longer milling time led to increasing porosity in hot-pressed samples. • Significant improvement in strength and wear resistance was obtained by increasing the milling time up to 40 h. - Abstract: This research focuses on the preparation of Al7050 alloy via mechanical alloying and hot pressing techniques. The effect of milling time on the microstructure and densification response was investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). Furthermore, the mechanical properties of the samples including microhardness, compression strength, and wear resistance were examined as a function of milling time. The results of the experiments proved that by increasing the milling time the crystallite size was reduced, which has a significant effect on improving the mechanical properties. In addition, porosity formation increased when the milling time was increased due to reduction of the compressibility of finer particles. By increasing the milling time to more than 40 h, a relatively invariable crystallite size was obtained and it was observed that the porosities expanded in the samples. Therefore, the compressive strength, hardness, and wear resistance were enhanced up to 40 h milling time and then the strengthening effect was relatively diminished. On observing surfaces with SEM, the dominant wear mechanism was recognized as abrasion, delamination and adhesion

  1. Improvement of linerboard compressive strength by hot-pressing and addition of recovered lignin from spent pulping liquor

    Directory of Open Access Journals (Sweden)

    Saidan Motasem N.

    2015-01-01

    Full Text Available This paper evaluates the effect of addition of precipitated lignin, from spent pulping black liquor, to a wet single-ply linerboard handsheet followed by hot-pressing at different temperatures, on the improvement of its compressive strength. Linerboard handsheets for testing the effect of lignin addition were prepared so that the lignin-modified sheets would have the same basis weights as the control handsheets. Both the commercial and the black liquor lignin were added as a powder to wet handsheets after couching from the handsheet mold. The experiments and testing of the physical and strength properties of dried handsheets were conducted according to TAPPI test methods. The results revealed that the addition of the recovered lignin (at pH of 2 to the wet handsheet followed by hot-pressing at 150°C increased the compressive strength of linerboard handsheets by 10% to 20% above that for handsheets made without the addition of lignin. The same results were achieved using purchased lignin. However, with a 16% addition to linerboard, purchased lignin would be too expensive. These results indicate that inclusion of kraft lignin in linerboard sheets could be proved as an attractive option to reduce linerboard basis weight.

  2. Microstructures and mechanical properties of Fe-28Al-5Cr/TiC composites produced by hot-pressing sintering

    International Nuclear Information System (INIS)

    Zhang Xinghua; Yang Jun; Ma Jiqiang; Bi Qinling; Cheng Jun; Liang Yongmin; Liu Weimin

    2011-01-01

    Highlights: → The near fully dense Fe-28Al-5Cr/TiC composites are produced by hot-pressing sintering. → All the materials exhibit high compressive and bending strength. → Compressive strength increases but bending strength and ductility diminish with rising TiC amount in the composites. → Wear resistance significantly increases with rising TiC amount. - Abstract: The mechanical properties and microstructures of Fe-28Al-5Cr based composites reinforced with 15, 25, 35, 50 wt.% TiC ceramic particle, produced by hot-pressing sintering method, were investigated. The relative density of all the composites was up to 99%. The distribution of TiC was uniform in the composites. Results of XRD analysis showed that the composites were composed of TiC and disorder Fe 3 Al phases. All the materials exhibited very high strength of 1200-2000 MPa. The hardness and compressive strength of the composites increased obviously but compressive strain decreased gradually except 50% composite with increasing TiC content. The bending strength and deflection of the composites decreased significantly with increasing TiC content. The bending fracture surfaces of all the materials were examined using scanning electron microscopy (SEM). The fracture mode transformed gradually from tough dimple fracture mode to brittle cleavage facets crack mode with the increase of TiC content. Wear resistance of the Fe-28Al-5Cr alloy was also significantly improved by addition of TiC.

  3. New concept bioceramics composed of octacalcium phosphate (OCP) and dicarboxylic acid-intercalated OCP via hydrothermal hot-pressing

    Energy Technology Data Exchange (ETDEWEB)

    Ishihara, Shiho [Graduate School of Engineering, Osaka Prefecture University (Japan); Matsumoto, Takuya [Graduate School of Dentistry, Osaka University (Japan); Onoki, Takamasa, E-mail: onoki@mtr.osakafu-u.ac.jp [Graduate School of Engineering, Osaka Prefecture University (Japan); Sohmura, Taiji [Graduate School of Dentistry, Osaka University (Japan); Nakahira, Atsushi [Graduate School of Engineering, Osaka Prefecture University (Japan)

    2009-08-01

    Octacalcium phosphate (OCP) and adipic acid-intercalated complexed OCP (Adi-OCP) were synthesized. Moreover, we made ceramic bodies out of them through a hydrothermal hot-pressing (HHP) method. Characteristic features of both the powder and ceramics were investigated by the X-ray diffraction method (XRD). Surface morphology of the ceramics was observed by scanning electron microscopy (SEM). Density, compressive strength and pore size distribution of the ceramics were measured. Crystalline structure of the newly developed OCP ceramics had no phase transformation from the starting materials. Moreover, the newly developed OCP ceramics had good mechanical properties only through the HHP treatment with a temperature as low as 110 deg. C. In order to evaluate bioactivity, the ceramics were immersed in simulating body fluid (SBF). It was predicted that OCP and Adi-OCP had better bioactivity than that of conventional HAp ceramics.

  4. A trapped field of >3 T in bulk MgB2 fabricated by uniaxial hot pressing

    International Nuclear Information System (INIS)

    Durrell, J H; Dennis, A; Shi, Y; Xu, Z; Campbell, A M; Babu, N Hari; Cardwell, D A; Dancer, C E J; Todd, R I; Grovenor, C R M

    2012-01-01

    A trapped field of over 3 T has been measured at 17.5 K in a magnetized stack of two disc-shaped bulk MgB 2 superconductors of diameter 25 mm and thickness 5.4 mm. The bulk MgB 2 samples were fabricated by uniaxial hot pressing, which is a readily scalable, industrial technique, to 91% of their maximum theoretical density. The macroscopic critical current density derived from the trapped field data using the Biot–Savart law is consistent with the measured local critical current density. From this we conclude that critical current density, and therefore trapped field performance, is limited by the flux pinning available in MgB 2 , rather than by lack of connectivity. This suggests strongly that both increasing sample size and enhancing pinning through doping will allow further increases in trapped field performance of bulk MgB 2 . (rapid communication)

  5. Mechanochemical Effects on the Synthesis of Copper Orthophosphate and cyclo-Tetraphosphate Bulks by the Hydrothermal Hot Pressing Method

    Directory of Open Access Journals (Sweden)

    Isao Tanaka

    2009-01-01

    Full Text Available Copper orthophosphate, Cu3(PO42, and cyclo-tetraphosphates, Cu2P4O12, were synthesized using phosphoric acid and basic copper carbonate, and then treated with a planetary mill for up to 360 minutes. The un-milled and milled samples were characterized by X-ray diffraction (XRD and Fourier transform infrared (FT-IR spectroscopy. SEM images, particle size distribution, specific surface area, UV-Vis reflectance spectra were also used to evaluate the materials. The un-milled and milled materials were used to fabricate copper phosphate bulks by a hydrothermal hot pressing method. The influence of powder condition on the sintering behavior of the copper phosphates was studied.

  6. Intergranular phase of the Si3 N4 hot pressed with Mg O/Y2 O3

    International Nuclear Information System (INIS)

    Costa, Celio A.; Todd, Judith A.

    1997-01-01

    Monolithic and composite Si 3 N 4 hot-pressed with 3% Mgo or 6% Y 2 O 3 were analyzed with X-ray diffraction and transmission electron microscopy. The results showed materials to be composed of β-Si 3 N 4 grains and an intergranular phase which was partially crystalline and partially amorphous. For the materials sintered with Mg O, the identification of the intergranular phase was not conclusive. For the materials sintered with Y 2 O 3 . It was observed that the amount of intergranular crystalline phase decreased as whiskers were added to the material and the intergranular crystalline part had a crystallographic structure similar to yttrium-silicon-oxide-nitride family. (author)

  7. New concept bioceramics composed of octacalcium phosphate (OCP) and dicarboxylic acid-intercalated OCP via hydrothermal hot-pressing

    International Nuclear Information System (INIS)

    Ishihara, Shiho; Matsumoto, Takuya; Onoki, Takamasa; Sohmura, Taiji; Nakahira, Atsushi

    2009-01-01

    Octacalcium phosphate (OCP) and adipic acid-intercalated complexed OCP (Adi-OCP) were synthesized. Moreover, we made ceramic bodies out of them through a hydrothermal hot-pressing (HHP) method. Characteristic features of both the powder and ceramics were investigated by the X-ray diffraction method (XRD). Surface morphology of the ceramics was observed by scanning electron microscopy (SEM). Density, compressive strength and pore size distribution of the ceramics were measured. Crystalline structure of the newly developed OCP ceramics had no phase transformation from the starting materials. Moreover, the newly developed OCP ceramics had good mechanical properties only through the HHP treatment with a temperature as low as 110 deg. C. In order to evaluate bioactivity, the ceramics were immersed in simulating body fluid (SBF). It was predicted that OCP and Adi-OCP had better bioactivity than that of conventional HAp ceramics.

  8. Corrosion and wear behavior of functionally graded Al2024/SiC composites produced by hot pressing and consolidation

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, Fatih; Canakci, Aykut, E-mail: aykut@ktu.edu.tr; Varol, Temel; Ozkaya, Serdar

    2015-09-25

    Highlights: • Functionally graded Al2024/SiC composites were produced by hot pressing. • Effect of the number of graded layers was investigated on the corrosion behavior. • Functionally graded composites has the most corrosion resistant than composites. • Wear mechanisms of Al2024/SiC composites were explained. - Abstract: Functionally graded Al2024/SiC composites (FGMs) with varying percentage of SiC (30–60%) were produced by hot pressing and consolidation method. The effects of SiC content and number of layers of Al2024/SiC FGMs on the corrosion and wear behaviors were investigated. The microstructures of these composites were characterized by a scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The corrosion performances of composites were evaluated by potentiodynamic polarization scans in 3.5% NaCl solution. Corrosion experiments shows that corrosion rate (1109 mpy) of two layered FGMs which containing 50 wt.% SiC were much higher than Al2024 matrix (2569 mpy) and Al2024/50 wt.% SiC composite (2201 mpy). Mechanical properties of these composites were evaluated by microhardness measurements and ball-on-disk wear tests. As the applied load change from 15 to 20 N, the wear rates of the Al2024 increased significantly and wear mechanism transformed from mild to severe wear regime. It has been shown that Al2024/40 wt.% SiC composite has lower wear rate where adhesive and abrasive wear mechanisms play a major role.

  9. Effect of deformation ratios on grain alignment and magnetic properties of hot pressing/hot deformation Nd-Fe-B magnets

    Science.gov (United States)

    Guo, Zhaohui; Li, Mengyu; Wang, Junming; Jing, Zheng; Yue, Ming; Zhu, Minggang; Li, Wei

    2018-05-01

    The magnetic properties, microstructure and orientation degrees of hot pressing magnet and hot deformation Nd-Fe-B magnets with different deformation ratios have been investigated in this paper. The remanence (Br) and maximum magnetic energy product ((BH)max) were enhanced gradually with the deformation ratio increasing from 0% to 70%, whereas the coercivity (HCj) decreased. The scanning electron microscopy (SEM) images of fractured surfaces parallel to the pressure direction during hot deformation show that the grains tend to extend perpendicularly to the c-axes of Nd2Fe14B grains under the pressure, and the aspect ratios of the grains increase with the increase of deformation ratio. Besides, the compression stress induces the long axis of grains to rotate and the angle (θ) between c-axis and pressure direction decreases. The X-ray diffraction (XRD) patterns reveal that orientation degree improves with the increase of deformation ratio, agreeing well with the SEM results. The hot deformation magnet with a deformation ratio of 70% has the best Br and (BH)max, and the magnetic properties are as followed: Br=1.40 T, HCj=10.73 kOe, (BH)max=42.30 MGOe.

  10. Atom Probe Tomography of Phase and Grain Boundaries in Experimentally-Deformed and Hot-Pressed Wehrlite

    Science.gov (United States)

    Cukjati, J.; Parman, S. W.; Cooper, R. F.; Zhao, N.

    2017-12-01

    Atom probe tomography (APT) was used to characterize the chemistry of three grain boundaries: an olivine-olivine (ol-ol) and olivine-clinopyroxene (ol-cpx) boundary in fine-grained experimentally-deformed wehrlite and an ol-cpx boundary in a fine-grained, hot-pressed wehrlite. Grain boundaries were extracted and formed into APT tips using a focused ion beam (FIB). The tips were analyzed in a reflectron-equipped LEAP4000HR (Harvard University) at 1% or 0.5% detection rate, 5pJ laser energy and 100kHz pulse rate. Total ion counts are between 40 and 100 million per tip. Examination of grain and phase boundaries in wehrlite are of interest since slow-diffusing and olivine-incompatible cations present in cpx (e.g. Ca and Al) may control diffusion-accommodated grain boundary sliding and affect mantle rheology (Sundberg & Cooper, 2008). At steady state, ol-cpx aggregates are weaker than either ol or cpx end member, the results of which are not currently well-explained. We investigate grain boundary widths to understand the transport of olivine-incompatible elements. Widths of grain/phase boundary chemical segregation are between 3nm and 6nm for deformed ol-ol and ol-cpx samples; minimally-deformed (hot-pressed) samples having slightly wider chemical segregation widths. Chemical segregation widths were determined from profiles of Na, Al, P, Cl, K, Ca, or Ni, although not all listed elements can be used for all samples (e.g. Na, K segregation profiles can only be observed for ol-ol sample). These estimates are consistent with prior estimates of grain boundary segregation by atom probe tomography on ol-ol and opx-opx samples (Bachhav et al., 2015) and are less than ol-ol interface widths analyzed by STEM/EDX (Hiraga, Anderson, & Kohlstedt, 2007). STEM/EDX will be performed on deformed wehrlite to investigate chemical profile as a function of applied stress orientation and at length scales between those observable by APT and EPMA. Determination of phase boundary chemistry and

  11. Volatile organic compound emissions during hot-pressing of southern pine particleboard : panel size effects and trade-off between press time and temperature

    Science.gov (United States)

    Wenlong Wang; Douglas J. Gardner; Melissa G.D. Baumann

    2002-01-01

    In previous research, it was shown that decreasing either press temperature or press time generally resulted in decreased volatile organic compound (VOC) emissions during the hot-pressing of southern pine particleboard. However, because it is impossible to reduce both pressing time and temperature while maintaining panel physical and mechanical properties, this study...

  12. The Effect of Veneer Layers on the Bending Shear Strength and Delamination of Laminated Veneer Lumber (LVL) from Oil Palm Trunk (OPT)

    Science.gov (United States)

    Jamaludin, M. A.; Nordin, K.; Bahari, S. A.; Ahmad, M.

    2010-03-01

    The aim of this study was to evaluate the effects of the number of veneer layers on the bending shear strength and delamination of Laminated Veneer Lumber (LVL) from oil palm trunk (OPT). Five (5), Six (6) and Seven (7) veneer layers of OPT LVL were manufactured. The dimension of the boards was 45 cm by 45 cm by 1.9 cm. The boards were hot pressed for 13 minutes at a pressure of 31 kgf per m2. Urea formaldehyde (UF) supplied by a local adhesive manufacturer was used as the binder for the boards. The bending shear tests consisted of the edgewise and flatwise tests, whereas the delamination test consisted of the cold and hot water boil tests. The preparation of the test specimens and tests set-up was in accordance to the Japanese Standards, JAS-1991 [1]. Six replications were used for each test. The results were analyzed by Analysis of Variance (ANOVA) using the Duncan's Multiple Range Test to test for significant differences. The results indicated that as the number of layers increased the strength also increased. All the boards passed the standard. The difference in strength between the different types of samples was significant at 95 percent confidence level. Bending shear failures were primarily in the veneers. It is possible to use the boards as light weight interior building and furniture components. Over the years, the supply of quality timber resources from the natural forest has decrease as the wood-based industry experienced rapid growth. The supply of rubberwood for the furniture industry is also decreasing as a result of increase latex price. Accordingly, OPT LVL can be an alternative or supplementary raw material for the wood-based industry.

  13. Cold-pressed and hot-pressed rapeseed oil: The effects of roasting and seed moisture on the antioxi- dant activity, canolol, and tocopherol level.

    Science.gov (United States)

    Siger, Aleksander; Józefiak, Marta; Górnaś, Paweł

    2017-01-01

    The paper looks at the levels of canolol, tocopherols and antioxidant activity in cold-pressed and hot-pressed rapeseed oils produced from seeds of various moisture levels (5%, 7.5%, and 10%). The paper also considers the effects of seed roasting on the levels of these compounds. The material used for the tests was rapeseed cv. Adrianna. The quality of the oils obtained is determined using peroxide and acid values. The levels of canolol and tocopherols are analyzed using HPLC. The DPPH radical-scavenging activity method for oil samples and phenolic extract from oils was used. It has been demonstrated that the oils produced from rapeseeds with a 5% moisture content, and   in particular from cold-pressed oils, were characterized by the lowest peroxide values. Cold-pressed oils produced from rapeseeds with a 5% moisture content were characterized by higher levels of tocopherols and plastochromanol-8. In the case of hot-pressed oils, the highest levels of tocopherols were found in oils pro- duced from seeds with a 7.5% moisture content, and the greatest amount of PC-8 (more than 4 mg/100 g) was found in oils produced from seeds with a 10% moisture content. Hot-pressed oils have been shown to have higher levels of these compounds than cold-pressed oils. Both roasting and hot pressing led to an increase in the amount of canolol in the oils investigated. When analysing the antioxidant activity of the oils and phenolic extracts it was shown that phenolic compounds are responsible for approx. 10% of total antioxidant activity. Various levels of biologically active compounds were shown to be present in the rapeseed oil obtained from raw materials of a varying moisture content. The type of pressing process (cold-pressing or hot-pressing) and whether the seeds have undergone roasting has also been shown to affect the resulting oil and the level of native antioxidants it contains.

  14. Hot Deformation Behavior and Pulse Current Auxiliary Isothermal Forging of Hot Pressing Sintering TiAl Based Alloys.

    Science.gov (United States)

    Shi, Chengcheng; Jiang, Shaosong; Zhang, Kaifeng

    2017-12-16

    This paper focuses on the fabrication of as-forged Ti46.5Al2Cr1.8Nb-(W, B) alloy via pulse current auxiliary isothermal forging (PCIF). The starting material composed of near gamma (NG) microstructure was fabricated by adopting pre-alloyed powders via hot pressing sintering (HPS) at 1300 °C. Isothermal compression tests were conducted at a strain rate range of 0.001-0.1 s -1 and a temperature range of 1125-1275 °C to establish the constitutive model and processing map. The optimal hot deformation parameters were successfully determined (in a strain rate range of 10 -3 -2.5 × 10 -3 s -1 and temperature range of 1130-1180 °C) based on the hot processing map and microstructure observation. Accordingly, an as-forged TiAl based alloy without cracks was successfully fabricated by PCIF processing at 1175 °C with a nominal strain rate of 10 -3 s -1 . Microstructure observation indicated that complete dynamic recrystallization (DRX) and phase transformation of γ→α₂ occurred during the PCIF process. The elongation of as-forged alloy was 136%, possessing a good secondary hot workability, while the sintered alloy was only 66% when tested at 900 °C with a strain rate of 2 × 10 -4 s -1 .

  15. Enhancement of mechanical strength in hot-pressed TiB2 composites by the addition of Fe and Ni

    International Nuclear Information System (INIS)

    Yen, C.F.; Yust, C.S.; Clark, G.W.

    1978-01-01

    Improvement in the fracture strength of TiB 2 composites through the addition of Fe and Ni is reported. Beam specimens containing up to 20 wt % of the metal component were fabricated by hot pressing above the eutectic temperature. Four point bending results indicated that the observed enhancement in strength was proportional to the vol % of the metal present. The results also revealed that TiB 2 --Ni composites have slightly better strength than TiB 2 --Fe samples at elevated temperatures, and that their strengths were consistently about twice that of pure TiB 2 . They also did not exhibit any serious degradation in strength up to 700 0 C. The fracture behavior was characterized using optical and scanning electron microscopy. The strengthening appears to be related to the presence of a metallic grain boundary phase between TiB 2 particles. The results further suggested that the formation of a special eutectic-like grain microstructure could render additional strengthening

  16. Vacuum hot-pressed beryllium and TiC dispersion strengthened tungsten alloy developments for ITER and future fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiang, E-mail: xliu@swip.ac.cn [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Chen, Jiming; Lian, Youyun; Wu, Jihong; Xu, Zengyu; Zhang, Nianman; Wang, Quanming; Duan, Xuro [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Wang, Zhanhong; Zhong, Jinming [Northwest Rare Metal Material Research Institute, CNMC, Ningxia Orient Group Co. Ltd.,No.119 Yejin Road, Shizuishan City, Ningxia,753000 (China)

    2013-11-15

    Beryllium and tungsten have been selected as the plasma facing materials of the ITER first wall (FW) and divertor chamber, respectively. China, as a participant in ITER, will share the manufacturing tasks of ITER first-wall mockups with the European Union and Russia. Therefore ITER-grade beryllium has been developed in China and a kind of vacuum hot-pressed (VHP) beryllium, CN-G01, was characterized for both physical, and thermo-mechanical properties and high heat flux performance, which indicated an equivalent performance to U.S. grade S-65C beryllium, a reference grade beryllium of ITER. Consequently CN-G01 beryllium has been accepted as the armor material of ITER-FW blankets. In addition, a modification of tungsten by TiC dispersion strengthening was investigated and a W–TiC alloy with TiC content of 0.1 wt.% has been developed. Both surface hardness and recrystallization measurements indicate its re-crystallization temperature approximately at 1773 K. Deuterium retention and thermal desorption behaviors of pure tungsten and the TiC alloy were also measured by deuterium ion irradiation of 1.7 keV energy to the fluence of 0.5–5 × 10{sup 18} D/cm{sup 2}; a main desorption peak at around 573 K was found and no significant difference was observed between pure tungsten and the tungsten alloy. Further characterization of the tungsten alloy is in progress.

  17. Effect of sintering temperature and boron carbide content on the wear behavior of hot pressed diamond cutting segments

    Directory of Open Access Journals (Sweden)

    Islak S.

    2015-01-01

    Full Text Available The aim of this study was to investigate the effect of sintering temperature and boron carbide content on wear behavior of diamond cutting segments. For this purpose, the segments contained 2, 5 and 10 wt.% B4C were prepared by hot pressing process carried out under a pressure of 35 MPa, at 600, 650 and 700 °C for 3 minutes. The transverse rupture strength (TRS of the segments was assessed using a three-point bending test. Ankara andesite stone was cut to examine the wear behavior of segments with boron carbide. Microstructure, surfaces of wear and fracture of segments were determined by scanning electron microscopy (SEM-EDS, and X-ray diffraction (XRD analysis. As a result, the wear rate decreased significantly in the 0-5 wt.% B4C contents, while it increased in the 5-10 wt.% B4C contents. With increase in sintering temperature, the wear rate decreased due to the hard matrix.

  18. Investigation of Wear Behavior of Aluminum Matrix Composite Reinforced by Al2O3 and Produced by Hot Pressing Process

    Directory of Open Access Journals (Sweden)

    Halil ARIK

    2017-12-01

    Full Text Available In this study, Al powder produced by gas atomization technique has 72.06 µm average particle size and 99 % purity was mixed with as a reinforcement Al2O3 has 99.52% purity and 45 submicron particle size in a high energy ball mill for two hours. In order to obtain disk samples with 30 mm diameter and 6 mm thick mixed powders, after the characterization of particle size and morphology, were compacted in a single action press. Compaction process were carried out from mixed powders by hot pressing at 200 MPa pressure and 550 °C temperature for two hours. Then microstructural analysis, hardness and density measurements of powder metal composite parts were performed. After, the characterization of samples abrasion wear tests were performed according to ASTM-G99-05 by using TRIBOMETER T10/20 ball-on-disk abrasive wearing device. After the abrasive wear test of aluminum and composite powder metal parts produced under the identical test parameters, test results were compared and effect of Al2O3 on the wear properties of composite materials was exhibited. The test results showed that the composite parts have 62 % extra harness and better abrasion wear performance according to aluminum powder metal parts produced and tested under the identical conditions

  19. Strength-toughness relations in sintered and isostatically hot-pressed ZrO2-toughened Al2O3

    International Nuclear Information System (INIS)

    Hori, S.; Yoshimura, M.; Somiya, S.

    1986-01-01

    The fracture toughness of fine-grained undoped ZrO 2 -toughened Al 2 O 3 (ZTA) was essentially unchanged by post-sintering hot isostatic pressing and increased monotonically with ZrO 2 additions up to 25 wt%. The strength of ZTA with 5 to 15 wt% tetragonal ZrO 2 , which depended monotonically on the amount of ZrO 2 present before hot isostatic pressing, was increased by pressing but became almost constant between 5 and 15 wt% ZrO 2 addition. The strength appeared to be controlled by pores before pressing and by surface flaws after pressing; the size of flaws after pressing increased with ZrO 2 content. The strength of ZTA containing mostly monoclinic ZrO 2 (20 to 25 wt%) remained almost constant despite the noticeable density increase upon hot isostatic pressing because the strength was controlled by preexisting microcracks whose extent did not change on postsintering pressing. These strength-toughness relations in sintered and isostatically hot-pressed ZTA are explained on the basis of R-curve behavior. The importance of the contribution of microcracks to the toughness of ZTA is emphasized

  20. Study on the isothermal oxidation behavior in air of Ti3AlC2 sintered by hot pressing

    Institute of Scientific and Technical Information of China (English)

    XU Xuewen; LI Yangxian; MEI Bingchu; ZHU Jiaoqun; LIU Heyan; QU Jingping

    2006-01-01

    The isothermal oxidation behavior at 900―1300℃ for 20 h in air of bulk Ti3AlC2 with 2.8 wt% TiC sintered by means of hot pressing was investigated in the work. The isothermal oxidation behavior generally followed a parabolic rate law. The parabolic rate constants increased from 1.39×10-10 kg2·m-4·s-1 at 900℃ to 5.56×10-9 kg2·m-4·s-1 at 1300℃. The calculated activation energy was 136.45 kJ/mol. It was demonstrated that Ti3AlC2 had excellent oxidation resistance due to the continuous, dense and adhesive protect scales consisted of a mass of α-Al2O3 and a little of TiO2 and/or Al2TiO5. In principle, the oxide scale was grown by the inward diffusion of O2- and the outward diffusion of Ti4+ and Al3+. The rapid outward diffusion of cations usually resulted in the formation of cracks, gaps, and holes.

  1. Interfacial layers evolution during annealing in Ti-Al multi-laminated composite processed using hot press and roll bonding

    Science.gov (United States)

    Assari, A. H.; Eghbali, B.

    2016-09-01

    Ti-Al multi-laminated composites have great potential in high strength and low weight structures. In the present study, tri-layer Ti-Al composite was synthesized by hot press bonding under 40 MPa at 570 °C for 1 h and subsequent hot roll bonding at about 450 °C. This process was conducted in two accumulative passes to 30% and to 67% thickness reduction in initial and final passes, respectively. Then, the final annealing treatments were done at 550, 600, 650, 700 and 750 °C for 2, 4 and 6 h. Investigations on microstructural evolution and thickening of interfacial layers were performed by scanning electron microscopes, energy dispersive spectrometer, X-ray diffraction and micro-hardness tests. The results showed that the thickening of diffusion layers corresponds to amount of deformation. In addition to thickening of the diffusion layers, the thickness of aluminum layers decreased and after annealing treatment at 750 °C for 6 h the aluminum layers were consumed entirely, which occurred because of the enhanced interdiffusion of Ti and Al elements. Scanning electron microscope equipped with energy dispersive spectrometer showed that the sequence of interfacial layers as Ti3Al-TiAl-TiAl2-TiAl3 which are believed to be the result of thermodynamic and kinetic of phase formation. Micro-hardness results presented the variation profile in accordance with the sequence of intermetallic phases and their different structures.

  2. Thermoelectric Properties of Cu-doped Bi2-xSbxTe3 Prepared by Encapsulated Melting and Hot Pressing

    Science.gov (United States)

    Jung, Woo-Jin; Kim, Il-Ho

    2018-03-01

    P-type Bi2-xSbxTe3:Cum (x = 1.5-1.7 and m = 0.002-0.003) solid solutions were synthesized using encapsulated melting and were consolidated using hot pressing. The effects of Sb substitution and Cu doping on the charge transport and thermoelectric properties were examined. The lattice constants decreased with increasing Sb and Cu contents. As the amount of Sb substitution and Cu doping was increased, the electrical conductivity increased, and the Seebeck coefficient decreased owing to the increase in the carrier concentration. All specimens exhibited degenerate semiconductor characteristics and positive Hall and Seebeck coefficients, indicating p-type conduction. The increased Sb substitution caused a shift in the onset temperature of the intrinsic transition and bipolar conduction to higher temperatures. The electronic thermal conductivity increased with increasing Sb and Cu contents owing to the increase in the carrier concentration, while the lattice thermal conductivity slightly decreased due to alloy scattering. A maximum figure of merit, ZTmax = 1.25, was achieved at 373 K for Bi0.4Sb1.6Te3:Cu0.003.

  3. Silver as a highly effective bonding layer for lead telluride thermoelectric modules assembled by rapid hot-pressing

    International Nuclear Information System (INIS)

    Li, C.C.; Drymiotis, F.; Liao, L.L.; Dai, M.J.; Liu, C.K.; Chen, C.L.; Chen, Y.Y.; Kao, C.R.; Snyder, G.J.

    2015-01-01

    Highlights: • Ag serves as a promising bonding material for PbTe operating at T Hot ⩽ 400 °C. • The Ag foils reacted vigorously with PbTe to form Ag 2 Te at 550 °C. • The Seebeck coefficient of Ag/PbTe/Ag is slightly higher than that of pure PbTe. • A cost-effective way for long-term operations at high temperature. - Abstract: We use the rapid hot-pressing method to bond Ag foil onto pure PbTe in order to assess its effectiveness as a bonding layer material for thermoelectric module applications. Scanning electron microscopy and X-ray diffraction are employed to examine intermetallic compound formation and microstructure evolution during isothermal aging at 400 °C and 550 °C. We find that Ag is a promising bonding material for PbTe modules operating at T Hot ⩽ 400 °C. Additionally, our approach highlights a highly effective and inexpensive method to metallize PbTe prior to module assembly

  4. Sintering of Si C by hot-pressing with addition of Al2O3 and concentrate of rare earths

    International Nuclear Information System (INIS)

    Hwang, M.K.; Silva, C.R.M.

    2004-01-01

    Silicon carbide (SiC) has essentially covalent bonds (∼88%). The high covalency bond is responsible for the good mechanical properties, although it induces a low self diffusion coefficient, making densification more difficult. For a successful densification is necessary to apply pressure on the samples, and/or the addition of sintering additives, which improves the densification. In this SiC samples with alumina (Al2O3) and concentrate of rare earth (CRE) addition were sintered by hot pressing in argon atmospheric at 20 MPa of pressure, heating rate of 20 deg C/min up to 1800 deg C and a dwell time of 1 h. Initially the CRE was calcined at 1000 deg C during 1 h. After that, three mixtures were prepared with distinct concentrations in high energy mill and the samples were sintered. The aim of this work is to improve SiC densification by the liquid phase formation during sintering owing to the additives reactions between itself. The pressure intensify the driving force for densification, taking the liquid phase to drain easier through the grain boundaries, making possible best accommodation and rearrangement of the grains. The application of the pressure on the samples during sintering contributes to improve densification and becomes possible sintering in lower temperature than conventional one. The phases of the sintered samples were analyzed by X-ray diffraction and the morphology were verified by scanning electron microscopy. (author)

  5. Hot-pressed geopolymer

    DEFF Research Database (Denmark)

    Ranjbar, Navid; Mehrali, Mohammad; Maheri, Mahmoud R.

    2017-01-01

    This research explores the use of simultaneous heating and pressing techniques in order to enhance the mechanical properties of fly ash (FA) based geopolymer under relatively low temperature conditions to ensure minimum-porosity. Four effective parameters of pressing force, alkali activator...

  6. Comparison of Ti(C,N)-based cermets processed by hot-pressing sintering and conventional pressureless sintering

    International Nuclear Information System (INIS)

    Xu, Qingzhong; Ai, Xing; Zhao, Jun; Qin, Weizhen; Wang, Yintao; Gong, Feng

    2015-01-01

    Highlights: • The HP sintered Ti(C,N)-based cermets exhibit high hardness with fine grain size. • The PLS sintered cermets possess high mechanical properties with low porosity. • The applied pressure can rearrange particles and contribute to grain refinement. • The heating rate can greatly affect the solid and liquid phase sintering of cermets. - Abstract: A suitable sintering method is important to obtain the Ti(C,N)-based cermets with superior properties. In this paper, Ti(C,N)-based cermets were fabricated by hot-pressing sintering (HP) and conventional pressureless sintering (PLS) technology, respectively, to investigate the influence of different sintering methods on the microstructure and mechanical properties of cermets materials. The microstructure, fracture morphology, indention cracks and phase composition were observed and detected using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The transverse rupture strength (TRS), Vickers hardness (HV) and fracture toughness (K IC ) were also measured. The results reveal that all of the Ti(C,N)-based cermets exhibit core–rim microstructures with black cores, white cores and grey rims embedded into metal binder phases. The grain size of the samples fabricated by HP is much finer and the structure is more compact than those fabricated by PLS, while there exist pores in the HP sintered samples. The sintering process has no influence on the phase composition of cermets, but affects the phase content and crystallinity. The samples fabricated by PLS present higher transverse rupture strength, fracture toughness and density than samples fabricated by HP. However, the HP sintered samples possess a higher hardness

  7. Effects of internal gas pressure and microstructure on the mechanisms of hot-pressing and swelling in ceramics. Progress report, June 1, 1976--March 31, 1977

    International Nuclear Information System (INIS)

    Solomon, A.A.

    1977-02-01

    The low temperature isostatic pressurization system has been completed, operated successfully and calibrated. The new high temperature TD tungsten vessel and MoSi 2 element furnace system has also been designed and is presently under construction. Porous CoO single crystals have been grown using a ''skull melting'' process. Automated quantitative microscopy techniques are being developed using the KONTRON system to examine porosity evaluation during hot-pressing and sintering. Initial sintering experiments under variable isostatic pressures from 100 μm Hg to 2000 psi reveal no significant effect of ambient pressure. Nor were differences observed in sintering kinetics when either Helium or Argon were used as the pressurizing gas. Swelling experiments, conducted by reducing the ambient pressure after pore closure, revealed dramatic changes in density. The densification rates also appeared to depend on history, suggesting that mechanical deformation may play a dominant role in hot-pressing, at least during transients

  8. Kaji Eksperimental dan Simulasi Ansys 14.5 Perlakuan Serat Tandan Kosong Kelapa Sawit Serta Pembuatan Komposit Busa Polimer pada Proses Hot Press Menggunakan Alat Uji Tarik

    OpenAIRE

    Ginting, Enda Prananta

    2016-01-01

    Along the innovations of the field of materials, natural fibers are used as reinforcement materials composite which are the fibers greatly affect and determine the strength of the composite. This experimental study reported the empty fruit bunches of oil palm fiber’s treatment process and manufacture of polymeric foam composite spesimens in the process of hot press machine followed by a tensile test. The issues, that characteristic of composites reinforced fibers has a light weight and relati...

  9. Fracture strengths of chair-side-generated veneers cemented with glass fibers.

    Science.gov (United States)

    Turkaslan, S; Bagis, B; Akan, E; Mutluay, M M; Vallittu, P K

    2015-01-01

    CAD/CAM (computer-aided design and computer-aided manufacturing) systems have refreshed the idea of chair-side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of CAD/CAM-generated ceramic veneers. Therefore, this study compared the fracture strengths of ceramic veneers produced at chair side and cemented with or without glass fibers with those of composite veneers. Thirty intact mandibular incisors were randomly divided into three groups ( n = 10) and treated with CAD/CAM-fabricated veneers cemented with dual-cure composite resin luting cement (CRLC; Group 1), CAD/CAM-fabricated veneers cemented with a glass fiber network (GFN) and dual-cure CRLC (Group 2), and a direct particulate filler composite veneer constructed utilizing fiber and a restorative composite resin (Group 3). The specimens were tested with a universal testing machine after thermal cycling treatment. The loads at the start of fracture were the lowest for traditionally fabricated composite veneers and higher for CAD/CAM-generated. Veneers cemented either without or with the GFN. The failure initiation loads (N) for the veneers were 798.92 for Group 1, 836.27 for Group 2, and 585.93 for Group 3. The predominant failure mode is adhesive failure between the laminates and teeth for Group 1, cohesive failure in the luting layer for Group 2, and cohesive laminate failure for Group 3, which showed chipping and small fractures. Ceramic material is a reliable alternative for veneer construction at chair side. Fibers at the cementation interface may improve the clinical longevity and provide higher fracture strength values.

  10. Western hemlock as a veneer resource.

    Science.gov (United States)

    Thomas D. Fahey; Jr. Woodfin

    1982-01-01

    Presents recovery of veneer grade and volume from western hemlock from Oregon and Washington. Veneer grade recovery varied by grade and size of logs. Veneer volume recovered was about 45 percent of the cubic volume of the log and varied somewhat with log diameter.

  11. Developing and Evaluating Composites Based on Plantation Eucalyptus Rotary-cut Veneer and High-density Polyethylene Film as Novel Building Materials

    Directory of Open Access Journals (Sweden)

    Wei Song

    2016-02-01

    Full Text Available To achieve value-added utilizations of plantation timbers, eucalyptus veneer/high-density polyethylene film composites were prepared, with process-factors (PF (hot-pressing temperature, HT; hot-pressing duration, HD; hot-pressing pressure, HP; HDPE-film content, HC and composite-properties (CP (water-resistant bonding-strength, BS; modulus of rupture, MOR; modulus of elasticity, MOE investigated. According to thermal analyses, 140 to 180 °C was appropriate for HT. Based on statistical analyses, HD was easier to affect CP, while MOE was easier to be affected by PF. Quantitative relationships between PF and CP were determined by the neural-network (ANN modeling. In ANN simulation surveys, CP displayed Gaussian distributions (R2 > 0.9 when PF changed in current ranges, with positive correlations between BS and MOR (R2 ≈ 0.5. Combining ANN and the genetic-algorithm, optimal processes (HT, 160 °C; HD, 50 s/mm; HP, 1.3 MPa; HC, 6 layers were found, and optimal results (BS, 1.30 MPa; MOR, 86.94 MPa; MOE, 8.33 GPa were comparable to various reported poplar-plywoods. Microscopic images demonstrated that composite interfaces were formed by the mechanical interlocking. The optimal BS attained Chinese standards for water-resistant plywoods, so proposed composites can serve as water-resistant and formaldehyde-free building materials for furniture and interior design.

  12. Some properties of LVL composed of poplar and beech veneer and possibilities of their application for window frames

    Directory of Open Access Journals (Sweden)

    Zdravković Vladislav

    2017-01-01

    Full Text Available The subject of this paper was a research of physical and mechanical properties of LVL composed of peeled poplar veneers in core layers and only outer layers of beech peeled veneers, so as the examination of window frame glue joint strength produced of this material. LVL boards have been hot pressed in industrial conditions, using appropriate phenol formaldehyde (PP adhesive. Samples for corner window frame glue joint strength testing were glued with PVAc D4 class adhesive. Statistical analysis showed that there were significant differences both in moisture content and density of LVL boards regarding their thickness, while in the case of hardness this difference did not exist. Examinations of LVL glue line shear strength showed that both phenol formaldehyde (PP and PVAc D4 class adhesives fulfilled standard requirements. The results of corner window frame double tenon glue joint strength produced from combined poplar-beech veneer LVL indicated that such material could be used to produce window frame corner joint, strong enough to withstand the additional load, without an increase of the cross section.

  13. Fracture strengths of chair‑side‑generated veneers cemented with ...

    African Journals Online (AJOL)

    Introduction: CAD/CAM (computer‑aided design and computer‑aided manufacturing) systems have refreshed the idea of chair‑side production of restorations, but the fracture of ceramic veneers remains a problem. Cementation with glass fibers may improve the fracture strengths and affect the failure modes of ...

  14. UV curing of teak veneers for decorative panel

    International Nuclear Information System (INIS)

    Gatot Trimulyadi Rekso; Darsono

    1999-01-01

    The radiation curing of surface coating of teak veneers for decorative panels has been conducted by using ultra violet (UV) as radiation source. In this experiment teak wood veneer was use as a substrate. Epoxy acrylate (import product,) and unsaturated polyester (locally product) were used as coating materials after being added with difunctional monomer TPGDA, and photo-initiator darocur 1173 or irgacure 184. Irradiation was conducted using 80 watt/cm LTV source at conveyor speed of 3,0 m/min. Parameters observed were viscosity of coating materials, hardness, adhesion, appearance, abrasion and chemical resistance of cured films. In general the results showed that viscosity of the formulations based on epoxy acrylate and unsaturated polyester resin were effected by the storage. Film cured by LTV made of epoxy acrylate and unsaturated polyester on the teak veneer wood have the same adhesion and abrasion resistant properties but the hardness and chemical resistant of epoxy acrylate are better than unsaturated polyester. From the experiment result it can be concluded the unsaturated polyester (locally product) can be used as radiation curable material for coating teak veneer panels

  15. Microstructures and mechanical properties of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites prepared by vacuum hot-pressing sintering

    Energy Technology Data Exchange (ETDEWEB)

    Xiaosong, Jiang, E-mail: xsjiang@yeah.net [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Liu, Wanxia; Li, Jingrui [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Shao, Zhenyi [Department of Mechanical Engineering, Chengdu Technological University, Chengdu, Sichuan 610031 (China); Zhu, Degui [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    2015-01-05

    Highlights: • Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites were prepared using vacuum hot-pressing sintering. • Dispersions of MWCNTs were prepared using 10 μg/ml gallic acid aqueous solution. • MWCNTs content has no effect on generation of TiC and Cu{sub 9}Si to effect matrix’s performance. - Abstract: Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites were prepared by vacuum hot-pressing sintering. Microstructures and mechanical properties of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites with different multi-walled carbon nanotubes contents have been systematically investigated. The microstructures of the composites were examined by optical microscopy, X-ray diffraction, back scattered electron imaging, scanning electron microscope and energy dispersive spectrometer. The mechanical properties were determined from Brinell hardness and tensile tests. The results demonstrated that there was an optimum value of MWCNTs content which has an impact on microstructures and mechanical properties of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites. Based on MWCNTs content on properties and microstructure of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites, effects of MWCNTs on improvement of the composites and strengthening mechanism have been analyzed.

  16. Study on the process of sintering matrix metallic Fe-Cu-25%Nb and Fe-Cu-25%Co during hot pressing

    International Nuclear Information System (INIS)

    Batista, A.C.; Oliveira, H.C.P.; Souza, M.H.; Assis, P.S.

    2016-01-01

    The sintering process promotes densification and the evolution of the microstructure of the material, with consequent significant increase in hardness and mechanical strength. However, few studies show the influence of pressure and temperature during sintering by hot pressing. In this sense, this work aims to evaluate the microstructural changes and properties with the variation of pressure and temperature and the type suffered by sintering metal powders during sintering by hot pressing. For this, two samples were studied by changing the sintering parameters: 25% Fe-50% Cu-25% Nb and 25% Fe-50% Cu-25% Co. Samples were analyzed by SEM / EDS in order to check the morphology and the presence of pores, as well as the interaction between the metallic constituents of each sample by the EDS analysis in line. They also determined the relative density, porosity and Vickers hardness (HV5). At the end of the study it was concluded that niobium alloy composite element by sintering activated suffered together with the liquid phase sintering. For cobalt alloys were observed by liquid phase sintering. The increase in the severity of the sintering conditions (temperature and pressure) led to an improvement in physical and mechanical properties of the alloys, which indicates that these parameters are directly related to the mechanisms of diffusion in the sintering process, improving the properties and diffusivity between elements. (author)

  17. Evaluation of veneer yields and grades from yellow-poplar, white oak, and sweetgum from the southeast

    Science.gov (United States)

    Robert H. McAlister

    1980-01-01

    Dry volume yields and standard grades of veneer are given for yellow-poplar, sweetgum, and white oak by tree diameter and location within the stem. Results show that the typical stands of mixed southern pine and hardwood timer yield enough veneer to utilize almost 90 percent of the stand volume in the production of COM-PLY lumber and panels

  18. Arab Societal Awareness of Dental Veneers.

    Science.gov (United States)

    Alfouzan, Afnan; Al-Sanie, Aisha A; Al-Dhafiri, Reem A

    2018-03-01

    The aim of this study is to assess the Arab society's knowledge, awareness, and attitudes toward dental veneers. A cross-sectional study was performed by collecting data through an online questionnaire created using the Survey Monkey website and distributed among Middle Eastern societies through social media to ascertain participants' knowledge and awareness regarding dental veneers. The sample included Arab laypeople who were over 18 years old, to represent the awareness of the majority regarding dental veneers. The sample of this study included 1,332 subjects from different Middle Eastern nationalities, mainly Saudis, Kuwaitis, and Emiratis (15.6% of males and 84.4% of females). The results of this study showed that the total knowledge of dental veneers is 50.12%. The respondents with the highest level of knowledge acquired their information mainly from newspapers and magazines, followed by the Internet, then dentists, then social media, and, finally, friends and relatives. Cost was the only factor limiting 38.4% of subjects from receiving veneers, and 56% of the subjects would receive veneers if they were free of cost. In total, 72.6% of the respondents believed that veneers are currently overused. The knowledge and awareness of dental veneers were below a satisfactory level. Participants who relied on social media as a source of information had lower knowledge levels. This study emphasized the need for continual societal education regarding dental veneers.

  19. THERMOELECTRIC PROPERTIES OF HOT-PRESSED p-TYPE Mg2Si0.3Sn0.7 SOLID SOLUTION

    Directory of Open Access Journals (Sweden)

    G. N. Isachenko

    2014-05-01

    Full Text Available It is shown that thermoelectric energy conversion which gives the possibility for utilizing a low potential heat is one of the ways for adoption of energy-saving technologies; and semiconductor materials with p-type and n-type conductivities having high thermoelectric figure of merit are necessary for operation of thermoelectric generators. The paper deals with possibility of usage of the p-Mg2Si0.3Sn0.7 solid solution (with a nanostructured modification as a couple for the well studied thermoelectric material based on n-Mg2Si-Mg2Sn. A technological scheme for fabrication of heavily doped Mg2Si0.3Sn0.7 solid solution of p-type by hot pressing from nanopowder is developed. The given technology has made it possible to reduce duration of a homogeneous material fabrication and has improved its physical and chemical properties. The samples were made by three ways: direct fusion for polycrystals fabrication; hot pressing from microparticles; nanostructuring, i.e. hot pressing from nanoparticles. By X-ray diffraction it is shown that sizes of structural elements in the fabricated samples are about 40 nm. The probe technique is used for measurement of electric conductivity and Seebeck coefficient. The stationary absolute method is used for measurement of thermal conductivity. Thermoelectric figure of merit is defined by measured values of kinetic coefficients in the temperatures range of 77 – 800 K. It was demonstrated, that electric conductivity, Seebeck coefficient and the power factor do not depend practically on a way of solid solution preparation. Thermal conductivity of samples pressed from nanoparticles has appeared to be higher, than of samples, obtained by direct fusion; i.e. in this case nanostructuring has not led to increase of thermoelectric figure of merit. The conclusion is drawn, that polycrystalline semiconductor Mg2Si0.3Sn0.7 can be used as a p-branch for a thermoelectric generator though nanostructuring has not led to the figure of

  20. 反应热压制备TiC/Al复合材料的形成途径研究%Investigation on Formation Path of TiC/Al Composite Obtained by Reactive Hot-pressing Technology

    Institute of Scientific and Technical Information of China (English)

    宋谋胜; 冉茂武

    2012-01-01

    利用场激发反应热压合成技术研究了Al-Ti-C混合粉末体系制备TiC/Al产物的过程与致密性,并结合DSC实验分析了该体系合成TiC相的形成途径.结果表明,采用反应热压合成法完全能够制备较致密的TiC/Al复合材料.该体系形成TiC相的反应过程为:Ti(s)+3Al(s)=TiAl3(s)→Al(s)=Al(l) →Ti(s)+3 Al(l)=TiAl3(s)→ TiAl3(s)=TiAl3(1)→TiAl3(l)+C(s)=TiC(s)+ Al((l)).混合粉末中的Al不仅作为稀释剂降低体系的反应温度而细化TiC晶粒,还作为反应剂参与了整个反应进程.%Utilizing the field activation reactive hot-pressing (RHP) technology, the process and densificatian of TiC/Al products obtained from Al-Ti-C mixtures system were investigated, eoupied with the DSC experiment to analyze iht formation path of TiC phase in this system. The results show that the dense TiC/Al composite can be fully fabricated by the reactive hot-pressing method. The reaction process of the Al-Ti-C system to form TiC phase can be expressed: Ti(s)+3Al(s)= TiAl3(s) →Al(s)=Al(1)→Ti(,s)+3Al(1)=TiAl,(s)→TiAl3(s)=TiAl3(1)→TiAl3(l)+C(s)=T(C(s)+Al(1). Al in the mixtures plays an important role in serving not only as a diluent to decrease the reaction temperature and thus to refine the TiC grains, but also as an intermediate reactant to participate in the whole reaction process.

  1. Evaluation of a novel multiple phase veneering ceramic.

    Science.gov (United States)

    Sinthuprasirt, Pannapa; van Noort, Richard; Moorehead, Robert; Pollington, Sarah

    2015-04-01

    To produce a new veneering ceramic based on the production of a multiple phase glass-ceramic with improved performance in terms of strength and toughness. A composition of 60% leucite, 20% diopside and 20% feldspathic glass was prepared, blended and a heat treatment schedule of 930°C for 5 min was derived from differential thermal analysis (DTA) of the glasses. X-ray diffraction (XRD) and SEM analysis determined the crystalline phases and microstructure. Chemical solubility, biaxial flexural strength (BFS), fracture toughness, hardness, total transmittance and coefficient of thermal expansion (CTE) were all measured in comparison to a commercial veneering ceramic (VITA VM9). Thermal shock resistance of the leucite-diopside and VITA VM9 veneered onto a commercial high strength zirconia (Vita In-Ceram YZ) was also assessed. Statistical analysis was undertaken using Independent Samples t-test. Weibull analysis was employed to examine the reliability of the strength data. The mean chemical solubility was 6 μg/cm(2) for both ceramics (P=1.00). The mean BFS was 109 ± 8 MPa for leucite-diopside ceramic and 79 ± 11 MPa for VITA VM9 ceramic (P=0.01). Similarly, the leucite-diopside ceramic demonstrated a significantly higher fracture toughness and hardness. The average total transmittance was 46.3% for leucite-diopside ceramic and 39.8% for VITA VM9 (P=0.01). The leucite-diopside outperformed the VITA VM9 in terms of thermal shock resistance. Significance This novel veneering ceramic exhibits significant improvements in terms of mechanical properties, yet retains a high translucency and is the most appropriate choice as a veneering ceramic for a zirconia base core material. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. Stiffness and Density Analysis of Rotary Veneer Recovered from Six Species of Australian Plantation Hardwoods

    Directory of Open Access Journals (Sweden)

    Robert Lee McGavin

    2015-08-01

    Full Text Available Commercial interest in Australian hardwood plantations is increasing. The timber industry is investigating alternative supplies of forest resources, and the plantation growing industry is eager to explore alternative markets to maximize financial returns. Identifying suitable processing strategies and high-value products that suit young, plantation-grown hardwoods have proven challenging; however, recent veneer processing trials using simple veneer technology have demonstrated more acceptable recoveries of marketable products. The recovered veneers have visual qualities that are suitable for structurally-based products; however, the mechanical properties of the veneer are largely unknown. Veneers resulting from processing trials of six commercially important Australian hardwood species were used to determine key wood properties (i.e., density, dynamic modulus of elasticity (MoE, and specific MoE. The study revealed that a wide variation of properties existed between species and also within species. Simple mathematical modeling, using sigmoidal curves, was demonstrated to be an effective method to model the evolution of key wood properties across the billet radius and along the resulting veneer ribbon with benefits for tree breeders and processors.

  3. Defining Hardwood Veneer Log Quality Attributes

    Science.gov (United States)

    Jan Wiedenbeck; Michael Wiemann; Delton Alderman; John Baumgras; William Luppold

    2004-01-01

    This publication provides a broad spectrum of information on the hardwood veneer industry in North America. Veneer manufacturers and their customers impose guidelines in specifying wood quality attributes that are very discriminating but poorly defined (e.g., exceptional color, texture, and/or figure characteristics). To better understand and begin to define the most...

  4. Thermoelectric properties of I-doped n-type Bi2Te3-based material prepared by hydrothermal and subsequent hot pressing

    Directory of Open Access Journals (Sweden)

    Fang Wu

    2017-04-01

    Full Text Available I-doped Bi2Te3−xIx (x=0, 0.05, 0.1, 0.2 flower-like nanoparticles were synthesized by a hydrothermal method through a careful adjustment of the amount of ethylenediamine tetraacetic acid surfactant. The nanopowders of flower-like nanoparticles were hot-pressed into bulk pellets and the thermoelectric properties of the pellets were investigated. The results showed that I-doping decreased the electrical resistivity effectively, and the thermal conductivitives of the Bi2Te3−xIx bulk samples was lower because of the closer atomic mass of I compared to Te. As a result, a ZT value of 1.1 was attained at 448 K for the Bi2Te2.9I0.1 sample.

  5. Development of Duplex Stainless Steels by Field-Assisted Hot Pressing: Influence of the Particle Size and Morphology of the Powders on the Final Mechanical Properties

    Science.gov (United States)

    García-Junceda, A.; Rincón, M.; Torralba, J. M.

    2018-01-01

    The feasibility of processing duplex stainless steels with promising properties using a powder metallurgical route, including the consolidation by field-assisted hot pressing, is assessed in this investigation. The influence of the particle size and morphology of the raw austenitic and ferritic powders on the final microstructure and properties is also evaluated for an austenitic content of 60 wt pct. In addition, the properties of a new microconstituent generated between the initial constituents are analyzed. The maximum sintered density (98.9 pct) and the best mechanical behavior, in terms of elastic modulus, nanohardness, yield strength, ultimate tensile strength, and ductility, are reached by the duplex stainless steel processed with austenitic and ferritic gas atomized stainless steel powders.

  6. Fabrication and Analysis of the Wear Properties of Hot-Pressed Al-Si/SiCp + Al-Si-Cu-Mg Metal Matrix Composite

    Science.gov (United States)

    Bang, Jeongil; Oak, Jeong-Jung; Park, Yong Ho

    2016-01-01

    The aim of this study was to characterize microstructures and mechanical properties of aluminum metal matrix composites (MMC's) prepared by powder metallurgy method. Consolidation of mixed powder with gas atomized Al-Si/SiCp powder and Al-14Si-2.5Cu-0.5Mg powder by hot pressing was classified according to sintering temperature and sintering time. Sintering condition was optimized using tensile properties of sintered specimens. Ultimate tensile strength of the optimized sintered specimen was 228 MPa with an elongation of 5.3% in longitudinal direction. In addition, wear properties and behaviors of the sintered aluminum-based MMC's were analyzed in accordance with vertical load and linear speed. As the linear speed and vertical load of the wear increased, change of the wear behavior occurred in order of oxidation of Al-Si matrix, formation of C-rich layer, Fe-alloying to matrix, and melting of the specimen

  7. Effects of internal gas pressure and microstructure on the mechanisms of hot-pressing and swelling in ceramics. Final report, June 1, 1979-May 31, 1980

    International Nuclear Information System (INIS)

    Solomon, A.A.

    1980-08-01

    The results of the study of the effects of internal and external gas pressures on ceramics are summarized. The new experimental systems for studying these phenomena are described. The study has shown that the rate of volume change in ZnO is linearly related to the total pressure driving force. Swelling and hot-pressing can be described on a consistent basis in terms of this driving force. For ZnO, Ni and UO 2 the rate of volume change is dependent on bulk diffusion. The porosity evolution during swelling is described and the resintering phenomenon is identified. Various models for pore growth and shrinkage are considered and related to the behavior of the different systems

  8. Effects of internal gas pressure and microstructure on the mechanisms of hot-pressing and swelling in ceramics. Progress report, June 1, 1975--March 31, 1976

    International Nuclear Information System (INIS)

    Solomon, A.A.

    1976-02-01

    Pressurization system components for studying the hot-pressing and swelling behavior of CoO were built. A vacuum furnace was modified so that dimensional changes can be continuously monitored during sintering under high vacuum. Chracterization of the CoO starting powders was initiated. A technique was developed to form geometrically uniform pellet compacts of high green density using low pressure punch and die pressing followed by high pressure isostatic compaction to obtain uniform green density. Preliminary sintering experiments were carried out at 1 atm in air, inert gas, and under vacuum with specimen deflection continuously monitored. Resulting microstructures were characterized using mercury porosimetry and quantitative optical microscopy. Drastic differences in sintering rates in vacuum and air were observed

  9. Effect of pressing temperature on the wear resistance of a Co-based Cr-Mo powder alloy produced by hot pressing

    Energy Technology Data Exchange (ETDEWEB)

    Somunkiran, Ilyas [Firat Univ., Elazig (Turkey). Metallurgical and Materials Engineering Dept.; Balin, Ahmet [Siirt Univ. (Turkey). Dept. of Vocational High School

    2016-02-01

    In this study, Co-based Cr-Mo powder alloy was produced at different pressing temperatures by using hot pressing technique and abrasive wear behaviors of the produced specimens were examined. Produced specimens were exposed to abrasive wear experiment using block on disc wear test device by applying a load of 50 N with 100-mesh SiC abrasive paper. Each specimen was investigated at 25, 50, 75 and 100 m. At the end of the experiment, abrasive wear results of the specimens were determined by calculating their mass losses. Microstructural properties of the specimens which were produced at different pressing temperatures were investigated by optical and SEM examinations and their wear resistances were examined by abrasive wear experiments. Consequently, it was observed that in Co-based Cr-Mo powder alloy produced by hot pressing technique; as sintering temperature increased, size of neck formations between the powder grains increased, porosity decreased and abrasive wear resistance increased. [German] In diesem Beitrag zugrunde liegenden Studie wurde eine Co-basierte Cr-Mo-Legierung mittels Heisspressens hergestellt und der Abrasivverschleisswiderstand dieser Proben untersucht. Die hergestellten Proben wurden dem Abrasivverschleissversuch durch einen Block-Scheibe-Versuchsaufbau unterzogen, wobei eine Kraft von 50 N mit einem SiC-Papier (100 mesh) verwendet wurde. Jede Probe wurde ueber eine Distanz von 25, 50, 75 und 100 m untersucht. Am Ende der jeweiligen Experimente wurden die Abrasivverschleissergebnisse ermittelt, indem die Massenverluste berechnet wurden. Die mikrostrukturellen Eigenschaften der Proben, die bei verschiedenen Presstemperaturen hergestellt wurden, wurden mittels optischer und Rasterelektronenmikroskopie bestimmt und ihr Verschleisswiderstand anhand der Verschleissversuche ermittelt. Schliesslich wurde beobachtet, dass bei steigender Sintertemperatur der heissgespressten Co-basierten Cr-Mo-Pulverlegierung die Groesse der Einschnuerungen zwischen den

  10. Flexural properties of laminated veneer lumber manufactured from ultrasonically rated red maple veneer : a pilot study.

    Science.gov (United States)

    Xiping Wang; Robert J. Ross; Brian K. Brashaw; Steven A. Verhey; John W. Forsman; John R. Erickson

    2003-01-01

    The study described in this report was conducted to examine the flexural properties of laminated veneer lumber (LVL) manufactured from red maple veneer. Ultrasonically rated veneer, which was peeled from low value red maple saw-logs, was fabricated into 1/2-in.-(1.3-cm-) and 2-in.-(5-cm-) thick LVL billets. The flexural properties of the billets and of corresponding...

  11. Preparation of alumina-chromium composites by reactive hot-pressing Al + Cr2O3 based powders

    International Nuclear Information System (INIS)

    Osso, D.; Mocellin, A.; Caer, G. le; Pianelli, A.

    1993-01-01

    Chromium-Alumina based composites have been obtained by reactive sintering under load and vacuum of various powder blends. The starting mixtures have been prepared from commercially available aluminium metal, chromium and aluminium oxides, and a thermally unstable titanium compound respectively. Differential thermal analysis (DTA) and differential calorimetry (DSC) as well as X-ray diffraction were used to identify chemical transformations taking place within the system. Microstructure changes were observed via scanning electron microscopy (SEM) with an energy dispersive spectroscopy system (EDS). Chemical reactions in relevant binary subsystems have been investigated qualitatively in order to understand the course of events in the more complex quaternary mixtures. The possibilities of forming intermetallic phases in both the Al-Ti and Cr-Ti systems and of dissolving some Cr 2 O 3 into the product Al 2 O 3 phase have been considered. The influence of such parameters as thermal schedule and initial aluminium content on those side reactions and the resulting microstructures was investigated. (orig.)

  12. Veneers

    Science.gov (United States)

    ... in many situations. They provide a much more conservative approach to changing a tooth's color, size or ... See Flaws Home | InfoBites | Find a Dentist | Your Family's Oral Health | RSS About AGD | Contact AGD | Site ...

  13. The clinical microscope and direct composite veneer

    DEFF Research Database (Denmark)

    Pascotto, Renata C; Benetti, Ana Raquel

    2010-01-01

    This paper presents the advantages and limitations related to the use of a clinical microscope in restorative dentistry, and it demonstrates the aid of magnification during preparation and restoration of a direct composite veneer. Good illumination and visibility is important to adequately viewin...... the adjacent dental tissues so that the resin composite buildup can mimic natural teeth. The reproduction of details results in a naturally esthetic direct veneer....

  14. Thermoelectric properties of n-type Bi{sub 2}(Te{sub 1{minus}x}Se{sub x}){sub 3} fabricated by mechanical alloying and hot pressing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H J; Choi, J S; Oh, T S; Hyun, D B

    1997-07-01

    Thermoelectric properties of polycrystalline Bi{sub 2}(Te{sub 1{minus}x}Se{sub x}){sub 3} (0.05 {le} x {le} 0.25), fabricated by mechanical alloying and hot pressing, have been investigated. Formation of n-type Bi{sub 2}(Te{sub 0.9}Se{sub 0.1}){sub 3} alloy powders was completed by mechanical alloying for 3 hours at ball-to-material ratio of 5:1, and processing time for Bi{sub 2}(Te{sub 1{minus}x}Se{sub x}){sub 3} formation increased with Bi{sub 2}Se{sub 3} content x. Figure-of-merit of Bi{sub 2}(Te{sub 0.9}Se{sub 0.1}) was markedly increased by hot pressing at temperatures above 450 C, and maximum value of 1.9 x 10{sup {minus}3}/K was obtained by hot pressing at 550 C. With addition of 0.015 wt% Bi as acceptor dopant, figure-of-merit of Bi{sub 2}(Te{sub 0.9}Se{sub 0.1}){sub 3} was hot pressed at 550 C, could be improved to 2.1 x 10{sup {minus}3}/K. When Bi{sub 2}(Te{sub 1{minus}x}Se{sub x}){sub 3} was hot pressed at 550 C, figure-of-merit increased from 1.14 x 10{sup {minus}3}/K to 1.92 x 10{sup {minus}3}/K with increasing Bi{sub 2}Se{sub 3} content x from 0.05 to 0.15, and then decreased to 1.30 x 10{sup {minus}3}/K for x = 0.25 composition.

  15. Fabrication of a Nano-ZnO/Polyethylene/Wood-Fiber Composite with Enhanced Microwave Absorption and Photocatalytic Activity via a Facile Hot-Press Method

    Directory of Open Access Journals (Sweden)

    Baokang Dang

    2017-11-01

    Full Text Available A polyethylene/wood-fiber composite loaded with nano-ZnO was prepared by a facile hot-press method and was used for the photocatalytic degradation of organic compounds as well as for microwave absorption. ZnO nanoparticles with an average size of 29 nm and polyethylene (PE powders were dispersed on the wood fibers’ surface through a viscous cationic polyacrylamide (CPAM solution. The reflection loss (RL value of the resulting composite was −21 dB, with a thickness of 3.5 mm in the frequency of 17.17 GHz. The PE/ZnO/wood-fiber (PZW composite exhibited superior photocatalytic activity (84% methyl orange degradation within 300 min under UV light irradiation. ZnO nanoparticels (NPs increased the storage modulus of the PZW composite, and the damping factor was transferred to the higher temperature region. The PZW composite exhibited the maximum flexural strength of 58 MPa and a modulus of elasticity (MOE of 9625 MPa. Meanwhile, it also displayed dimensional stability (thickness swelling value of 9%.

  16. Influence of Fiber Content on Mechanical and Morphological Properties of Woven Kenaf Reinforced PVB Film Produced Using a Hot Press Technique

    Directory of Open Access Journals (Sweden)

    Suhad D. Salman

    2016-01-01

    Full Text Available This work addresses the results of experimental investigation carried out on mechanical and morphological properties of plain woven kenaf fiber reinforced PVB film which was prepared by hot press technique. The composites were prepared with various fiber contents: 0%, 10%, 20%, 30%, 40%, 50%, and 60% (by weight, with the processing parameters 165°C, 20 min, and at a pressure of 8 MPa applied on the material. Tensile, flexural, and Charpy impact properties were studied as well as morphological properties of impact fracture surface. With the increase in kenaf fibers content up to 40%, the PVB composites have shown lower tensile and flexural strength accompanied with reduction in the ultimate strain of the composite. The results showed that impact properties were affected in markedly different ways by using various kenaf contents and decrease with the increase in kenaf fiber content up to 40%; however, high impact strength was observed even with 40% kenaf fiber content. Furthermore, scanning electron microscopy for impact samples was utilised to demonstrate the different failures in the fracture surfaces for various kenaf fibers contents.

  17. Microstructure and Mechanical Properties of Multiphase Strengthened Al/Si/Al_2O_3/SiO_2/MWCNTs Nano composites Sintered by In Situ Vacuum Hot Pressing

    International Nuclear Information System (INIS)

    Li, J.; Jiang, X.; Zhu, D.; Zhu, M.; Shao, Z.; Johnson, S.; Luo, Z.

    2015-01-01

    Eutectic Al/Si binary alloy is technically one of the most important Al casting alloys due to its high corrosion resistance, evident shrinkage reduction, low thermal expansion coefficient, high fluidity, and good weldability. In this work, multi phased Al/Si matrix nano composites reinforced with Al_2O_3 and multi walled carbon nano tubes (MWCNTs) have been sintered by an in situ vacuum hot-pressing method. The alumina Al_2O_3 nanoparticles were introduced by an in situ reaction of Al with SiO_2. Microstructure and mechanical properties of the sintered Al/Si/Al_2O_3/SiO_2/MWCNTs nano composites with different alumina contents were investigated. The mechanical properties were determined by micro-Vickers hardness and compressive and shear strength tests. The results demonstrated that in situ alumina and MWCNTs had impacts on microstructure and mechanical properties of the nano composites. Based on the mechanical properties and microstructure of the nano composites, strengthening and fracture mechanisms by multiple reinforcements were analyzed

  18. Fabrication of Hadfield-Cored Multi-layer Steel Sheet by Roll-Bonding with 1.8-GPa-Strength-Grade Hot-Press-Forming Steel

    Science.gov (United States)

    Chin, Kwang-Geun; Kang, Chung-Yun; Park, Jaeyeong; Lee, Sunghak

    2018-05-01

    An austenitic Hadfield steel was roll-bonded with a 1.8-GPa-strength-grade martensitic hot-press-forming (HPF) steel to fabricate a multi-layer steel (MLS) sheet. Near the Hadfield/HPF interface, the carburized and decarburized layers were formed by the carbon diffusion from the Hadfield (1.2%C) to HPF (0.35%C) layers, and could be regarded as kinds of very thin multi-layers of 35 μm in thickness. The tensile test and fractographic data indicated that the MLS sheet was fractured abruptly within the elastic range by the intergranular fracture occurred in the carburized layer. This was because C was mainly segregated at prior austenite grain boundaries in the carburized layer, which weakened grain boundaries to induce the intergranular fracture. In order to solve the intergranular facture problem, the MLS sheet was tempered at 200 °C. The stress-strain curve of the tempered MLS sheet lay between those of the HPF and Hadfield sheets, and a rule of mixtures was roughly satisfied. Tensile properties of the MLS sheet were dramatically improved after the tempering, and the intergranular fracture was erased completely. In particular, the yield strength up to 1073 MPa along with the high strain hardening and excellent ductility of 32.4% were outstanding because the yield strength over 1 GPa was hardly achieved in conventional austenitic steels.

  19. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers.

    Science.gov (United States)

    Mahmood, Deyar Jallal Hadi; Linderoth, Ewa H; Wennerberg, Ann; Vult Von Steyern, Per

    2016-01-01

    To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) fixed dental prostheses (FDPs) with respect to the choice of core material, veneering material area, manufacturing technique, design of connectors, and radii of curvature of FDP cores. A total of 110 three-unit Y-TZP FDP cores with one intermediate pontic were made. The FDP cores in groups 1-7 were made with a split-file design, veneered with manually built-up porcelain, computer-aided design-on veneers, and over-pressed veneers. Groups 8-11 consisted of FDPs with a state-of-the-art design, veneered with manually built-up porcelain. All the FDP cores were subjected to simulated aging and finally loaded to fracture. There was a significant difference (Pdesigns, but not between the different types of Y-TZP materials. The split-file designs with VITABLOCS(®) (1,806±165 N) and e.max(®) ZirPress (1,854±115 N) and the state-of-the-art design with VITA VM(®) 9 (1,849±150 N) demonstrated the highest mean fracture values. The shape of a split-file designed all-ceramic reconstruction calls for a different dimension protocol, compared to traditionally shaped ones, as the split-file design leads to sharp approximal indentations acting as fractural impressions, thus decreasing the overall strength. The design of a framework is a crucial factor for the load bearing capacity of an all-ceramic FDP. The state-of-the-art design is preferable since the split-file designed cores call for a cross-sectional connector area at least 42% larger, to have the same load bearing capacity as the state-of-the-art designed cores. All veneering materials and techniques tested in the study, split-file, over-press, built-up porcelains, and glass-ceramics are, with a great safety margin, sufficient for clinical use both anteriorly and posteriorly. Analysis of the fracture pattern shows

  20. Transformation plasticity and hot pressing

    International Nuclear Information System (INIS)

    Chaklader, A.C.D.

    1975-01-01

    The transformation plasticity during the phase transition of quartz to cristobalite, monoclinic reversible tetragonal of zirconia, metakaolin to a spinel phase, and brucite to periclase was investigated by studying their compaction characteristics. Viscous flow was found to be the predominant mechanism of mass transport (after an initial particle rearrangement stage) in the case of quartz to cristobalite phase change where the transformation was associated with the formation of an intermediate amorphous silica phase. The results on the monoclinic reversible tetragonal transformation of zirconia indicated that it is most likely controlled by internal strain induced by the stress associated with the volume change (ΔV/V) and the flow stress of the weaker phase. Particle movement and deformation of the weaker phase (possibly tetragonal) may be the manifestation of this plasticity. The plasticity in the case of metakaolin to a spinel phase appeared to start before the exothermic reaction (generally encountered in a dta plot) and may be diffusion controlled. The plasticity encountered during brucite to periclase transformation may be the combined effect of disintegration of precursor particles, vapor-phase lubrication and some deformability of freshly formed very fine MgO particles

  1. Hot pressing of U-UC cermets and stoichiometric uranium monocarbide; Preparation par frittage sous charge de cermets U-UC et de monocarbure stoechiometrique

    Energy Technology Data Exchange (ETDEWEB)

    Dubuisson, J; Houyvet, A; Le Boulbin, E; Lucas, R; Moranville, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    High density fuels, either in uranium monocarbide or in U-UC cermets have been prepared on laboratory-scale, by hot pressing of mixtures of uranium powder and graphite in suitable proportions. Uranium powder is prepared by calcium reduction of UO{sub 2} followed by an acetic leaching at low temperature. An adequate protection-treatment permits the manipulation of the powder in the open air. Uranium and Graphite powders are intimately mixed and then hot pressed in a double effect graphite die at a temperature of 900-1000 deg. C under a charge of 200 kg/cm{sup 2} during 3 hours. A special design of the die avoids the breaking of the graphite during the sintering. In this way, samples are prepared, the characteristics of which are: 1) {+-} 5 pour cent of homogeneity for a ratio height/diameter = 2. 2) almost theoretical density (98 pour cent) 3) low concentration of unreacted carbon (heat treatment of stoichiometric monocarbide can be useful for completion of reaction) 4) the micrographic examination shows: - a network of monocarbide surrounding uranium in the case of low concentration cermets (<2,5 per cent C) - two networks intimately mixed for high concentration cermets (<2,5 per cent C) - a fine grain structure for the monocarbide (10 u). 5) In every case, the X rays examinations show a fine grain structure without any orientation, and no UC{sub 2}. Some indications are given on the physical (thermal cycling, conductibility) and chemical properties (corrosion, reaction with cladding materials). (author)Fren. [French] Une methode de preparation de combustibles de haute densite, soit en monocarbure d'uranium, soit en cermets U-UC, a ete mise au point au laboratoire. Il s'agit du frittage sous charge de melanges de poudres d'uranium et de graphite en proportion convenable. La poudre d'uranium est elaboree par calciothermie de l'oxyde UO{sub 2} suivie d'un lavage acetique a basse temperature. Un traitement de protection adequat pe sa manipulation a l'air. Les poudres

  2. On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process.

    Science.gov (United States)

    Ahmad, Azlan; Lajis, Mohd Amri; Yusuf, Nur Kamilah

    2017-09-19

    Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.

  3. On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR Prepared Using Hot Press Forging (HPF Process

    Directory of Open Access Journals (Sweden)

    Azlan Ahmad

    2017-09-01

    Full Text Available Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.

  4. Three-Point Bending Tests of Zirconia Core/Veneer Ceramics for Dental Restorations

    Directory of Open Access Journals (Sweden)

    Massimo Marrelli

    2013-01-01

    Full Text Available Introduction. The mechanical strength and the surface hardness of commercially available yttrium-doped zirconia were investigated. Furthermore, a comparative study of eight different ceramic veneers, to be used for the production of two-layered all-ceramic restorative systems, was carried out. Materials and Methods. Four types of zirconia specimens were analyzed, according to a standard ISO procedure (ISO 6872. Besides, two-layered zirconia-veneer specimens were prepared for three-point bending tests. Results. A strong effect of the surface roughness on the mechanical strength of zirconia specimens was observed. Finally, a comparative study of eight commercially available veneering ceramics shows different modes of failure between the selected veneers. Conclusion. The results indicate that close attention should be paid to the preparation of zirconia-based crowns and bridges by CAD/CAM process, because surface roughness has an important effect on the mechanical strength of the material. Finally, the results of the mechanical tests on two-layered specimens represent an important support to the choice of the veneering ceramic.

  5. Influence of veneer thickness on residual stress profile in veneering ceramic: measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2012-02-01

    The veneering process of frameworks induces residual stresses and can initiate cracks when combined with functional stresses. The stress distribution within the veneering ceramic as a function of depth is a key factor influencing failure by chipping. This is a well-known problem with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objective of this study is to investigate the influence of veneer thickness on the stress profile in zirconia- and metal-based structures. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. The stress profile was measured in bilayered disc samples of 20 mm diameter, with a 1 mm thick zirconia or metal framework. Different veneering ceramic thicknesses were performed: 1 mm, 1.5 mm, 2 mm, 2.5 mm and 3 mm. All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth up to 0.5-1.0 mm from the surface, and then becoming compressive again near the framework, except for the 1.5 mm-veneered zirconia samples which exhibited interior tensile stresses. Stresses in the surface of metal samples were not influenced by veneer thickness. Variation of interior stresses at 1.2 mm from the surface in function of veneer thickness was inverted for metal and zirconia samples. Veneer thickness influences in an opposite way the residual stress profile in metal- and in zirconia-based structures. A three-step approach and the hypothesis of the crystalline transformation are discussed to explain the less favorable residual stress development in zirconia samples. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Influence of core design, production technique, and material selection on fracture behavior of yttria-stabilized tetragonal zirconia polycrystal fixed dental prostheses produced using different multilayer techniques: split-file, over-pressing, and manually built-up veneers

    Directory of Open Access Journals (Sweden)

    Mahmood DJH

    2016-02-01

    Full Text Available Deyar Jallal Hadi Mahmood, Ewa H Linderoth, Ann Wennerberg, Per Vult Von Steyern Department of Prosthetic Dentistry, Faculty of Odontology, Malmö University, Malmö, Sweden Aim: To investigate and compare the fracture strength and fracture mode in eleven groups of currently, the most commonly used multilayer three-unit all-ceramic yttria-stabilized tetragonal zirconia polycrystal (Y-TZP fixed dental prostheses (FDPs with respect to the choice of core material, veneering material area, manufacturing technique, design of connectors, and radii of curvature of FDP cores. Materials and methods: A total of 110 three-unit Y-TZP FDP cores with one intermediate pontic were made. The FDP cores in groups 1–7 were made with a split-file design, veneered with manually built-up porcelain, computer-aided design-on veneers, and over-pressed veneers. Groups 8–11 consisted of FDPs with a state-of-the-art design, veneered with manually built-up porcelain. All the FDP cores were subjected to simulated aging and finally loaded to fracture. Results: There was a significant difference (P<0.05 between the core designs, but not between the different types of Y-TZP materials. The split-file designs with VITABLOCS® (1,806±165 N and e.max® ZirPress (1,854±115 N and the state-of-the-art design with VITA VM® 9 (1,849±150 N demonstrated the highest mean fracture values. Conclusion: The shape of a split-file designed all-ceramic reconstruction calls for a different dimension protocol, compared to traditionally shaped ones, as the split-file design leads to sharp approximal indentations acting as fractural impressions, thus decreasing the overall strength. The design of a framework is a crucial factor for the load bearing capacity of an all-ceramic FDP. The state-of-the-art design is preferable since the split-file designed cores call for a cross-sectional connector area at least 42% larger, to have the same load bearing capacity as the state-of-the-art designed

  7. Effect of core/veneer thickness ratio and veneer translucency on absolute and relative translucency of CAD-On restorations

    Directory of Open Access Journals (Sweden)

    Mennatallah Mohie el-Din Wahba, (BDS, MSc

    2017-06-01

    Conclusions: Only veneer translucency had significant effect over contrast ratio values, while on the other hand, absolute translucency values were significantly affected by the core/veneer thickness ratio, veneer translucency and interaction between them. It was clear that absolute translucency measurements showed higher translucency values for the restorations than contrast ratio measurements.

  8. Interfacial Adhesion and Damping Characteristics of Laminated Veneer Lumber Intercalated with Rubber Sheets

    Directory of Open Access Journals (Sweden)

    Jingquan Han

    2016-06-01

    Full Text Available Laminated wood veneer lumber intercalated with rubber sheets (LLVR was fabricated using a layered adhesive system composed of polyaryl polymethylene isocyanate (PAPI for wood-rubber inter-bonding and phenol formaldehyde (PF resin to glue the wood veneers. The optimized manufacturing process (chloroprene rubber: CR; PAPI: 80 g/m2; PF: 200 g/m2; and silane: 9.0 wt.% was determined. The process as developed was then utilized to fabricate nine-ply LLVRs of five balanced constructions with two or three CR laminates used as various layers. The physico-mechanical properties of the LLVRs were evaluated, and the results showed that LLVRs had strong shear strength, sound dimensional stability, decent bending strength, and favorable toughening and buffering performances. The newly developed product is an interesting potential alternative to traditional laminated veneer lumber or plywood.

  9. 利用响应面法研究微孔处理杨木单板的胶合性能%Bonding Properties of Poplar Veneer Punched with Micro-holes by Response Surface Methodology

    Institute of Scientific and Technical Information of China (English)

    唐忠荣; 黄健; 戴玉玲; 丰江拓

    2015-01-01

    利用响应面法分析研究了经微孔处理后的杨木单板的胶合性能。通过对杨木单板进行微孔处理,可使胶黏剂通过微孔渗入单板体内,增加杨木单板的本体强度,同时也可使相邻胶层透过微孔形成一体而增加单板的胶合强度等,以期制造出一种高性能的地板基材。结果表明:在试验范围内,随微孔孔径增大,孔距减小和施胶量的增加,其胶合强度增加;随热压压力增加,胶合强度先增强,当压力超过0.8 MPa,胶合强度反而降低。%We studied the bonding properties of poplar veneer punched with micro-holes by using response surface experiment. The permeability of poplar veneer increased after micro-hole punching.The adhesive could penetrate into the veneer through these micro holes, and the poplar veneer was strengthened.Through micro holes, the neighboring glue lines formed a whole to increase the bonding strength of veneers.Expecting to produce a high performance floor material.The bonding strength of poplar plywood increased with the increasing of micro-hole diameter,resin content , and the decreasing of holes distance.With the increasing of hot pressing pressure, the bonding strength was improved firstly, however, it declined when the pressure exceeded 0.8 MPa.

  10. [Veneer computer aided design based on reverse engineering technology].

    Science.gov (United States)

    Liu, Ming-li; Chen, Xiao-dong; Wang, Yong

    2012-03-01

    To explore the computer aided design (CAD) method of veneer restoration, and to assess if the solution can help prosthesis meet morphology esthetics standard. A volunteer's upper right central incisor needed to be restored with veneer. Super hard stone models of patient's dentition (before and after tooth preparation) were scanned with the three-dimensional laser scanner. The veneer margin was designed as butt-to-butt type. The veneer was constructed using reverse engineering (RE) software. The technique guideline of veneers CAD was explore based on RE software, and the veneers was smooth, continuous and symmetrical, which met esthetics construction needs. It was a feasible method to reconstruct veneer restoration based on RE technology.

  11. Estimating the spread rate of urea formaldehyde adhesive on birch (Betula pendula Roth) veneer using fluorescence

    Science.gov (United States)

    Toni Antikainen; Anti Rohumaa; Christopher G. Hunt; Mari Levirinne; Mark Hughes

    2015-01-01

    In plywood production, human operators find it difficult to precisely monitor the spread rate of adhesive in real-time. In this study, macroscopic fluorescence was used to estimate spread rate (SR) of urea formaldehyde adhesive on birch (Betula pendula Roth) veneer. This method could be an option when developing automated real-time SR measurement for...

  12. Digital workflow for virtually designing and milling ceramic lithium disilicate veneers: a clinical report.

    Science.gov (United States)

    Zandinejad, A; Lin, W S; Atarodi, M; Abdel-Azim, T; Metz, M J; Morton, D

    2015-01-01

    Laminate veneers have been routinely used to restore and enhance the appearance of natural dentition. The traditional pathway for fabricating veneers consisted of making conventional polyvinyl siloxane impressions, producing stone casts, and fabricating final porcelain prostheses on stone dies. Pressed ceramics have successfully been used for laminate veneer fabrication for several years. Recently, digital computer-aided design/computer-aided manufacturing scanning has become commercially available to make a digital impression that is sent electronically to a dental laboratory or a chairside milling machine. However, technology has been developed to allow digital data acquisition in conjunction with electronically transmitted data that enables virtual design of restorations and milling at a remote production center. Following the aforementioned workflow will provide the opportunity to fabricate a physical cast-free restoration. This new technique has been reported recently for all-ceramic IPS e.max full-coverage pressed-ceramic restorations. However, laminate veneers are very delicate and technique-sensitive restorations when compared with all-ceramic full-coverage ones made from the same material. Complete digital design and fabrication of multiple consecutive laminate veneers seems to be very challenging. This clinical report presents the digital workflow for the virtual design and fabrication of multiple laminate veneers in a patient for enhancing the esthetics of his maxillary anterior teeth. A step-by-step process is presented with a discussion of the advantages and disadvantages of this novel technique. Additionally, the use of lithium disilicate ceramic as the material of choice and the rationale for such a decision is discussed.

  13. An indirect veneer technique for simple and esthetic treatment of anterior hypoplastic teeth

    Directory of Open Access Journals (Sweden)

    Amit Khatri

    2010-01-01

    Full Text Available This study describes a technique for treating anterior hypoplastic teeth using indirect nanocomposite veneer restoration. The prime advantage of an indirect veneer technique is that it provides an esthetic and conservative result. One of the most frequent reasons that patients seek dental care is discolored anterior teeth. Although treatment options such as removal of surface stains, bleaching, microabrasion or macroabrasion, veneering, and placement of porcelain crowns are available, conservative approach such as veneer preserves the natural tooth as much as possible. Full veneers are recommended for the restoration of localized defects or areas of intrinsic discoloration, which are caused by deeper internal stains or enamel defects. Indirectly fabricated veneers are much less sensitive compared to a operator′s technique and if multiple teeth are to be veneered, indirect veneers can be usually placed much more expeditiously. Indirect veneers last much longer than the direct veneers. Therefore, indirectly fabricated veneers are more advantageous than directly fabricated veneers in many cases.

  14. The microstructures and mechanical properties of Al-15Si-2.5Cu-0.5Mg/(wt%)B{sub 4}C composites produced through hot pressing technique and subjected to hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Ozer, Alpay, E-mail: alpiozer@gmail.com

    2016-11-01

    In this study, B{sub 4}C (5, 10, and 15 wt%) particle-reinforced Ecka Alumix 231{sup ®} aluminum matrix composites were produced through the hot pressing technique. Some of these samples were subjected to hot extrusion as a secondary treatment at 4:1 ratio at a temperature of 555 °C. The obtained samples were subjected to density measurement, hardness test, microstructure analysis, and three-point bending test, and their fracture surfaces were examined. A density of over 99% was found in the samples. Al-rich solid solution and primary Si, CuAl{sub 2}, Al{sub 2}CuMg, and Mg{sub 2}Si phases in the microstructure were determined through X-ray diffraction analysis. Grain sizes were found to be 20 μm and 2 μm in the microstructures of the samples produced through hot pressing technique and of those subjected to additional hot extrusion, respectively. High hardness values were obtained in the samples subjected to hot extrusion. In these samples, wt% B{sub 4}C particle ratio and transverse rupture strength increased considerably. Furthermore, the highest compressive strain value was obtained in the 10 wt% B{sub 4}C particle-reinforced composites subjected to hot extrusion. - Highlights: • Liquid phase formed at the temperature of hot pressing and hot extrusion. • In the samples, over 99.19% density was obtained. • Average matrix grain size was measured to be 2 μm through hot extrusion. • As wt% B{sub 4}C ratio increased, transverse rupture strength values increased. • High compressive strain values were obtained in the hot extrusion samples.

  15. Additively Manufactured Titanium and Cobalt-Chromium Implant Frameworks: Fit and Effect of Ceramic Veneering.

    Science.gov (United States)

    Svanborg, Per; Eliasson, Alf; Stenport, Victoria

    The purpose of this study was to evaluate the fit of additively manufactured cobalt-chromium and titanium and CNC-milled titanium frameworks before and after ceramic veneering. Ten stone casts simulating an edentulous maxilla provided with six abutment analogs were produced. For each stone cast, one additively manufactured cobalt-chromium framework (AM CoCr) and one titanium framework (AM Ti) were fabricated. The fit was analyzed with a coordinate measuring machine in three dimensions (x, y, and z axes) using best-fit virtual matching of center point coordinates, before and after ceramic veneering. CNC-milled titanium frameworks (CNC Ti) and earlier results from CNC-milled cobalt-chromium frameworks (CNC CoCr) were used for comparison. All frameworks presented minor misfit before and after veneering in the horizontal plane (x- and y-axes) between 2.9 and 13.5 μm and in the vertical plane (z-axis) between 1.6 and 5.4 μm. Ceramic veneering affected the fit of all groups of frameworks. Both AM Ti and AM CoCr presented significantly smaller distortion in the vertical plane compared with the CNC-milled frameworks. Implant-supported frameworks can be produced in either Ti or CoCr using either CNC milling or additive manufacturing with a fit well within the range of 20 μm in the horizontal plane and 10 μm in the vertical plane. The fit of frameworks of both materials and production techniques are affected by the ceramic veneering procedure to a small extent.

  16. Yield and ultrasonic modulus of elasticity of red maple veneer

    Science.gov (United States)

    Robert J. Ross; Steven Verhey; John R. Erickson; John W. Forsman; Brian K. Brashaw; Crystal L. Pilon; Xiping Wang

    2004-01-01

    The purpose of the study was to assess the potential for using red maple sawlogs to manufacture laminated veneer lumber (LVL). The primary objective was to determine the yield of ultrasonically graded veneer from red maple logs. A sample of 48 logs was obtained from six Eastern and Lake States in the United States. The logs were visually graded and shipped to a plywood...

  17. Relationship between stress wave velocities of green and dry veneer

    Science.gov (United States)

    Brian K. Brashaw; Xiping Wang; Robert J. Ross; Roy F. Pellerin

    2004-01-01

    This paper evaluates the relationship between the stress wave velocities of green and dry southern pine and Douglas-fir veneers. A commercial stress wave timer and a laboratory signal analysis system were used to measure the transit time required for an induced stress wave to travel the longitudinal length of each veneer. Stress wave transit times were measured in the...

  18. Al_2O_3/PVdF-HFP-CMC/PE separator prepared using aqueous slurry and post-hot-pressing method for polymer lithium-ion batteries with enhanced safety

    International Nuclear Information System (INIS)

    Deng, Yaoming; Song, Xiaona; Ma, Zhen; Zhang, Xinhe; Shu, Dong; Nan, Junmin

    2016-01-01

    A composite separator is prepared to improve the safety of lithium ion batteries (LIBs) based on a gravure coating aqueous slurry and post-hot-pressing method. An environmentally friendly aqueous slurry with an Al_2O_3 ceramic holder and polyvinylidene difluoride-hexafluoropropylene (PVdF-HFP) and carboxymethyl cellulose (CMC) dual-binders is coated on a polyolefin (PE) substrate to form a prototype Al-PHC/PE separator. Then, after assembling the separator in the batteries and hot-pressing at 70 °C and 0.8 MPa for 3 h, the granular PVdF-HFP is transformed into a colloidal structure containing an electrolyte, which can binds the Al_2O_3 nanoparticles together and increases the battery hardness. Compared with a PE separator (9 μm), the Al-PHC/PE-2 separator (12 μm, with a Al_2O_3/PVdF-HFP weight ratio of 7/3) displays a comparative ionic conductivity of 9.3 × 10"−"4 S cm"−"2 and exhibits no obvious thermal deformation at 110 °C for 60 min. All of the batteries assembled with Al-PHC/PE-2 separators passed nail penetration and impact tests. In addition, the capacity retention increases from 83.4% to 87.6% when the battery is assembled with Al-PHC/PE-2 instead of a PE separator and charge-discharged at 0.7C/1.0C for 350 cycles. The enhanced safety and cycle performance indicate the promising prospect of Al-PHC/PE separators in LIBs.

  19. Advances in dental veneers: materials, applications, and techniques.

    Science.gov (United States)

    Pini, Núbia Pavesi; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite; Lovadino, José Roberto; Terada, Raquel Sano Suga; Pascotto, Renata Corrêa

    2012-01-01

    Laminate veneers are a conservative treatment of unaesthetic anterior teeth. The continued development of dental ceramics offers clinicians many options for creating highly aesthetic and functional porcelain veneers. This evolution of materials, ceramics, and adhesive systems permits improvement of the aesthetic of the smile and the self-esteem of the patient. Clinicians should understand the latest ceramic materials in order to be able to recommend them and their applications and techniques, and to ensure the success of the clinical case. The current literature was reviewed to search for the most important parameters determining the long-term success, correct application, and clinical limitations of porcelain veneers.

  20. Evaluation of the retentive means, opacifiers and veneering materials for veneered crowns using 137 Cs

    International Nuclear Information System (INIS)

    Nour, A.M.; El-Sadeek; M.E.; Ramadan, F.A.; Eskander, M.

    1991-01-01

    The purpose of this investigation is to evaluate the best plastic veneering material, which affords initial sealing and adaptation to the metal backing. Cs chloride is used for this purpose. The effect of different retentive means, namely, under cuts, wire loops, stainless steel grills, and acrylic beads, as well as the effect of different opaquers were studied. The influence of time factor and changing temperature was considered as well. The results obtained showed the following: 1- A quantitative method for the evaluation of micro leakage is essential parallel to the semiquantitative one. 2- The tested opaquer exhibits a better sealing ability. 3- The leakage increases significantly by temperature cycling, and by time duration with all the veneering materials tested. Composite is the least leak-sensitive material to changes in temperature. 4- Beads offered the best means of retention, to obtain the best sealing qualities.1 tab., 2 fig

  1. Damage Maps of Veneered Zirconia under Simulated Mastication

    Science.gov (United States)

    Kim, Jae-Won; Kim, Joo-Hyung; Janal, Malvin N.; Zhang, Yu

    2016-01-01

    Zirconia based restorations often fracture from chipping and/or delamination of the porcelain veneers. We hypothesize that veneer chipping/delamination is a result of the propagation of near-contact induced partial cone cracks on the occlusal surface under mastication. Masticatory loading involves the opposing tooth sliding along the cuspal inner incline surface with an applied biting force. To test this hypothesis, flat porcelain veneered zirconia plates were cemented to dental composites and cyclically loaded (contact–slide–liftoff) at an inclination angle as a simplified model of zirconia based restorations under occlusion. In the light of in-situ observation of damage evolution in a transparent glass/zirconia/polycarbonate trilayer, postmortem damage evaluation of porcelain/zirconia/composite trilayers using a sectioning technique revealed that deep penetrating occlusal surface partial cone fracture is the predominant fracture mode of porcelain veneers. Clinical relevance is discussed. PMID:19029080

  2. Straight studs from southern pine veneer cores and cordwood

    Science.gov (United States)

    Peter Koch

    1968-01-01

    An economically feasible system has been developed for converting southern pine veneer cores into straight 8-foot studs (2). Prototype studs - two per core - were 100 percent SPIB stud grade and better.

  3. Six-year follow-up with Empress veneers.

    Science.gov (United States)

    Fradeani, M

    1998-06-01

    This study reports on 6 years experience with IPS Empress laminate veneers. A total of 83 anterior veneers were positioned in 21 patients from January 1991 to December 1996 in the author's private practice. Final evaluation was carried out in May and June 1997. Color match, marginal discoloration, recurrent caries, contour, and marginal integrity were evaluated using the modified U.S. Public Health Service criteria at baseline and subsequent recall appointments. On the basis of the criteria used, a large percentage of veneers were rated Alfa. Only one failure was recorded, resulting in a success rate of 98.8%. A thorough description of clinical procedures and laboratory techniques through which anterior teeth can be successfully treated with ceramic veneers is supplied. A clinical case is presented to demonstrate the satisfactory esthetic results obtained using this very conservative restorative technique.

  4. The influence of fire retardants on the properties of beech and poplar veneers and plywood

    Directory of Open Access Journals (Sweden)

    Miljković Jovan

    2005-01-01

    Full Text Available Rising demands for fire resistance properties of wood construction and elements matching new standards have been an important part of building codes during the last decade. On the other side, lack of more detailed research on interaction between wood species and selected fire retardant chemicals even with basically one is evident. This is particularly truth with domestic wood species. In this research, beech and poplar veneers were immersed in 25% solutions of monoammonium phosphate (MP and sodium acetate (SA and impregnated for different periods of time. To determine the preliminary level of fire retardancy achieved in veneers before manufacturing of finished plywood, thermo gravimetric (TG and derivative thermo gravimetric (DTG methods were used. TG and DTG analyses of treated and untreated wood, as well as of fire retardants alone, were performed. The next properties of impregnated and no impregnated veneers and plywood were determined: absorption of imp regnant solution (A, weight percent gain (WPG of imp regnant, equilibrium moisture content (EMC, pH values, and in the case of plywood, strength and fire resistance. Fire resistance of plywood was tested in accordance with standard test for resistance to the effects of fire and the most efficient fire retardant, monoammonium phosphate, had the same result as TG/DTG analyses, which pointed out the validity of TG methods in predicting fire resistance of future products.

  5. Residual stress measurement in veneering ceramic by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2011-05-01

    Mismatch in thermal expansion properties between veneering ceramic and metallic or high-strength ceramic cores can induce residual stresses and initiate cracks when combined with functional stresses. Knowledge of the stress distribution within the veneering ceramic is a key factor for understanding and predicting chipping failures, which are well-known problems with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objectives of this study are to develop a method for measuring the stress profile in veneering ceramics and to compare ceramic-fused-to-metal compounds to veneered Yttria-tetragonal-zirconia-polycrystal ceramic. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. Because of the high sensitivity needed in comparison with industrial applications, a high sensitivity electrical measurement chain was developed. All samples exhibited the same type of stress vs. depth profile, starting with compressive at the ceramic surface, decreasing with depth and becoming tensile at 0.5-1.0mm from the surface, and then becoming slightly compressive again. The zirconia samples exhibited a stress depth profile of larger magnitude. The hole drilling method was shown be a practical tool for measuring residual stresses in veneering ceramics. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Immobilization of high activity nuclear wastes in sintered glass. Fabrication of blocks at semi-industrial scale by hot pressing technique

    International Nuclear Information System (INIS)

    Russo, D.O.; Messi, N.B.; Riquelme, R.; Sterba, M.E.; Audero, M.A.

    1990-01-01

    The sintering process under glass pressure has been studied as an alternative of melting with the aim of obtaining a monolytic material apt to preserve the high activity nuclear wastes. Different properties of the products obtained have been evaluated where the material is selected on the basis of the results attained. The purpose of this work is the equipment development and the process adjusting for the blocks obtainment. (Author) [es

  7. Simplified treatment of severe dental erosion with ultrathin CAD-CAM composite occlusal veneers and anterior bilaminar veneers.

    Science.gov (United States)

    Schlichting, Luís Henrique; Resende, Tayane Holz; Reis, Kátia Rodrigues; Magne, Pascal

    2016-10-01

    Restorative treatment for patients with dental erosion requires an analysis of the degree of structural damage. Patients affected by moderate to severe dental erosion are particularly challenging because complex occlusal reconstruction will be needed. Ultrathin bonded occlusal veneers represent a conservative alternative to traditional onlays and complete coverage crowns for the treatment of severe erosion. This article describes a complete mouth rehabilitation with ultrathin computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin occlusal veneers in a patient with a severely eroded dentition. In the maxillary anterior teeth, the bilaminar approach was chosen with lingual composite resin veneers and labial porcelain veneers. The main benefit of this approach is the possibility of using additive adhesive techniques, allowing only strategic reduction of sound dental structure or no preparation. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  8. Hot pressing and lithification of gouge during the Mount St. Helens 2004-2008 eruption: insights from high temperature deformation experiments

    Science.gov (United States)

    Ryan, Amy G.; Russell, James K.; Heap, Michael J.

    2017-04-01

    and 850°C. This change in axial strain-time curves with increasing T suggests the inclusion of a second densification process, aside from mechanical compaction, at elevated T. It is our hypothesis that solid-state sintering, a process wherein crystalline particles are fused together as a result of atomic diffusion across grain boundaries (i.e., the process occurring during the industrial production of ceramics by hot (isostatic) pressing), is the dominant mechanism operating at high T and under pressure. While viscous sintering (i.e. welding) operates in many "melt-glass-rich" volcanic systems, solid-state sintering has yet to be explored as a densification mechanism operating on fine granular crystalline volcanic materials at conditions and timescales relevant to volcanic processes.

  9. Influence of heat treatment and veneering on the storage modulus and surface of zirconia ceramic

    NARCIS (Netherlands)

    Siavikis, G.; Behr, M.; van der Zel, J.M.; Feilzer, A.J.; Rosentritt, M.

    2011-01-01

    Objectives: Glass-ceramic veneered zirconia is used for the application as fixed partial dentures. The aim of this investigation was to evaluate whether the heat treatment during veneering, the application of glass-ceramic for veneering or long term storage has an influence on the storage modulus of

  10. Influence of bruxism on survival of porcelain laminate veneers.

    Science.gov (United States)

    Granell-Ruíz, Maria; Agustín-Panadero, Rubén; Fons-Font, Antonio; Román-Rodríguez, Juan-Luis; Solá-Ruíz, María-Fernanda

    2014-09-01

    This study aims to determine whether bruxism and the use of occlusal splints affect the survival of porcelain laminate veneers in patients treated with this technique. Restorations were made in 70 patients, including 30 patients with some type of parafunctional habit. A total of 323 veneers were placed, 170 in patients with bruxism activity, and the remaining 153 in patients without it. A clinical examination determined the presence or absence of ceramic failure (cracks, fractures and debonding) of the restorations; these incidents were analyzed for association with bruxism and the use of splints. Analysis of the ceramic failures showed that of the 13 fractures and 29 debonding that were present in our study, 8 fractures and 22 debonding were related to the presence of bruxism. Porcelain laminate veneers are a predictable treatment option that provides excellent results, recognizing a higher risk of failure in patients with bruxism activity. The use of occlusal splints reduces the risk of fractures.

  11. Masking properties of ceramics for veneer restorations.

    Science.gov (United States)

    Skyllouriotis, Andreas L; Yamamoto, Hideo L; Nathanson, Dan

    2017-10-01

    The translucency and opacity of ceramics play a significant role in emulating the natural color of teeth, but studies of the masking properties and limitations of dental ceramics when used as monolayer restorations are lacking. The purpose of this in vitro study was to determine the translucency of 6 materials used for veneer restorations by assessing their translucency parameters (TPs), contrast ratios (CRs), and potential to mask dark tooth colors. Ten square- or disk-shaped specimens (0.5-mm thickness, shade A2) were fabricated from Vitablocks Mark II (VMII; Vita Zahnfabrik), IPS e.max CAD LT (EMXC LT; Ivoclar Vivadent AG), IPS e.max CAD HT (EMXC HT; Ivoclar Vivadent AG), IPS Empress CAD LT (EMP LT; Ivoclar Vivadent AG), IPS e.max Press LT (EMXP LT; Ivoclar Vivadent AG), and CZR (CZR; Kuraray Noritake Dental Inc). Their luminance (Y) values over black and over white tiles were measured, followed by their color (CIELab) over black tiles and white tiles and shaded A2 (control group), A3.5, A4, and B4 acrylic resin blocks. All measurements were performed using a spectrophotometer in 2 different areas on each specimen. Then CRs, TPs, and color differences (over shaded backgrounds) were determined. Data were subjected to 1-way and 2-way ANOVA (α=.05) for analysis. Mean CR values of EMXP LT were significantly higher than those of the other tested materials, whereas VMII and EMXC HT had the lowest values (Pmasking properties against the A4 background. The color differences of most tested ceramics were more acceptable when tested against the B4 background (ΔE*≤3.3). Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  12. Fracture strengths of chair‑side‑generated veneers cemented with ...

    African Journals Online (AJOL)

    2014-06-09

    Jun 9, 2014 ... Group 1), CAD/CAM‑fabricated veneers cemented with a glass fiber ... specimens were tested with a universal testing machine after thermal cycling treatment. ... The purpose of the current in vitro study is to determine the ..... fracture resistance of fiber reinforced cups‑replacing composite restorations.

  13. The changing veneer and plywood industry of Michigan and Wisconsin.

    Science.gov (United States)

    Gary R. Lindell; Lewis T. Hendricks

    1972-01-01

    Analyzes trends in the hardwood veneer and plywood industry of Michigan and Wisconsin between 1964 and 1969. In that period, red oak and hard maple replaced yellow birch as the major species used. Log supplies were adequate. Wall paneling was the major end market with doorskins next. Excess plywood producing capacity is a chronic problem.

  14. Wettability and Impact Performance of Wood Veneer/Polyester Composites

    Directory of Open Access Journals (Sweden)

    Shayesteh Haghdan

    2015-07-01

    Full Text Available Fiber-reinforced thermosetting composites have been of interest since the 1940s due to their ease of use in processing, fast curing times, and high specific stiffness and strength. While the use of plant fibers in a polyester matrix has been thoroughly studied, only limited information is available regarding using wood as reinforcement. In this study, composites of thin wood veneer and a polyester matrix were made and the difficulties in the lamination and curing processes were investigated. Sheets of Douglas fir, maple, and oak veneers using a catalyzed polyester resin were assembled as unidirectional, balanced, and unbalanced cross-ply laminates. These were compared to control specimens using glass fiber as reinforcement. The impact properties of the samples, with respect to the laminate thicknesses, were characterized using a drop-weight impact tester. The wettability and surface roughness of unsanded and sanded wood veneers were also investigated. Results showed that Douglas fir cross-ply laminates had an impact energy equivalent to glass fiber laminates, making them an interesting alternative to synthetic fiber composites. Wood/polyester laminates absorbed a considerable amount of energy through a higher number of fracture modes. The balanced lay-up limited twisting of the wood/polyester composites. The lowest contact angle and highest wettability were observed in unsanded Douglas fir veneers.

  15. Effect of Silviculture on the Yield and Quality of Veneers

    Science.gov (United States)

    Leslie H. Groom; Ray Newbold; Jim Guldin

    2002-01-01

    The structural and aesthetic value of wood is typically sacrificed in an attempt to meet demand. This paper addresses the financial and quality aspects of silvicultural choices as it relates to wood veneers. Five trees each were harvested from an uneven-aged stand and from the following even- aged stands: intensive plantation, conventional plantation, and natural...

  16. In situ polymerization of polyaniline in wood veneers.

    Science.gov (United States)

    Trey, Stacy; Jafarzadeh, Shadi; Johansson, Mats

    2012-03-01

    The present study describes the possibility to polymerize aniline within wood veneers to obtain a semi-conducting material with solid wood acting as the base template. It was determined that it is possible to synthesize the intrinsically conductive polymer (ICP) polyaniline in situ within the wood structure of Southern yellow pine veneers, combining the strength of the natural wood structure with the conductivity of the impregnated polymer. It was found that polyaniline is uniformly dispersed within the wood structure by light microscopy and FT-IR imaging. A weight percent gain in the range of 3-12 wt % was obtained with a preferential formation in the wood structure and cell wall, rather than in the lumen. The modified wood was found to be less hydrophilic with the addition of phosphate doped polyaniline as observed by equilibrium water swelling studies. While wood itself is insulating, the modified veneers had conductivities of 1 × 10(-4) to 1 × 10(-9) S cm(-1), demonstrating the ability to tune the conductivity and allowing for materials with a wide range of applications, from anti-static to charge-dispersing materials. Furthermore, the modified veneers had lower total and peak heat releases, as determined by cone calorimetry, because of the char properties of the ICP. This is of interest if these materials are to be used in building and furniture applications where flame retardance is of importance. © 2012 American Chemical Society

  17. Porcelain veneer post-bonding crack repair by resin infiltration

    NARCIS (Netherlands)

    Gresnigt, Marco; Magne, Michel; Magne, Pascal

    2017-01-01

    Ceramic laminate veneer restorations are indicated in several clinical situations. Indirect restorations are usually chosen if the less-invasive options - bleaching, resin infiltration, or composite resin restorations - are not possible, or when it is too difficult to achieve an esthetically

  18. Fabrication of Al-based composites reinforced with in situ devitrified Al{sub 84}Ni{sub 8.4}Y{sub 4.8}La{sub 1.8}Co{sub 1} particles by hot pressing consolidation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Qing, E-mail: buaayq00@gmail.com; Zhang, Yitan; Zhang, Haiping; Zheng, Ruixiao; Xiao, Wenlong; Ma, Chaoli, E-mail: machaoli@buaa.edu.cn

    2015-11-05

    In this study, Al{sub 84}Ni{sub 8.4}Y{sub 4.8}La{sub 1.8}Co{sub 1} particles reinforced Al-based composites were prepared by hot pressing sintering and subsequent hot extrusion. The glassy powders were produced by gas atomization and then employed to mechanical milling. After hot pressing sintering, the nano-scale intermetallic compounds precipitated from metallic glass matrix due to higher temperature than super-cooled liquid region. The mechanical properties of 2024 alloy were improved by addition of glassy particles. The ultimate compressive stress increased from 482 MPa for 2024 alloy to 545 MPa, 627 MPa and 735 MPa for composites with 20 w.t.% 40 w.t.% and 60 w.t.% glassy powders addition, respectively, together with considerable fracture strain ranging between 2.9% and 13.6%. And the mechanical properties could be predicted by using the Rule of Mixture, which predicts the mechanical properties of the bulks from the volume weighed average of the constituent properties. - Highlights: • The composites are fabricate by hot pressing and extrusion. • The single phase of amorphous alloy is obtained by sieving. • The nano-scale compounds precipitates from glassy matrix. • The compressive strength reaches to the value of 735 MPa. • The strength can fit well with rule of mixture.

  19. Novel UV cured polymers for coating and recycling cellulosics, application to a unique paper / veneer from the waste banana tree

    International Nuclear Information System (INIS)

    Dennis, G.R.; Garnett, J.L.; Jarrett, K.J.

    2007-01-01

    Work involving UV curing and cure-grafting processes on material from the waste banana tree has been performed. Water compatible oligomers of unique structure and processing novel properties have been used in this treatment. The material from the waste banana tree has been obtained by a peeling process and can be treated either as a type of paper or as a modified timber veneer leading to two general lines of potential commercial products. The peeled product is coated with formulations containing the novel oligomers and UV cured. The advantages of using these unique water compatible oligomers in all general UV curing systems are discussed. The effect of including nanoparticle fillers in these coating formulations is considered. The effect of the presence of lignin in the banana ply paper on the curing process is examined by comparing the banana ply paper curing data with analogous results from a pure cellulose Whatman 41 paper. Two UV lamps have been used in these studies, a Fusion F-300 and a Con-Trol-Cure LED, the latter shown to be safer from body exposure considerations because it operates in a 385-405 nm wavelength band. A mechanism for the curing and cure-grafting process on banana ply paper/veneer has been proposed. The commercial potential of this process is discussed especially the economic advantages of using the banana ply paper/veneer which is not chemically pulped. (Author)

  20. Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

    Science.gov (United States)

    Inokoshi, M; Yoshihara, K; Nagaoka, N; Nakanishi, M; De Munck, J; Minakuchi, S; Vanmeensel, K; Zhang, F; Yoshida, Y; Vleugels, J; Naert, I; Van Meerbeek, B

    2016-01-01

    The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical

  1. Evidence of yttrium silicate inclusions in YSZ-porcelain veneers.

    Science.gov (United States)

    Stoner, Brian R; Griggs, Jason A; Neidigh, John; Piascik, Jeffrey R

    2014-04-01

    This report introduces the discovery of crystalline defects that can form in the porcelain veneering layer when in contact with yttria-stabilized zirconia (YSZ). The focus was on dental prostheses and understanding the defects that form in the YSZ/porcelain system; however the data reported herein may have broader implications toward the use and stability of YSZ-based ceramics in general. Specimens were cut from fully sintered YSZ plates and veneering porcelain was applied (X-ray (EDAX) was used for microstructural and elemental analysis. EDAX, for chemical analysis and transmission electron diffraction (TED) for structural analysis were both performed in the transmission electron microscope (TEM). Additionally, in order to spatially resolve Y-rich precipitates, micro-CT scans were conducted at varying depths within the porcelain veneer. Local EDAX (SEM) was performed in the regions of visible inclusions and showed significant increases in yttrium concentration. TEM specimens also showed apparent inclusions in the porcelain and selected area electron diffraction was performed on these regions and found the inclusions to be crystalline and identified as either yttrium-silicate (Y2 SiO5 ) or yttrium-disilicate (Y2 Si2 O7 ). Micro-CT data showed that yttrium-silicate precipitates were distributed throughout the thickness of the porcelain veneer. Future studies are needed to determine whether many of the premature failures associated with this materials system may be the result of crystalline flaws that form as a result of high temperature yttrium diffusion near the surfaces of YSZ. © 2013 Wiley Periodicals, Inc.

  2. Opalescence of all-ceramic core and veneer materials.

    Science.gov (United States)

    Cho, Moon-Sang; Yu, Bin; Lee, Yong-Keun

    2009-06-01

    The enamel of natural teeth is opalescent, where there is light scattering of the shorter wavelengths of the visible spectrum, giving a tooth a bluish appearance in the reflected color and an orange/brown appearance in the transmitted color. The objective of this study was to determine the opalescence of all-ceramic core, veneer and layered specimens with a color measuring spectrophotometer. Colors of core (A2-corresponding shade), veneer (A2- and A3-corresponding shades) and layered (A2- and A3-layered) ceramics for all-ceramic restorations in clinically relevant thicknesses were measured in the reflectance and transmittance modes. The opalescence parameter (OP), which was calculated as the difference in blue-yellow coordinate (Deltab(*)) and red-green coordinate (Deltaa(*)), and the differences in blue-yellow coordinate (Deltab(*)) and in color (DeltaE(ab)(*)) between the reflected and transmitted colors were calculated. One-way ANOVA was performed for the OP values of the core, veneer and layered specimens by the kind of materials. Regression analysis was performed between the OP and Deltab(*), and the OP and DeltaE(ab)(*) values. The range of the OP value was 1.6-6.1, 2.0-7.1, 1.3-5.0 and 1.6-4.2 for the core, veneer, A2- and A3-layered specimens, respectively, all of which were significantly influenced by the kind of materials (pOpalescence varied by kind of ceramics. The OP values of ceramics were lower than those of tooth enamel. All-ceramic materials that can simulate the opalescence of natural teeth should be developed.

  3. Texturing of superconducting Bi-Pb-Sr-Ca-Cu-O ceramics by combining the effect of a magnetic field and hot pressing in one direction; Texturation des ceramiques supraconductrices Bi-Pb-Sr-Ca-Cu-O par combinaison des effets du champ magnetique et de la contrainte uniaxiale a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Noudem, J G

    1995-10-27

    Superconducting Bi-(Pb)-Sr-Ca-Cu-O (Bi:2223) ceramics have a weak 77 K transport critical current density (Jc) due to porosity and the presence of misaligned platelets. In order to obtain higher critical current densities in these materials, it is necessary to increase their density and induce a preferential crystallographic orientation. We have developed a texturing process using solidification in a magnetic field combined with hot pressing. The experimental set-up provides a uniaxial pressure of 60 MPa and temperature up to 1100 deg C in a magnetic field of 8 T. Magnetic melt texturing (MMT) proved to be very effective in producing bulk oriented samples of polycrystalline Bi:2223 (crystallite c-axis oriented parallel to the field direction). These samples have Jc values of up to 1450 A/cm{sup 2} and a density of 5.1 g/cm{sup 3}. The texturing by hot pressing (HP) gives homogeneous, dense ({approx} 6 g/cm{sup 3}; 95 % of the theoretical limit) ceramics with a Jc of 2500 A/cm{sup 2}. Tapes of Ag/Bi:2223 provided by Alcatel Alsthom were also successful textured using HP. Finally we have demonstrated that the combination of solidification in a magnetic field with hot pressing (MMHPT) improves both the texture and density of the samples. Moreover the samples are very homogeneous and mechanically resistant. The 77 K transport critical current densities have values up to 3800 A/cm{sup 2} and 1100 A/cm{sup 2} along the (ab) and c-axis respectively. We have demonstrated that these samples are of potential use a current limiters. (author) 146 refs.

  4. Masking ability of bi- and tri- laminate all-ceramic veneers on tooth-colored ceramic discs.

    Science.gov (United States)

    Farhan, Daniel; Sukumar, Smitha; von Stein-Lausnitz, Axel; Aarabi, Ghazal; Alawneh, Ahmad; Reissmann, Daniel R

    2014-01-01

    A predictable esthetic outcome is imperative when placing ceramic veneers. Discolored teeth pose a major challenge as sufficient material thickness is required to achieve a good esthetic result. There is limited evidence in the literature that compares the masking ability of multi-laminate veneers. The aim of this in-vitro study was to compare the masking ability of bi-laminate (BL) and tri-laminate (TL) all-ceramic veneers cemented on tooth-colored ceramic discs. A total of 40 veneers (shade A1, 10-mm diameter, 0.8-mm thick) were manufactured-20 BL veneers (0.4-mm pressable ceramic coping veneered with 0.4-mm thick enamel layer) and 20 TL veneers (0.4-mm coping veneered with 0.2-mm thick opaque interlayer and 0.2-mm thick enamel layer). A bonding apparatus was utilized to adhesively cement all veneers on the ceramic discs (shade A1), simulating teeth of light and dark color. The resulting groups (N = 10 each) were the reference groups (shade A1 ceramic base) BL-1 and TL-1 veneers, and the test groups (shade A4 ceramic base) BL-4 and TL-4 veneers. The color of the cemented veneers was measured using a spectrophotometer. The data were converted to CIE L*a*b* coordinates, and ΔE* were calculated to allow for statistical analysis. The color differences between the samples with the A1 and A4 ceramic bases were significantly lower when covered with TL veneers (mean ΔE*: 3.2 units) than with BL veneers (mean ΔE*: 4.0 units: p bi-laminate veneers. Patients with discolored/darker teeth may benefit from a more predictable esthetic result when teeth restored with tri-laminate rather than bi-laminate veneers. © 2014 Wiley Periodicals, Inc.

  5. Production and processing of Cu-Cr-Nb alloys

    International Nuclear Information System (INIS)

    Ellis, D.L.; Michal, G.M.; Orth, N.W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling

  6. Production and processing of Cu-Cr-Nb alloys

    Science.gov (United States)

    Ellis, David L.; Michal, Gary M.; Orth, Norman W.

    1990-01-01

    A new Cu-based alloy possessing high strength, high conductivity, and good stability at elevated temperatures was recently produced. This paper details the melting of the master alloys, production of rapidly solidified ribbon, and processing of the ribbon to sheet by hot pressing and hot rolling.

  7. Influence of framework color and layering technique on the final color of zirconia veneered restorations

    NARCIS (Netherlands)

    Aboushelib, M.N.; Dozic, A.; Liem, J.K.

    2010-01-01

    Objective: To investigate the influence of colored zirconia frameworks on the overall color match of zirconia- veneered restorations. Method and Materials: Identical natural and colored zirconia frameworks (Cercon Base, Degudent) were layered using a veneer ceramic (IPS e.max Ceram Dentin, Ivoclar

  8. Physical, mechanical, and fire properties of oriented strandboard with fire retardant treated veneers

    Science.gov (United States)

    Nadir Ayrilmis; Zeki Candan; Robert White

    2007-01-01

    This study evaluated physical, mechanical and fire properties of oriented strand boards (OSB) covered with fire retardant treated veneers. The beech (Fagus orientalis Lipsky) veneers were treated with either monoammonium phosphate, diammonium phosphate, lime water or a borax/boric acid (1 : 1 by weight) mixture. Physical and mechanical properties of the specimens were...

  9. Cone calorimeter testing of foam core sandwich panels treated with intumescent paper underneath the veneer (FRV)

    Science.gov (United States)

    Mark A. Dietenberger; Ali Shalbafan; Johannes Welling

    2017-01-01

    Surfaces of novel foam core sandwich panels were adhered with intumescent fire‐retardant paper underneath the veneers (FRV) to improve their flammability properties. The panels were evaluated by means of cone calorimeter test (ASTM E 1354). Variables tested were different surface layer treatments, adhesives used for veneering, surface layer thicknesses, and processing...

  10. Ultrathin CAD-CAM Ceramic Occlusal Veneers and Anterior Bilaminar Veneers for the Treatment of Moderate Dental Biocorrosion: A 1.5-Year Follow-Up.

    Science.gov (United States)

    Resende, T H; Reis, K R; Schlichting, L H; Magne, P

    2018-03-27

    Dental biocorrosion can produce a devastating impact on oral health. The restorative phase of the treatment should not cause additional damage of the remaining sound tooth structure. Ultrathin occlusal veneers are a conservative alternative to traditional onlays and complete crowns for the treatment of severe biocorrosive lesions. This strategy is explained in the present case report through a full-mouth rehabilitation of a patient with moderate biocorrosion. Maxillary anterior teeth were restored using the bilaminar technique (lingual direct composite veneers with labial ceramic veneers) and posterior teeth using ultrathin CAD-CAM ceramic occlusal veneers. The technical aspects required for the implementation of this new restorative design are presented with a special emphasis on the control of tooth preparation based on diagnostic wax-up, provisionalization, and the use of CAD-CAM technology.

  11. Origin and mixing timescale of Earth's late veneer

    Science.gov (United States)

    Prescher, C.; Allu Peddinti, D.; Bell, E. A.; Bello, L.; Cernok, A.; Ghosh, N.; Tucker, J.; Wielicki, M. M.; Zahnle, K. J.

    2012-12-01

    Experimental studies on the partitioning behavior of highly siderophile elements (HSE) between silicate and metallic melts imply that the Earth's mantle should have been highly depleted in these elements by core formation in an early magma ocean. However, present HSE contents of the Earth's mantle are ~3 orders of magnitude higher than that expected by experiments. The apparent over-abundance of HSE has commonly been explained by the addition of meteoritic material in the "late veneer" which describes the exogenous mass addition following the moon forming impact and concluding with the late heavy bombardment at ~3.8-3.9 Ga. The strongest evidence for this theory is that the platinum group element (PGE) contents in today's mantle are present in chondritic relative abundances, as opposed to a fractionated pattern expected with metal-silicate partitioning. Archean komatiites indicate that the PGE content of the Earth's mantle increased from about half their present abundances at 3.5 Ga to their present abundances at 2.9 Ga. This secular increase in PGE content suggests a progressive mixing of the late veneer material into the Earth's mantle. However, this time scale also implies that the whole mantle was relatively well mixed by 2.9 Ga. We use a compilation of existing isotopic and trace element data in order to constrain the origin and composition of the late veneer. We use PGE abundances, W abundances and W isotopic compositions in chondritic meteorites and the primitive upper mantle to compute the amount of mass delivered during the late veneer and find the late veneer mass to be ~0.6 % the mass of the bulk silicate Earth (consistent with earlier estimates). We also use the 187Re-187Os and 190Pt-186Os systems to constrain the composition and timing of delivery of the impacting population. We model the efficiency of mantle mixing in this time frame by using 3-dimensional numerical geodynamical simulations and geochemical constraints. Initial parameters include the

  12. Indirect veneer treatment of anterior maxillary teeth with enamel hypoplasia

    Directory of Open Access Journals (Sweden)

    Devi Eka Juniarti

    2010-09-01

    Full Text Available Background: Nowadays, aesthetic rehabilitation becomes a necessity. It is affected by patient’s background, especially career, social and economic status. The aesthetic abnormality of anterior teeth i.e discoloration, malposition and malformation can affect patient’s appearance, especially during smile. These dental abnormalities, as a result, can decrease patient’s performance. Dental malformation, for instance, can be caused by developmental tooth defect, such as enamel hypoplasia. Enamel hypoplasia is a developmental defect caused by the lack of matrix amount which leads to thin and porous enamel. Enamel hypoplasia can also be caused by matrix calcification disturbance starting from the formation and development of enamel matrix causing defect and permanent changes which can occur on one or more tooth. Purpose: The aim of the study is to improve dental discoloration and tooth surface texture on anterior maxillary teeth with enamel hypoplasia by using indirect veneer with porcelain material. Case: A 20 years-old woman with enamel hypoplasia came to the Dental Hospital, Faculty of Dentistry Airlangga University. The patient wanted to improve her anterior maxillary teeth. It is clinically known that there were some opaque white spots (chalky spotted and porous on anterior teeth’s surface. Case management: Indirect veneer with porcelain material had been chosen as a restoration treatment which has excellent aesthetics and strength, and did not cause gingival irritation. As a result, the treatment could improve the confidence of the patient, and could also make their function normal. Conclusion: Indirect veneer is an effective treatment, which can improve patient’s appearance and self confidence.Latar belakang: Saat ini perbaikan estetik menjadi suatu kebutuhan. Kebutuhan akan estetik dipengaruhi latar belakang penderita, terutama karir, status sosial dan ekonomi. Hal ini disebabkan, kelainan estetik seperti diskolorasi, malposisi

  13. Fracture mechanics analyses of ceramic/veneer interface under mixed-mode loading.

    Science.gov (United States)

    Wang, Gaoqi; Zhang, Song; Bian, Cuirong; Kong, Hui

    2014-11-01

    Few studies have focused on the interface fracture performance of zirconia/veneer bilayered structure, which plays an important role in dental all-ceramic restorations. The purpose of this study was to evaluate the fracture mechanics performance of zirconia/veneer interface in a wide range of mode-mixities (at phase angles ranging from 0° to 90°), and to examine the effect of mechanical properties of the materials and the interface on the fracture initiation and crack path of an interfacial crack. A modified sandwich test configuration with an oblique interfacial crack was proposed and calibrated to choose the appropriate geometry dimensions by means of finite element analysis. The specimens with different interface inclination angles were tested to failure under three-point bending configuration. Interface fracture parameters were obtained with finite element analyses. Based on the interfacial fracture mechanics, three fracture criteria for crack kinking were used to predict crack initiation and propagation. In addition, the effects of residual stresses due to coefficient of thermal expansion mismatch between zirconia and veneer on the crack behavior were evaluated. The crack initiation and propagation were well predicted by the three fracture criteria. For specimens at phase angle of 0, the cracks propagated in the interface; whereas for all the other specimens the cracks kinked into the veneer. Compressive residual stresses in the veneer can improve the toughness of the interface structure. The results suggest that, in zirconia/veneer bilayered structure the veneer is weaker than the interface, which can be used to explain the clinical phenomenon that veneer chipping rate is larger than interface delamination rate. Consequently, a veneer material with larger fracture toughness is needed to decrease the failure rate of all-ceramic restorations. And the coefficient of thermal expansion mismatch of the substrates can be larger to produce larger compressive

  14. 3D-characterization of the veneer-zirconia interface using FIB nano-tomography.

    Science.gov (United States)

    Mainjot, Amélie K; Douillard, Thierry; Gremillard, Laurent; Sadoun, Michaël J; Chevalier, Jérôme

    2013-02-01

    The phenomena occurring during zirconia frameworks veneering process are not yet fully understood. In particular the study of zirconia behavior at the interface with the veneer remains a challenge. However this interface has been reported to act on residual stress in the veneering ceramic, which plays a significant role in clinical failures such as chipping. The objective of this study was thus to investigate the veneer-zirconia interface using a recent 3D-analysis tool and to confront these observations to residual stress measurements in the veneering ceramic. Two cross-sectioned bilayered disc samples (veneer on zirconia), exhibiting different residual stress profiles in the veneering ceramic, were investigated using 2D and 3D imaging (respectively Scanning Electron Microscopy (SEM) and Focused Ion Beam nanotomography (FIB-nt), associated with chemical analysis by Energy Dispersive X-ray Spectroscopy (EDS). The observations did not reveal any structural change in the bulk of zirconia layer of both samples. However the presence of structural alterations and sub-surface microcracks were highlighted in the first micrometer of zirconia surface, exclusively for the sample exhibiting interior tensile stress in the veneering ceramic. No interdiffusion phenomena were observed. FIB nanotomography was proven to be a powerful technique to study the veneer-zirconia interface. The determination of the origin and the nature of zirconia alterations need to be further studied. The results of the present study support the hypothesis that zirconia surface property changes could be involved in the development of tensile stress in the veneering ceramic, increasing the risk of chipping. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  15. [A preliminary study on the color effect of IPS Empress all-ceramic veneers].

    Science.gov (United States)

    Li, Zhi-yong; Cheng, Xiang-rong; Wang, Yi-ning

    2004-09-01

    To evaluate the opaquing capacity, color compatibility and stability of IPS Empress all-ceramic veneers. A total of 86 IPS Empress all-ceramic veneers were made for 18 patients. The patients were divided into three groups: Group A was tetracycline teeth, 64 veneers for 5 patients; Group B was non-tetracycline teeth, 22 veneers for 13 patients; Group C was 22 natural vital teeth with normal color as control group. Before and after veneers were inserted, ShadeEye NCC was employed to obtain L * a * b * values of each tooth. The values of cemented veneers used as the baseline, the L * a * b * values of each veneer were measured half a year, 1 year, and 2 years after restoration respectively. All L * a * b * values at different evaluation times were analyzed by SPSS 10.0. Before and after veneers were restored, the L * a * b * values of both Group A and Group B were significantly different, the color difference being 5.01 and 4.15 respectively. The color difference between Group A and selected shade guides was 2.45. Compared with the baseline value, the L * value of Group A significantly decreased 2 years after restoration, but the DeltaE of different evaluation times was not significantly different. The color difference between Group B and Group C was 0.22 and there was no significant color difference after restoration. IPS Empress all-ceramic veneers have excellent opaquing capacity, color compatibility and stability to non-tetracycline teeth. To tetracycline teeth IPS Empress all-ceramic veneers have a certain opaquing capacity, but they cannot completely match with shade guides; the L * value is significantly different after restoration and further studies are needed to evaluate its color effect.

  16. [An in vitro study of the fracture strength of tooth preparations for Empress 2 veneers and crowns and mandibular incisors restored with Empress 2 veneers and crowns].

    Science.gov (United States)

    Wei, Xue; Li, Yan

    2009-12-01

    To compare the fracture resistance of mandibular incisors' preparations for veneers and crowns, mandibular incisors restored with Empress 2 veneers and crowns. 50 human mandibular incisors were randomly divided into five groups. Each group consisted of ten teeth and the treatment obtained as follows: A, tooth preparations for veneers; B, tooth preparations for crowns; C, teeth restored with veneers; D, teeth restored with crowns; E, untreated group. The teeth received standardized preparation and the restorations were manufactured with Empress 2 system and cemented with resin luting agent. The fracture resistances of teeth were measured by Instron universal testing machine and statistically analyzed with one-way ANOVA. The fracture resistances of A, B, C, D, E were (576.11 +/- 91.53), (204.13 +/- 85.88), (451.50 +/- 116.81), (386.16 +/- 117.75) and (566.05 +/- 121.37) N, respectively. The statistical analysis demonstrated significant differences between five groups. There were no significant differences between group A and E, group C and D. Tooth preparations for veneers did not significantly reduce the fracture resistance of mandibular incisor. The fracture resistance of teeth restored with Empress 2 veneers and crowns did not significantly differ from each other.

  17. Spherical powder for retaining thermosetting acrylic resin veneers.

    Science.gov (United States)

    Tanaka, T; Atsuta, M; Uchiyama, Y; Nakabayashi, N; Masuhara, E

    1978-03-01

    1. Nine different sizes of spherical powder were prepared, and their effectiveness as retentive devices was evaluated against those available commercially. 2. Smaller-diameter spherical powder (No. 5) gave the best results of all retaining devices tested. 3. The physical properties of the resins play an important role in the retentive strength with No. 5 retention beads. The retentive strength was reduced when brittle resin was used. 4. The retentive strength of the resin veneer was greatly affected by the angle of stress at the incisal resin. The retentive strength increased as the angle between the longitudinal axis of the specimen and the direction of stress decreased.

  18. Late Veneer consequences on Venus' long term evolution

    Science.gov (United States)

    Gillmann, C.; Golabek, G.; Tackley, P. J.; Raymond, S. N.

    2017-12-01

    Modelling of Venus' evolution is able to produce scenarios consistent with present-day observation. These results are however heavily dependent on atmosphere escape and initial volatile inventory. This primordial history (the first 500 Myr) is heavily influenced by collisions. We investigate how Late Veneer impacts change the initial state of Venus and their consequences on its coupled mantle/atmosphere evolution. We focus on volatile fluxes: atmospheric escape and mantle degassing. Mantle dynamics is simulated using the StagYY code. Atmosphere escape covers both thermal and non-thermal processes. Surface conditions are calculated with a radiative-convective model. Feedback of the atmosphere on the mantle through surface temperature is included. Large impacts are capable of contributing to atmospheric escape, volatile replenishment and energy transfer. We use the SOVA hydrocode to take into account volatile loss and deposition during a collision. Large impacts are not numerous enough to substantially erode Venus' atmosphere. Single impacts don't have enough eroding power. Swarms of small bodies (history of the planet and leads to lower present-day surface temperatures. Total depletion of the mantle seems unlikely, meaning either few large impacts (1 to 4) or low energy (slow, grazing…) collisions. Combined with the lack of plate tectonics and volatile recycling in the interior of Venus, Late Veneer collisions could help explain why Venus seems dry today.

  19. Fabrication of Hydrophobic Surface on Wood Veneer via Electroless Nickel Plating Combined with Chemical Corrosion

    Directory of Open Access Journals (Sweden)

    Zhaojun Tang

    2015-12-01

    Full Text Available Birch veneers were coated with Ni-P films by a combined process of KBH4 activation and electroless plating. The plated veneers were further chemically corroded to obtain hydrophobic surfaces on wood. The effect of chemical corrosion on the contact angle of the veneers was investigated. The hydrophobic veneers were characterized by X-ray photo electron spectroscopy (XPS, scanning electron microscopy (SEM, and X-ray diffraction (XRD. The surface contact angle of birch veneer before and after it was plated with Ni-P alloy coating was 41º and 121º, respectively. The contact angle reached 136.7º when the nickel-coated veneers were corroded in CuSO4 aqueous solution for 30 min. XPS analysis showed that Cu0 cluster doped with little CuO formed on the corroded surface of Ni-P alloy film after chemical corrosion. SEM and XRD showed that rough copper clusters formed on the surface of the wood veneer and revealed the reason of the surface hydrophobicity. This study provides a new pathway for fabricating hydrophobic wood.

  20. Cyclic testing of porcelain laminiate veneers on superficial enamel and dentin: Pressed vs. conventional layered porcelain

    Science.gov (United States)

    Tawde, Shweta

    Statement of Problem: Clinicians are inclined towards more aggressive teeth preparations to accommodate the thickness of the veneering material. The principle of conservative tooth preparation is compromised. Purpose: By using a conservative approach to treatment with porcelain veneers, long-lasting, esthetic and functional results may be achieved. Sacrificing as little tooth structure as possible and conserving the supporting tissues will facilitate prospective patients. Materials and Methods: Forty extracted human maxillary and mandibular canines were selected. The teeth were divided into one of two groups (pressable and stackable) and further subdivided according to tooth substrate (all-enamel or mixed enamel-dentin exposure). Twenty canine teeth were allotted to the pressable veneer group and 20 were allotted to the stackable veneer group. Of the 20 teeth in the pressable group, all were pressed with a lithium disilicate ceramic system (IPS e.max Press), 10 with labial tooth reduction of 0.3-0.5 mm maintaining superficial enamel (PEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (PDN). Of the 20 teeth in the stackable group, all were stacked/ layered with conventional feldspathic porcelain (Fortune; Williams/ Ivoclar); with labial veneer reduction of 0.3-0.5 mm maintaining superficial enamel (SEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (SDN). Silicon putty matrix was fabricated prior to teeth preparation to estimate the teeth reduction. The prepared facial reduction was limited to the incisal edge. No incisal or palatal/lingual reduction was performed. Impressions of the prepared teeth were taken in medium/light-bodied PVS. Master casts were made in Resin Rock. The stackable group specimens were made with fabricating refractory dies and after following the recommended steps of laboratory procedure, stackable veneers were processed. The pressable group

  1. [Preliminary study of bonding strength between diatomite-based dental ceramic and veneering porcelains].

    Science.gov (United States)

    Lu, Xiao-li; Gao, Mei-qin; Cheng, Yu-ye; Zhang, Fei-min

    2015-04-01

    In order to choose the best veneering porcelain for diatomite-based dental ceramic substrate, the bonding strength between diatomite-based dental ceramics and veneering porcelains was measured, and the microstructure and elements distribution of interface were analyzed. The coefficient of thermal expansion (CTE) of diatomite-based dental ceramics was detected by dilatometry. Three veneering porcelain materials were selected with the best CTE matching including alumina veneering porcelain (group A), titanium porcelain veneering porcelain (group B), and E-max veneering porcelain (group C). Shear bonding strength was detected. SEM and EDS were used to observe the interface microstructure and element distribution. Statistical analysis was performed using SPSS 17.0 software package. The CTE of diatomite-based dental ceramics at 25-500 degrees centigrade was 8.85×10-6K-1. The diatomite-based substrate ceramics combined best with group C. Shear bonding strength between group A and C and group B and C both showed significant differences(P<0.05). SEM and EDS showed that the interface of group C sintered tightly and elements permeated on both sides of the interface. The diatomite-based substrate ceramics combines better with E-max porcelain veneer.

  2. Fracture and Fatigue Resistance of Cemented versus Fused CAD-on Veneers over Customized Zirconia Implant Abutments.

    Science.gov (United States)

    Nossair, Shereen Ahmed; Aboushelib, Moustafa N; Morsi, Tarek Salah

    2015-01-05

    To evaluate the fracture mechanics of cemented versus fused CAD-on veneers on customized zirconia implant abutments. Forty-five identical customized CAD/CAM zirconia implant abutments (0.5 mm thick) were prepared and seated on short titanium implant abutments (Ti base). A second scan was made to fabricate 45 CAD-on veneers (IPS Empress CAD, A2). Fifteen CAD-on veneers were cemented on the zirconia abutments (Panavia F2.0). Another 15 were fused to the zirconia abutments using low-fusing glass, while manually layered veneers served as control (n = 15). The restorations were subjected to artificial aging (3.2 million cycles between 5 and 10 kg in a water bath at 37°C) before being axially loaded to failure. Fractured specimens were examined using scanning electron microscopy to detect fracture origin, location, and size of critical crack. Stress at failure was calculated using fractography principles (alpha = 0.05). Cemented CAD-on restorations demonstrated significantly higher (F = 72, p CAD-on and manually layered restorations. Fractographic analysis of fractured specimens indicated that cemented CAD-on veneers failed due to radial cracks originating from the veneer/resin interface. Branching of the critical crack was observed in the bulk of the veneer. Fused CAD-on veneers demonstrated cohesive fracture originating at the thickest part of the veneer ceramic, while manually layered veneers failed due to interfacial fracture at the zirconia/veneer interface. Within the limitations of this study, cemented CAD-on veneers on customized zirconia implant abutments demonstrated higher fracture than fused and manually layered veneers. © 2014 by the American College of Prosthodontists.

  3. Porcelain veneer post-bonding crack repair by resin infiltration.

    Science.gov (United States)

    Gresnigt, Marco; Magne, Michel; Magne, Pascal

    Ceramic laminate veneer restorations are indicated in several clinical situations. Indirect restorations are usually chosen if the less-invasive options - bleaching, resin infiltration, or composite resin restorations - are not possible, or when it is too difficult to achieve an esthetically pleasing result in the long term. Bonded indirect partial restorations are highly dependent on their adhesive interface, as these thin restorations have a relatively low cohesive strength. Therefore, preservation of sound enamel, conditioning of the restorations and of the substrate, and luting procedures are of paramount importance for a successful outcome. Even when utmost care is taken during every step of the procedure, failures such as fractures, chipping, or marginal discoloration and defects sometimes occur. Only very few of these cases of failure are presented or are a subject of interest. In this case presentation, a fracture repair is performed using an infiltration technique with a resin composite material.

  4. Surface roughness of composite resin veneer after application of herbal and non-herbal toothpaste

    Science.gov (United States)

    Nuraini, S.; Herda, E.; Irawan, B.

    2017-08-01

    The aim of this study was to find out the surface roughness of composite resin veneer after brushing. In this study, 24 specimens of composite resin veneer are divided into three subgroups: brushed without toothpaste, brushed with non-herbal toothpaste, and brushed with herbal toothpaste. Brushing was performed for one set of 5,000 strokes and continued for a second set of 5,000 strokes. Roughness of composite resin veneer was determined using a Surface Roughness Tester. The results were statistically analyzed using Kruskal-Wallis nonparametric test and Post Hoc Mann-Whitney. The results indicate that the highest difference among the Ra values occurred within the subgroup that was brushed with the herbal toothpaste. In conclusion, the herbal toothpaste produced a rougher surface on composite resin veneer compared to non-herbal toothpaste.

  5. Study on Flexural Creep Parameters of Overlayed Particleboard by Natural and Melaminated Veneers

    Directory of Open Access Journals (Sweden)

    Abdollah Najafi

    2012-06-01

    Full Text Available In this study, effects of natural and artificial veneer on flexural creep behavior of particleboard was investigated. Particleboard panels were prepared from Pars Neopan industries with 660 kg/m3 density and then overlaid by natural and melamine veneers. Their creep behavior was compared to control particleboard. For evaluating maximum bending load in static flexural test, specimens were cut from panels according to ASTM D 1037 with dimensions of 370×50×16 mm. Then, The flexural creep tests at 20% and 40% of failure bending load was applied to test specimens. Results of flexural tests indicated that the MOR and MOE values of veneered particleboard were highest. Results of creep showed that levels of stresses are effective on all creep parameters, but showed less effect on relative creep. Also, creep parameters less effective on specimens overlaid by natural veneer.

  6. Color management of porcelain veneers: influence of dentin and resin cement colors.

    Science.gov (United States)

    Dozic, Alma; Tsagkari, Maria; Khashayar, Ghazal; Aboushelib, Moustafa

    2010-01-01

    Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence of natural dentin and resin cement colors on final color match of porcelain veneers. A preselected shade tab (A1) was chosen as the target color for a maxillary central incisor, and its color parameters (L*a*b*) were measured using a digital spectrophotometer (SpectroShade, MHT). Nine natural dentin colors (Natural Die Material, Ivoclar Vivadent) representing a wide range of tooth colors were used to prepare resin replicas of the maxillary central incisor with a standard preparation for porcelain veneers. The prepared porcelain veneers (IPS Empress Esthetic, A1, 0.6 mm thick, Ivoclar Vivadent) were cemented on the resin dies (nine groups of natural dentin colors) using seven shades of resin cement (Variolink Veneers, Ivoclar Vivadent). The L*a*b* values of the cemented veneers were measured, and DE values were calculated against the preselected target color (A1). DE greater than 3.3 was considered as a significant color mismatch detectable by the human eye. The seven shades of resin cement had no significant influence on the final color of the veneers, as the measured DE values were almost identical for every test group. On the other hand, the color of natural dentin was a significant factor that influenced final color match. None of the 63 tested combinations (nine natural dentin colors and seven resin cement colors) produced an acceptable color match. Thin porcelain veneers cannot mask underlying tooth color even when different shades of resin cement are used. Incorporation of opaque porcelain (high chroma) may improve final color match.

  7. Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

    Science.gov (United States)

    Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

    2010-01-01

    This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

  8. The Effect of Core and Veneering Design on the Optical Properties of Polyether Ether Ketone.

    Science.gov (United States)

    Zeighami, S; Mirmohammadrezaei, S; Safi, M; Falahchai, S M

    2017-12-01

    This study aimed to evaluate the effect of core shade and core and veneering thickness on color parameters and translucency of polyether ether ketone (PEEK). Sixty PEEK discs (0.5 and 1 mm in thickness) with white and dentine shades were veneered with A2 shade indirect composite resin with 0.5, 1 and 1.5 mm thickness (n=5). Cores without the veneering material served as controls for translucency evaluation. Color parameters were measured by a spectroradiometer. Color difference (ΔE₀₀) and translucency parameters (TP) were computed. Data were analyzed using one-way ANOVA and Tukey's test (for veneering thickness) and independent t-test (for core shade and thickness) via SPSS 20.0 (p⟨0.05). Regarding the veneering thickness, white cores of 0.5 mm thickness showed significant differences in all color parameters. In white cores of 1 mm thickness and dentine cores of 0.5 and 1 mm thickness, there were statistically significant differences only in L∗, a∗ and h∗. The mean TP was significantly higher in all white cores of 1 mm thickness than dentine cores of 1 mm. Considering ΔE₀₀=3.7 as clinically unacceptable, only three groups had higher mean ΔE₀₀ values. Core shade, core thickness, and the veneering thickness affected the color and translucency of PEEK restorations. Copyright© 2017 Dennis Barber Ltd.

  9. Effect of various intermediate ceramic layers on the interfacial stability of zirconia core and veneering ceramics.

    Science.gov (United States)

    Yoon, Hyung-In; Yeo, In-Sung; Yi, Yang-Jin; Kim, Sung-Hun; Lee, Jai-Bong; Han, Jung-Suk

    2015-01-01

    The purposes of this study were to evaluate the effects of intermediate ceramics on the adhesion between the zirconia core and veneer ceramics. The polished surfaces of fully sintered Y-TZP blocks received three different treatments: (1) connector (C), (2) liner (L) or (3) wash layer (W). All the treated zirconia blocks were veneered with either (a) fluorapatite glass-ceramic (E) or (b) feldspathic porcelain (V) and divided into four groups (CE, CV, LE and WV). For the control group, the testing surfaces of metal blocks were veneered with feldspathic porcelain (VM). A half of the samples in each group (n = 21) were exposed to thermocycling, while the other half of the specimens were stored at room temperature under dry conditions. All specimens were subjected to the shear test and the failed surfaces were microscopically examined. The elemental distribution at the zirconia core/veneer interface was analyzed. The specimens in Groups CE and CV exhibited significantly greater mean bond strength values than those in Groups LE and WV, respectively (p ceramic substances into the zirconia surface. A glass-ceramic based connector is significantly more favorable to core/veneer adhesion than the other intermediate ceramics evaluated in the study. However, thermal cycling affected the bond strength at the core/veneer interface differently according to the intermediate ceramics.

  10. Testing the Late-Veneer hypothesis with selenium isotopes

    Science.gov (United States)

    Labidi, J.; Koenig, S.; Bennett, N.; Kurzawa, T.; Aierken, E.; Shahar, A.; Schoenberg, R.

    2016-12-01

    Selenium (Se) is a siderophile element displaying an excess abundance in Earth's mantle compared to experimental predictions [1], which may be attributed to the Late-Veneer. As Se is also volatile, testing the late-veneer addition of Se can constrain the origin of other volatile elements on Earth. Here we combine high-precision Se isotope measurements of metal-silicate partitioning experiments and chondrites to assess whether planetary differentiation could leave a measurable Se isotopic signature on planetary mantles. We performed Se isotopic measurements of 5 metal-silicate partitioning experiments and 20 chondrites of all major classes. Experiments were conducted at 1 GPa and 1650 C for 1 to 4 hours using the piston-cylinder apparatus at Carnegie's Geophysical Laboratory. After wet chemistry, data were obtained on a ThermoFisher Scientific™ NeptunePlus MC-ICP-MS at the University of Tübingen with a 74Se/77Se double spike technique. δ82/76Se values are given relative to NIST SRM-3149 and the external reproducibility calculated from duplicate meteorite analyses is ≤ 0.1‰ (2 s.d.). Chondrites vary over a 0.8‰ range of δ82/76Se values. CIs and CMs show evidence for heavier 82Se/76Se ratios, likely due to mixing processes in the proto-planetary nebula. When these isotopically heavier meteorites are excluded, remaining chondrites have δ82/76Se values varying over a 0.3‰ range, within uncertainty of previous results [2]. We suggest that these chondrites may be used to estimate a δ82/76Se value of bulk planets. At the conditions of our experiments, the partition coefficients for Se log Dmetal-silicate range from 0.7±0.1 to 1.9±0.1, consistent with previous work [1]. A small but resolvable Se isotopic fractionation was observed: 82Se/76Se ratios were enriched by ≤ 0.5‰ in the silicates relative to the metals. Thus, given current uncertainties for Se isotopic measurements, marginal differences between planetary mantles and chondrites may be resolved

  11. [Study on color of thermosetting resin for veneer crown].

    Science.gov (United States)

    Kamitomai, H

    1989-02-01

    Based on the viewpoint that stresses the importance of achieving natural colors and forms for veneer crown, four representative kinds of thermosetting resins were investigated colorimetrically in an attempt to clarify the relationship between the thickness and color of resins in opaque, dentin and enamel colors respectively. A spectrophotometer was used to measure the colors, the CIE colorimetric system employed to show the readings, and the CIE 1964 U*V*W* space was utilized to indicate the color differences, with the following results. 1. In the case of dentin, certain specific colors were observed for thickness of 1.3 to 1.8 mm when used alone, but when applied over opaque the range was 0.2 to 0.5 mm lower than when used alone. 2. Enamel resins were grouped into two types according to different color groups, one group similar to achromatic color with low limpidity and the other similar to the dentin color with high limpidity. The former type became more grayer with an increase in thickness when applied over dentin. The latter type showed no difference in color even when the thickness increased. This study has shown that the facing color results vary depending on the color properties of the different resins used. Therefore, it is advisable that careful consideration be given to these differencies in order to achieve the intended color facing.

  12. Effect of Sandblasting on Shear Bond Strength Composite Resin Veneer

    Directory of Open Access Journals (Sweden)

    Octarina Octarina

    2013-07-01

    Full Text Available Attachment between restoration and enamel surface in indirect resin composite veneer restoration (IRCV is obtained using multi-step (MS resin cement. Recently, a one step self-adhesive dual-cured resin cement (SADRC was introduced. Objective: To determine the effect of sandblasting on shear bond strength (SBS of IRCV to enamel using MS resin cement and SADRC. Methods: Forty specimens of buccal surface of enamel human were light-cured in Solidilite chamber and were divided into two groups: IRCV without sandblasting (n=20 and with sandblasting for 10 seconds (n=20 and then bonded to enamel using MS (n=10 and SADRC (n=10, respectively. After 24h SBS of specimens were tested using a Universal Testing Machine. Data were analyzed statistically by one-way ANOVA. Results: The average SBS value of IRCV without SB and bonded with MS was 18.95+7.80MPa and MS with SB was 19.30+ SB (4.85+2.12MPa and SADRC with SB (9.57+3.45MPa(p<0.05. Conclusion: increased SBS VIRK to enamel using MS resin cement than SADRC.  

  13. Cervical and incisal marginal discrepancy in ceramic laminate veneering materials: A SEM analysis

    Directory of Open Access Journals (Sweden)

    Hemalatha Ranganathan

    2017-01-01

    Full Text Available Context: Marginal discrepancy influenced by the choice of processing material used for the ceramic laminate veneers needs to be explored further for better clinical application. Aims: This study aimed to evaluate the amount of cervical and incisal marginal discrepancy associated with different ceramic laminate veneering materials. Settings and Design: This was an experimental, single-blinded, in vitro trial. Subjects and Methods: Ten central incisors were prepared for laminate veneers with 2 mm uniform reduction and heavy chamfer finish line. Ceramic laminate veneers fabricated over the prepared teeth using four different processing materials were categorized into four groups as Group I - aluminous porcelain veneers, Group II - lithium disilicate ceramic veneers, Group III - lithium disilicate-leucite-based veneers, Group IV - zirconia-based ceramic veneers. The cervical and incisal marginal discrepancy was measured using a scanning electron microscope. Statistical Analysis Used: ANOVA and post hoc Tukey honest significant difference (HSD tests were used for statistical analysis. Results: The cervical and incisal marginal discrepancy for four groups was Group I - 114.6 ± 4.3 μm, 132.5 ± 6.5 μm, Group II - 86.1 ± 6.3 μm, 105.4 ± 5.3 μm, Group III - 71.4 ± 4.4 μm, 91.3 ± 4.7 μm, and Group IV - 123.1 ± 4.1 μm, 142.0 ± 5.4 μm. ANOVA and post hoc Tukey HSD tests observed a statistically significant difference between the four test specimens with regard to cervical marginal discrepancy. The cervical and incisal marginal discrepancy scored F = 243.408, P < 0.001 and F = 180.844, P < 0.001, respectively. Conclusion: This study concluded veneers fabricated using leucite reinforced lithium disilicate exhibited the least marginal discrepancy followed by lithium disilicate ceramic, aluminous porcelain, and zirconia-based ceramics. The marginal discrepancy was more in the incisal region than in the cervical region in all the groups.

  14. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    International Nuclear Information System (INIS)

    Wananuruksawong, R; Jinawath, S; Wasanapiarnpong, T; Padipatvuthikul, P

    2011-01-01

    Silicon nitride (Si 3 N 4 ) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si 3 N 4 ceramic as a dental core material. The white Si 3 N 4 was prepared by pressureless sintering at relative low sintering temperature of 1650 deg. C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si 3 N 4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si 3 N 4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder ( 2 O 3 - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si 3 N 4 specimens, the firing was performed in electric tube furnace between 1000-1200 deg. C. The veneered specimens fired at 1100 deg. C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98x10 -6 deg. C -1 , rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  15. Randomized controlled split-mouth clinical trial of direct laminate veneers with two micro-hybrid resin composites

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, M.; Ozcan, Mutlu

    Objectives: This randomized, split-mouth clinical study evaluated the survival rate of direct laminate veneers made of two resin-composite materials. Methods: A total of 23 patients (mean age: 52.4 years old) received 96 direct composite laminate veneers using two micro-hybrid composites in

  16. Influence of cooling rate on residual stress profile in veneering ceramic: measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2011-09-01

    The manufacture of dental crowns and bridges generates residual stresses within the veneering ceramic and framework during the cooling process. Residual stress is an important factor that control the mechanical behavior of restorations. Knowing the stress distribution within the veneering ceramic as a function of depth can help the understanding of failures, particularly chipping, a well-known problem with Yttria-tetragonal-zirconia-polycrystal based fixed partial dentures. The objective of this study is to investigate the cooling rate dependence of the stress profile in veneering ceramic layered on metal and zirconia frameworks. The hole-drilling method, often used for engineering measurements, was adapted for use with veneering ceramic. The stress profile was measured in bilayered disc samples 20 mm in diameter, with a 0.7 mm thick metal or Yttria-tetragonal-zirconia-polycrystal framework and a 1.5mm thick veneering ceramic. Three different cooling procedures were investigated. The magnitude of the stresses in the surface of the veneering ceramic was found to increase with cooling rate, while the interior stresses decreased. At the surface, compressive stresses were observed in all samples. In the interior, compressive stresses were observed in metal samples and tensile in zirconia samples. Cooling rate influences the magnitude of residual stresses. These can significantly influence the mechanical behavior of metal-and zirconia-based bilayered systems. The framework material influenced the nature of the interior stresses, with zirconia samples showing a less favorable stress profile than metal. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Influence of firing time and framework thickness on veneered Y-TZP discs curvature.

    Science.gov (United States)

    Jakubowicz-Kohen, Boris D; Sadoun, Michaël J; Douillard, Thierry; Mainjot, Amélie K

    2014-02-01

    The objective of the present work was to study the curvature of very thinly, veneered Y-TZP discs of different framework thicknesses submitted to different firing times. Fifteen 20-mm-wide Y-TZP discs were produced in three different thicknesses: 0.75, 1, 1.5mm. One disc from each group was left unveneered while the others were layered with a 0.1mm veneering ceramic layer. All discs underwent five firing cycles for a total cumulative firing time of 30 min, 1, 2, 5 and 10h at 900°C. The curvature profile was measured using a profilometer after the veneering process and after each firing cycle respectively. A fitted curve was then used to estimate the, curvature radius. The coefficient of thermal expansion (CTE) measurements were taken on veneering, ceramic and Y-TZP beam samples that underwent the same firing schedule. Those data were used to calculate the curvature generated by CTE variations over firing time. All bilayered samples exhibited a curvature that increased over firing time inversely to framework thickness. However non-veneered samples did not exhibit any curvature modification. The results of the present study reveal that even a very thin veneer layer (0.1mm) can induce a significant curvature of Y-TZP discs. The dilatometric results showed that Tg and CTE, variations are not sufficient to explain this curvature. A chemical-induced zirconia volume, augmentation located at the framework sub-surface near the interface could explain the sample, curvature and its increase with firing time. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. [Effect of ceramic thickness and resin cement shades on final color of heat-pressed ceramic veneers].

    Science.gov (United States)

    Ren, D F; Zhan, K R; Chen, X D; Xing, W Z

    2017-02-09

    Objective: To analyze the effect of ceramic materials thickness and resin cement shades on the final color of ceramic veneers in the discolored teeth, and to investigate the color agreement of try-in pastes to the corresponding resin cements. Methods: Sixty artificial maxillary central incisor teeth (C2 shade) were used to simulate the natural discolored teeth and prepared according to veneer tooth preparation protocol. Veneers of different thickness in the body region (0.50 and 0.75 mm) were fabricated using ceramic materials (LT A2 shade, IPS e.max Press). The ceramic veneer specimens were bonded to the artificial teeth using the 6 shades of resin cements (Variolink Veneer: shades of LV-3, LV-2, HV+3; RelyX™ Veneer: shades of TR, A3, WO) ( n= 5). A clinical spectrophotometer was used to measure the color parameters of ceramic veneers at the cervical, body and incisal regions. Color changes of veneers before and after cementation were calculated and registered as ΔE1, and the changes between try-in paste and the corresponding resin cements were registered as ΔE2. Results: Three-way ANOVA indicated that ΔE1 and ΔE2 values were significantly affected by the ceramic thickness, resin cement shades and measuring regions ( Pceramic veneers were cemented with resin cements in shades of HV+3 and WO. The ΔE2 values of six shades ranged from 0.60-2.56. The shades of HV+3, WO and A3 resin cements were more than 1.60. Conclusions: Different thickness of ceramic materials, resin cement shades and measuring regions could affect the final color of ceramic veneers. The color differences of some resin cements and corresponding try-in pastes might be observed in clinical practice.

  19. Sintering of Si C by hot-pressing with addition of Al{sub 2}O{sub 3} and concentrate of rare earths; Sinterizacao por prensagem a quente com SiC com adicao de Al{sub 2}O{sub 3} e concentrado de terras raras

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, M.K.; Silva, C.R.M. [Centro Tecnico Aeroespacial (CTA-IAE), Sao Jose dos Campos, SP (Brazil). Inst. de Atividades Espaciais]. E-mail: miriamk@iae.cta.br; Nono, M.C.A.; Vieira, R.A. [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

    2004-07-01

    Silicon carbide (SiC) has essentially covalent bonds ({approx}88%). The high covalency bond is responsible for the good mechanical properties, although it induces a low self diffusion coefficient, making densification more difficult. For a successful densification is necessary to apply pressure on the samples, and/or the addition of sintering additives, which improves the densification. In this SiC samples with alumina (Al2O3) and concentrate of rare earth (CRE) addition were sintered by hot pressing in argon atmospheric at 20 MPa of pressure, heating rate of 20 deg C/min up to 1800 deg C and a dwell time of 1 h. Initially the CRE was calcined at 1000 deg C during 1 h. After that, three mixtures were prepared with distinct concentrations in high energy mill and the samples were sintered. The aim of this work is to improve SiC densification by the liquid phase formation during sintering owing to the additives reactions between itself. The pressure intensify the driving force for densification, taking the liquid phase to drain easier through the grain boundaries, making possible best accommodation and rearrangement of the grains. The application of the pressure on the samples during sintering contributes to improve densification and becomes possible sintering in lower temperature than conventional one. The phases of the sintered samples were analyzed by X-ray diffraction and the morphology were verified by scanning electron microscopy. (author)

  20. A Step-by-Step Conservative Approach for CAD-CAM Laminate Veneers

    Directory of Open Access Journals (Sweden)

    Gerardo Durán Ojeda

    2017-01-01

    Full Text Available The use of CAD/CAM technology has allowed the fabrication of ceramic restorations efficiently and with predictable results. Lithium disilicate is a type of glass ceramic material that can be used for the elaboration of laminate veneers, being monolithic restorations which require characterization through a covering ceramic in order to achieve acceptable esthetic results. The next case report shows a predictable clinical protocol for the rehabilitation of the anterior teeth through the preparation of CAD/CAM veneers (e.max CAD, Ivoclar Vivadent, Liechtenstein which have been characterized by a nanofluorapatite ceramic (e.max Ceram, Ivoclar Vivadent, Liechtenstein through the layering technique.

  1. Relative translucency of six all-ceramic systems. Part II: core and veneer materials.

    Science.gov (United States)

    Heffernan, Michael J; Aquilino, Steven A; Diaz-Arnold, Ana M; Haselton, Debra R; Stanford, Clark M; Vargas, Marcos A

    2002-07-01

    STATEMENT OF PROBLEM All-ceramic core materials with various strengthening compositions have a range of translucencies. It is unknown whether translucency differs when all-ceramic materials are fabricated similarly to the clinical restoration with a veneered core material. This study compared the translucency of 6 all-ceramic materials veneered and glazed at clinically appropriate thicknesses. Core specimens (n = 5 per group) of Empress dentin, Empress 2 dentin, In-Ceram Alumina, In-Ceram Spinell, In-Ceram Zirconia, and Procera AllCeram were fabricated as described in Part I of this study and veneered with their corresponding dentin porcelain to a final thickness of 1.47 +/- 0.01 mm. These specimens were compared with veneered Vitadur Alpha opaque dentin (as a standard), a clear glass disc (positive control), and a high-noble metal-ceramic alloy (Porc. 52 SF) veneered with Vitadur Omega dentin (negative control). Specimen reflectance was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Measurements were repeated after a glazing cycle. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white backing (Yw) to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (P<.05). Significant differences in contrast ratios were found among the ceramic systems tested when they were veneered (P<.0001) and after the glazing cycle (P<.0001). Significant changes in contrast ratios (P<.0001) also were identified when the veneered specimens were glazed. Within the limitations of this study, a range of translucency was identified in the veneered all-ceramic systems tested. Such variability may affect their ability to match natural teeth. The glazing cycle resulted

  2. Kubelka-Munk reflectance theory applied to porcelain veneer systems using a colorimeter.

    Science.gov (United States)

    Davis, B K; Johnston, W M; Saba, R F

    1994-01-01

    The purpose of this study was to demonstrate the ability of Kubelka-Munk reflectance theory to predict color parameters of veneer porcelain on various backings using colorimetric measurements. Tristimulus absorption and scattering coefficients were used to predict the respective tristimulus reflectance values of A1, D3, and translucent porcelain samples after they had been bonded to light and dark substrates using universal, opaque, and untinted shades of bonding resin. Observed and predicted reflectance values exhibited high correlation (r2 > or = 0.93 for each porcelain shade). Kubelka-Munk theory offers an accurate prediction for the resultant colorimetric reflectance parameters of veneer porcelain bonded to variously colored backings.

  3. Esthetic restorations of maxillary anterior teeth with orthodontic treatment and porcelain laminate veneers: a case report.

    Science.gov (United States)

    Moon, Ji-Eun; Kim, Sung-Hun; Han, Jung-Suk; Yang, Jae-Ho; Lee, Jai-Bong

    2010-06-01

    If orthodontists and restorative dentists establish the interdisciplinary approach to esthetic dentistry, the esthetic and functional outcome of their combined efforts will be greatly enhanced. This article describes satisfying esthetic results obtained by the distribution of space for restoration by orthodontic treatment and porcelain laminate veneers in uneven space between maxillary anterior teeth. It is proposed that the use of orthodontic treatment for re-distribution of the space and the use of porcelain laminate veneers to alter crown anatomy provide maximum esthetic and functional correction for patients with irregular interdental spacing.

  4. Thermal Expansion Behavior of Hot-Pressed Engineered Matrices

    Science.gov (United States)

    Raj, S. V.

    2016-01-01

    Advanced engineered matrix composites (EMCs) require that the coefficient of thermal expansion (CTE) of the engineered matrix (EM) matches those of the fiber reinforcements as closely as possible in order to reduce thermal compatibility strains during heating and cooling of the composites. The present paper proposes a general concept for designing suitable matrices for long fiber reinforced composites using a rule of mixtures (ROM) approach to minimize the global differences in the thermal expansion mismatches between the fibers and the engineered matrix. Proof-of-concept studies were conducted to demonstrate the validity of the concept.

  5. Structure and properties of hot-pressed boron carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Koval' chenko, M S; Tkachenko, IU G; Koval' chuk, V V; Iurchenko, D Z; Satanin, S V [Institut Problem Materialovedeniia, Kiev (Ukrainian SSR)

    1990-07-01

    The microstructure and strength of B4C-TiB2-TiO{sub 2} ceramics samples, hot-compacted from a mixture of two types of B4C-TiO2-C powder, are examined. The two types are obtained by combining boric acid with either sucrose or carbon black. The grain-sizes of the two powders are found to be distinctly different from one another both before and after the grinding procedure and the degree of dispersion is not high. The strength tests show 600 MPa, the Vicker's hardness is 34.5 GPa, and the crack resistance coefficient of ceramics containing 15 percent TiB2 by mass is 5 MPa m exp 1/2. The use of soluble boron carbide powder helps achieve higher levels of strength and crack resistance. 5 refs.

  6. Raman spectra of hot-pressed boron suboxide

    CSIR Research Space (South Africa)

    Machaka, R

    2011-01-01

    Full Text Available on in- situ/online measurements (such as GIXRD, Raman Spectroscopy, FIB- Electron Microscopy) during (i) ion implantation, (ii) PLD growth of nanoparticles SW/MW-CNTs, oxide semiconductor multi-layer, metal/Si and metal/metal systems. Moreover, He...], aluminium magnesium boride ? AlMgB14 [8], and the newly synthesized boron subnitride ? B13N2 [9, 10]. With hardness values reported between 24 GPa and 45 GPa [7, 11, 12], B6O is sometimes considered to be the third hardest material only after diamond...

  7. Influence of abutment type and esthetic veneering on preload maintenance of abutment screw of implant-supported crowns.

    Science.gov (United States)

    Delben, Juliana Aparecida; Barão, Valentim Adelino Ricardo; Dos Santos, Paulo Henrique; Assunção, Wirley Gonçalves

    2014-02-01

    The effect of veneering materials on screw joint stability remains inconclusive. Thus, this study evaluated the preload maintenance of abutment screws of single crowns fabricated with different abutments and veneering materials. Sixty crowns were divided into five groups (n = 12): UCLA abutment in gold alloy with ceramic (group GC) and resin (group GR) veneering, UCLA abutment in titanium with ceramic (group TiC) and resin (group TiR) veneering, and zirconia abutment with ceramic veneering (group ZiC). Abutment screws made of gold were used with a 35 Ncm insertion torque. Detorque measurements were obtained initially and after mechanical cycling. Data were analyzed by ANOVA and Fisher's exact test at a significance level of 5%. For the initial detorque means (in Ncm), group TiC (21.4 ± 1.78) exhibited statistically lower torque maintenance than groups GC (23.9 ± 0.91), GR (24.1 ± 1.34), and TiR (23.2 ± 1.33) (p abutment type and veneering material. More irregular surfaces in the hexagon area of the castable abutments were observed. The superiority of any veneering material concerning preload maintenance was not established. © 2013 by the American College of Prosthodontists.

  8. Role of core support material in veneer failure of brittle layer structures.

    Science.gov (United States)

    Hermann, Ilja; Bhowmick, Sanjit; Lawn, Brian R

    2007-07-01

    A study is made of veneer failure by cracking in all-ceramic crown-like layer structures. Model trilayers consisting of a 1 mm thick external glass layer (veneer) joined to a 0.5 mm thick inner stiff and hard ceramic support layer (core) by epoxy bonding or by fusion are fabricated for testing. The resulting bilayers are then glued to a thick compliant polycarbonate slab to simulate a dentin base. The specimens are subjected to cyclic contact (occlusal) loading with spherical indenters in an aqueous environment. Video cameras are used to record the fracture evolution in the transparent glass layer in situ during testing. The dominant failure mode is cone cracking in the glass veneer by traditional outer (Hertzian) cone cracks at higher contact loads and by inner (hydraulically pumped) cone cracks at lower loads. Failure is deemed to occur when one of these cracks reaches the veneer/core interface. The advantages and disadvantages of the alumina and zirconia core materials are discussed in terms of mechanical properties-strength and toughness, as well as stiffness. Consideration is also given to the roles of interface strength and residual thermal expansion mismatch stresses in relation to the different joining methods. Copyright 2006 Wiley Periodicals, Inc.

  9. Ceramic Veneers and Direct-Composite Cases of Amelogenesis Imperfecta Rehabilitation.

    Science.gov (United States)

    Shibata, S; Taguchi, Cmc; Gondo, R; Stolf, S C; Baratieri, L N

    2016-01-01

    The aim of this article is to present two case reports for the treatment of patients affected with amelogenesis imperfecta. One case was treated with composite resin and the other case with ceramic veneers. Esthetic and functional results were achieved using both treatments, and a review of advantages and disadvantages is presented.

  10. Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains.

    Directory of Open Access Journals (Sweden)

    Jie Min

    Full Text Available The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains.Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated.The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes.Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings.

  11. Esthetic Rehabilitation of Anterior Teeth with Porcelain Laminates and Sectional Veneers

    NARCIS (Netherlands)

    Gresnigt, Marco; Ozcan, Mutlu

    2011-01-01

    Full-coverage bonded porcelain restorations offer predictable treatment options in dentistry, but a certain amount of tooth material must be removed to allow space for the required thickness of the restorative material. Laminate veneers and inlays are considered minimally invasive, but they also

  12. Illuminating light-dependent color shifts in core and veneer layers of dental all-ceramics

    Science.gov (United States)

    Lee, Yong-Keun; Cha, Hyun-Suk; Yu, Bin

    2014-09-01

    The color of an object is perceived differently depending on the ambient light conditions. Since dental all-ceramic restorations are fabricated by building up several layers to reproduce the tooth shade, the optical properties of each layer should be optimized for successful shade reproduction. This study aimed to determine the separate contributions of the color shifts in each of the core and veneer layers of all-ceramics by switching the illuminating lights on the color shifts of layered ceramics. Specimens of seven kinds of core ceramics and the corresponding veneer ceramics for each core were fabricated with a layered thickness of 1.5 mm. A sintering ceramic was used as a reference core material. The Commission Internationale de l'Eclairage (CIE) color coordinates of core, veneer, and layered specimens were measured with a spectroradiometer under the CIE illuminant D65 (daylight), A (incandescent lamp), and F9 (fluorescent lamp) simulating lights. Color shifts of the layered specimens were primarily determined by the CIE a* shifts (D65 to A switch) or by the CIE b* shifts (D65 to F9 switch) of the veneer layer. The color coordinates shifts in the constituent layers differentially influenced those of the layered specimens by the kind of switched lights. Therefore, the optical properties of the constituent layers of all-ceramics should be controlled to reflect these findings.

  13. Hardwood Face Veneer and Plywood Mill Closures in Michigan and Wisconsin Since 1950

    Science.gov (United States)

    Lewis T. Hendricks

    1966-01-01

    In recent years there has been a great deal of concern about the closure of numberous hardwood face veneer and plywood mills in Michigan and Wisconsin. As part of an overall study of that industry in the northern Lake States region, the basic reasons leading to the closure of these mills were investigated. In the past 15 years, there have been eight known mill...

  14. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    Science.gov (United States)

    Wananuruksawong, R.; Jinawath, S.; Padipatvuthikul, P.; Wasanapiarnpong, T.

    2011-10-01

    Silicon nitride (Si3N4) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si3N4 ceramic as a dental core material. The white Si3N4 was prepared by pressureless sintering at relative low sintering temperature of 1650 °C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si3N4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si3N4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (tube furnace between 1000-1200°C. The veneered specimens fired at 1100°C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98×10-6 °C-1, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  15. Effects of particles thickness and veneer reiforced layer in the properties of oriented strand boards OSB

    Directory of Open Access Journals (Sweden)

    Setsuo Iwakiri

    2009-03-01

    Full Text Available This work evaluated the effects of particle thickness and veneer reinforced layer on the physical and mechanicalproperties of OSB made of Pinus taeda L. The boards were manufactured with particle thickness of 0.4, 0.7 and 1.0 mm and phenolformaldehyderesin in the proportion of 6% of solid content. To the veneer reinforced layer was used veneer from Pinus taeda with 2.0mm of thickness. The increase in the slenderness (length/thickness ratio of thins particles, results in the higher values of MOE andMOR in the cross direction. The increase in the particles thickness contributed to higher values of the board internal bond. Thedifferent particles thickness did not clearly affected on the physical properties of OSB. The veneer reinforced layer results in the higheraverage values of MOE and MOR in the cross direction. All of the results of MOE and MOR obtained for boards with differentthickness attend tominimum values required per CSA 0437 (CSA, 1993. For the internal bond, the results were satisfactory to boardsmanufactured with particles thickness of 0.7 and 1.0 mm. According to the results the main conclusions were: (i The increase in theparticles thickness contributed to lower values of MOE and MOR, and higher values of the board internal bond; (ii the veneerreinforced layer increased MOE and MOR values in the cross direction.

  16. Color management of porcelain veneers: influence of dentin and resin cement colors

    NARCIS (Netherlands)

    Dozic, A.; Tsagkari, M.; Khashayar, G.; Aboushelib, M.

    2010-01-01

    Objective: Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence

  17. ESTIMATING THE SIZE OF LATE VENEER IMPACTORS FROM IMPACT-INDUCED MIXING ON MERCURY

    International Nuclear Information System (INIS)

    Rivera-Valentin, E. G.; Barr, A. C.

    2014-01-01

    Late accretion of a ''veneer'' of compositionally diverse planetesimals may introduce chemical heterogeneity in the mantles of the terrestrial planets. The size of the late veneer objects is an important control on the angular momenta, eccentricities, and inclinations of the terrestrial planets, but current estimates range from meter-scale bodies to objects with diameters of thousands of kilometers. We use a three-dimensional global Monte Carlo model of impact cratering, excavation, and ejecta blanket formation to show that evidence of mantle heterogeneity can be preserved within ejecta blankets of mantle-exhuming impacts on terrestrial planets. Compositionally distinct provinces implanted at the time of the late veneer are most likely to be preserved in bodies whose subsequent geodynamical evolution is limited. Mercury may have avoided intensive mixing by solid-state convection during much of its history. Its subsequent bombardment may have then excavated evidence of primordial mantle heterogeneity introduced by the late veneer. Simple geometric arguments can predict the amount of mantle material in the ejecta blanket of mantle-exhuming impacts, and deviations in composition relative to geometric predictions can constrain the length-scale of chemical heterogeneities in the subsurface. A marked change in the relationship between mantle and ejecta composition occurs when chemically distinct provinces are ∼250 km in diameter; thus, evidence of bombardment by thousand-kilometer-sized objects should be readily apparent from the variation in compositions of ejecta blankets in Mercury's ancient cratered terrains

  18. Influence of thermal expansion mismatch on residual stress profile in veneering ceramic layered on zirconia: Measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Najjar, Achref; Jakubowicz-Kohen, Boris D; Sadoun, Michaël J

    2015-09-01

    Mismatch in thermal expansion coefficient between core and veneering ceramic (Δα=αcore-αveneer, ppm/°C) is reported as a crucial parameter influencing veneer fractures with Yttria-tetragonal-zirconia-polycrystal (Y-TZP) prostheses, which still constitutes a misunderstood problem. However, the common positive Δα concept remains empirical. The objective of this study is to investigate the Δα dependence of residual stress profiles in veneering ceramic layered on Y-TZP frameworks. The stress profile was measured with the hole-drilling method in bilayered disc samples of 20mm diameter with a 0.7mm thick Y-TZP framework and a 1.5mm thick veneer layer. 3 commercial and 4 experimental veneering ceramics (n=3 per group) were used to obtain different Δα varying from -1.3ppm/°C to +3.2ppm/°C, which were determined by dilatometric analyses. Veneer fractures were observed in samples with Δα≥+2.3 or ≤-0.3ppm/°C. Residual stress profiles measured in other groups showed compressive stresses in the surface, these stresses decreasing with depth and then becoming more compressive again near the interface. Small Δα variations were shown to induce significant changes in residual stress profiles. Compressive stress near the framework was found to decrease inversely to Δα. Veneer CTE close to Y-TZP (+0.2ppm/°C Δα) gived the most favorable stress profile. Yet, near the framework, Δα-induced residual stress varied inversely to predictions. This could be explained by the hypothesis of structural changes occurrence within the Y-TZP surface. Consequently, the optimum Δα value cannot be determined before understanding Y-TZP's particular behavior when veneered. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. Interfacial characterization of ceramic core materials with veneering porcelain for all-ceramic bi-layered restorative systems.

    Science.gov (United States)

    Tagmatarchis, Alexander; Tripodakis, Aris-Petros; Filippatos, Gerasimos; Zinelis, Spiros; Eliades, George

    2014-01-01

    The aim of the study was to characterize the elemental distribution at the interface between all-ceramic core and veneering porcelain materials. Three groups of all-ceramic cores were selected: A) Glass-ceramics (Cergo, IPS Empress, IPS Empress 2, e-max Press, Finesse); B) Glass-infiltrated ceramics (Celay Alumina, Celay Zirconia) and C) Densely sintered ceramics (Cercon, Procera Alumina, ZirCAD, Noritake Zirconia). The cores were combined with compatible veneering porcelains and three flat square test specimens were produced for each system. The core-veneer interfaces were examined by scanning electron microscopy and energy dispersive x-ray microanalysis. The glass-ceramic systems showed interfacial zones reach in Si and O, with the presence of K, Ca, Al in core and Ca, Ce, Na, Mg or Al in veneer material, depending on the system tested. IPS Empress and IPS Empress 2 demonstrated distinct transitional phases at the core-veneer interface. In the glassinfiltrated systems, intermixing of core (Ce, La) with veneer (Na, Si) elements occurred, whereas an abrupt drop of the core-veneer elemental concentration was documented at the interfaces of all densely sintered ceramics. The results of the study provided no evidence of elemental interdiffusion at the core-veneer interfaces in densely sintered ceramics, which implies lack of primary chemical bonding. For the glass-containing systems (glassceramics and glass-infiltrated ceramics) interdiffusion of the glass-phase seems to play a critical role in establishing a primary bonding condition between ceramic core and veneering porcelain.

  20. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    Energy Technology Data Exchange (ETDEWEB)

    Wananuruksawong, R; Jinawath, S; Wasanapiarnpong, T [Research Unit of Advanced Ceramic, Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok (Thailand); Padipatvuthikul, P, E-mail: raayaa_chula@hotmail.com [Faculty of Dentistry, Srinakharinwirot University, Bangkok (Thailand)

    2011-10-29

    Silicon nitride (Si{sub 3}N{sub 4}) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si{sub 3}N{sub 4} ceramic as a dental core material. The white Si{sub 3}N{sub 4} was prepared by pressureless sintering at relative low sintering temperature of 1650 deg. C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si{sub 3}N{sub 4} ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si{sub 3}N{sub 4} specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (<150 micrometer, Pyrex) with 5 wt% of zirconia powder (3 wt% Y{sub 2}O{sub 3} - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si{sub 3}N{sub 4} specimens, the firing was performed in electric tube furnace between 1000-1200 deg. C. The veneered specimens fired at 1100 deg. C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98x10{sup -6} deg. C{sup -1}, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  1. [The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

    Science.gov (United States)

    Jiang, Jie; Zhang, Xin; Gao, Mei-qin; Zhang, Fei-min; Lu, Xiao-li

    2015-06-01

    To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

  2. The influence of felling season and log-soaking temperature on the wetting and phenol formaldehyde adhesive bonding characteristics of birch veneer

    Science.gov (United States)

    Anti Rohumaa; Christopher G. Hunt; Charles R. Frihart; Pekka Saranpää; Martin Ohlmeyer; Mark Hughes

    2014-01-01

    Most adhesive studies employing wood veneer as the substrate assume that it is a relatively uniform material if wood species and veneer thickness are constant. In the present study, veneers from rotary cut birch (Betula pendula Roth) were produced from logs harvested in spring, autumn and winter, and soaked at 20°C and 70°C prior to peeling. Firstly...

  3. Esthetic, occlusal, and periodontal rehabilitation of anterior teeth with minimum thickness porcelain laminate veneers.

    Science.gov (United States)

    da Cunha, Leonardo Fernandes; Pedroche, Lorena Oliveira; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

    2014-12-01

    Ceramic veneers of minimum thickness provide satisfactory esthetic outcomes while preserving the dental structure. Dental ceramics can both improve the esthetic appearance and reestablish the strength and function of teeth. In worn anterior teeth, functional surfaces, for example, anterior and lateral guidance, can be restored effectively. The characteristics of dental ceramics, such as color stability and mechanical and optical properties, make this material a good choice for indirect restorations, especially when optimum function and esthetics are required. This clinical report presents an occlusal, periodontal, and restorative solution with minimum thickness glass ceramic veneers for worn anterior teeth with multiple diastemas. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Aesthetic composite veneers for an adult patient with amelogenesis imperfecta: a case report.

    Science.gov (United States)

    Brignall, Ian; Mehta, Shamir B; Banerji, Subir; Millar, Brian J

    2011-11-01

    This case has been presented as part of the continual assessment requirement for the MSc in Aesthetic Dentistry, King's College Dental Institute. Amelogenesis imperfecta (AI) is a hereditary disorder of enamel formation, affecting both the permanent and deciduous dentitions. It can be classified into hypoplastic, hypomaturation and hypocalcified types and presents with different hereditary patterns. The aim of this article is to provide an overview of amelogenesis imperfecta, including a detailed case report for an aesthetically concerned adult patient presenting in general practice with a Witkop's Type IA defect managed with the placement of direct, layered resin composite veneers. Amelogenesis imperfecta patients are susceptible to the restorative cycle of replacement restorations like any other patient, but start with a distinct disadvantage.This case report demonstrates a minimally invasive, relatively simple and cost-effective option for the aesthetic correction of a case of hypoplastic amelogenesis imperfecta with layered composite veneers. Dent Update 2011; 38:594-603

  5. Viscoelastic finite element analysis of residual stresses in porcelain-veneered zirconia dental crowns.

    Science.gov (United States)

    Kim, Jeongho; Dhital, Sukirti; Zhivago, Paul; Kaizer, Marina R; Zhang, Yu

    2018-06-01

    The main problem of porcelain-veneered zirconia (PVZ) dental restorations is chipping and delamination of veneering porcelain owing to the development of deleterious residual stresses during the cooling phase of veneer firing. The aim of this study is to elucidate the effects of cooling rate, thermal contraction coefficient and elastic modulus on residual stresses developed in PVZ dental crowns using viscoelastic finite element methods (VFEM). A three-dimensional VFEM model has been developed to predict residual stresses in PVZ structures using ABAQUS finite element software and user subroutines. First, the newly established model was validated with experimentally measured residual stress profiles using Vickers indentation on flat PVZ specimens. An excellent agreement between the model prediction and experimental data was found. Then, the model was used to predict residual stresses in more complex anatomically-correct crown systems. Two PVZ crown systems with different thermal contraction coefficients and porcelain moduli were studied: VM9/Y-TZP and LAVA/Y-TZP. A sequential dual-step finite element analysis was performed: heat transfer analysis and viscoelastic stress analysis. Controlled and bench convection cooling rates were simulated by applying different convective heat transfer coefficients 1.7E-5 W/mm 2 °C (controlled cooling) and 0.6E-4 W/mm 2 °C (bench cooling) on the crown surfaces exposed to the air. Rigorous viscoelastic finite element analysis revealed that controlled cooling results in lower maximum stresses in both veneer and core layers for the two PVZ systems relative to bench cooling. Better compatibility of thermal contraction coefficients between porcelain and zirconia and a lower porcelain modulus reduce residual stresses in both layers. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Automated knot detection with visual post-processing of Douglas-fir veneer images

    Science.gov (United States)

    C.L. Todoroki; Eini C. Lowell; Dennis Dykstra

    2010-01-01

    Knots on digital images of 51 full veneer sheets, obtained from nine peeler blocks crosscut from two 35-foot (10.7 m) long logs and one 18-foot (5.5 m) log from a single Douglas-fir tree, were detected using a two-phase algorithm. The algorithm was developed using one image, the Development Sheet, refined on five other images, the Training Sheets, and then applied to...

  7. Effect of Provisional Cements on Shear Bond Strength of Porcelain Laminate Veneers

    OpenAIRE

    Altintas, Subutay Han; Tak, Onjen; Secilmis, Asli; Usumez, Aslihan

    2011-01-01

    Objectives: The purpose of this study was to evaluate the effect of three provisional cements and two cleaning techniques on the final bond strength of porcelain laminate veneers. Methods: The occlusal third of the crowns of forty molar teeth were sectioned and embedded in autopolymerizing acrylic resin. Dentin surfaces were polished and specimens were randomly divided into four groups (n=10). Provisional restorations were fabricated and two provisional restorations were cemented onto each to...

  8. Three-unit posterior zirconia-ceramic fixed dental prostheses (FDPs) veneered with layered and milled (CAD-on) veneering ceramics: 1-year follow-up of a randomized controlled clinical trial.

    Science.gov (United States)

    Grohmann, Philipp; Bindl, Andreas; Hämmerle, Christoph; Mehl, Albert; Sailer, Irena

    2015-01-01

    The aim of this multicenter randomized controlled clinical trial was to test posterior zirconia-ceramic fixed dental prostheses (FDPs) veneered with a computer-aided design/computer- assisted manufacture (CAD/CAM) lithium disilicate veneering ceramic (CAD-on) and manually layered zirconia veneering ceramic with respect to survival of the FDPs, and technical and biologic outcomes. Sixty patients in need of one posterior three-unit FDP were included. The zirconia frameworks were produced with a CAD/CAM system (Cerec inLab 3D/Cerec inEOS inLab). Thirty FDPs were veneered with a CAD/CAM lithium disilicate veneering ceramic (Cad-on) (test) and 30 were veneered with a layered zirconia veneering ceramic (control). For the clinical evaluation at baseline, 6, and 12 months, the United States Public Health Service (USPHS) criteria were used. The biologic outcome was judged by comparing the plaque control record (PCR), bleeding on probing (BOP), and probing pocket depth (PPD). Data were statistically analyzed. Fifty-six patients were examined at a mean follow-up of 13.9 months. At the 1-year follow-up the survival rate was 100% in the test and in the control group. No significant differences of the technical outcomes occurred. Major chipping occurred in the control group (n = 3) and predominantly minor chipping in the test group (minor n = 2, major n = 1). No biologic problems or differences were found. Both types of zirconia-ceramic FDPs exhibited very good clinical outcomes without differences between groups. Chipping occurred in both types of FDPs at small amounts, yet the extension of the chippings differed. The test FDPs predominantly exhibited minor chipping, the control FDPs major chipping.

  9. Equilibrium moisture content of OSB panels produced with veneer inclusion and different types of adhesive

    Directory of Open Access Journals (Sweden)

    Lourival Marin Mendes

    2014-03-01

    Full Text Available The aim of this study was to evaluate different statistical models to estimate the equilibrium moisture content of OSB panels exposed to different conditions of air temperature and relative humidity, And also to evaluate the influence of the adhesive and veneer inclusion in the equilibrium moisture content. The panels were produced with three different adhesive types (phenol-formaldehyde - FF, melamine-urea-formaldehyde - MUF, and phenol-melamine-urea-formaldehyde - PMUF and with and without veneer inclusion. The evaluation of the equilibrium moisture content of the panels was carried out at temperatures of 30, 40 and 50°C and relative humidity of 40, 50, 60, 70, 80 and 90%. The modeling of equilibrium moisture content was performed using the statistical non-linear and polynomial models. In general, the polynomial models are most indicated for determining the equilibrium moisture content of OSB. The models adjusted only with air relative humidity presented the best precision measurements. The type of adhesive affected the equilibrium moisture content of the panels, being observed for adhesives PMUF and FF the same trend of variation, and the highest values obtained for the panels produced with adhesive MUF. The veneer inclusion decreased the equilibrium moisture content only in the panels with MUF adhesive.

  10. [Interface bond and compatibility between GI-II glass/alumina composite and Vitadur alpha veneering porcelain].

    Science.gov (United States)

    Meng, Yukun; Chao, Yonglie; Liao, Yunmao

    2002-01-01

    Multiple layer techniques were commonly employed in fabricating all-ceramic restorations. Bond and compatibility between layers were vitally important for the clinical success of the restorations. The purposes of this study were to investigate the bond of the interface between the GI-II glass/alumina composite and Vitadur alpha veneering porcelain, and to study the thermal compatibility between them. Prepared a bar shaped specimen of GI-II glass/alumina composite 25 mm x 5 mm x 1 mm in size, with bottom surface pre-notched. The upper surface was veneered with Vitadur alpha veneering porcelain (0.2 mm opaque dentin and 0.6 mm dentin porcelain), then fractured and the fracture surface were examined under scanning electron microscope (SEM) and electron microprobe analyzer (EMPA) with electron beam of 10 micrometer in diameter; ten all-ceramic single crowns for an upper right central incisor were fabricated and the temperatures of thermal shock resistance were tested. SEM observation showed tight bond between the composite and the porcelain; The results of EMPA showed that penetration of Na, Al elements from glass/alumina into veneering porcelain and Si, K, Ca elements from veneering porcelain into glass/alumina occurred after sintering baking; The temperature of thermal shock resistance for anterior crowns in this study was 158 +/- 10.3 degrees C, cracks were mainly distributed in veneering porcelain with thicker layer. Chemical bond exists between the GI-II glass/alumina composite and Vitadur alpha veneering porcelain, and there is good thermal compatibility between them.

  11. Veneered zirconia inlay-retained fixed dental prostheses: 10-Year results from a prospective clinical study.

    Science.gov (United States)

    Rathmann, Friederike; Bömicke, Wolfgang; Rammelsberg, Peter; Ohlmann, Brigitte

    2017-09-01

    The purpose of this study was to evaluate the 10-year clinical performance of zirconia-based inlay-retained fixed dental prostheses (IRFDP). For replacement of a molar in 27 patients, 30 IRFDP were luted by use of different cements, Panavia F (Kuraray Europe GmbH) or Multilink Automix (Ivoclar Vivadent GmbH), with use of inlay/inlay, inlay/full-crown, or inlay/partial-crown retainers for anchorage. Frameworks were milled from yttria-stabilized zirconia (IPS e.maxZirCAD; Ivoclar Vivadent GmbH) and fully veneered with pressable ceramic (IPS e.max ZirPress; Ivoclar Vivadent GmbH). Before luting, the IRFDP were silica-coated (Rocatec; 3M Espe) and silanized (Monobond S; Ivoclar Vivadent GmbH). Complications (for example, chipping or delamination of the veneering ceramic, debonding, secondary caries, endodontic treatment, and abutment tooth fracture) and failure were reported, by use of standardized report forms, 2 weeks, 6 months, and 1, 2, and 10 years after cementation. Statistical analysis included Kaplan-Meier survival and success (complication-free survival) and Cox regression analysis (α=0.05 for all). During the 10-year observation period, the complications most often observed were chipping of the veneer and debonding. Twenty-five restorations failed and one participant dropped out. Cumulative 10-year survival and success were 12.1% and 0%, respectively. The design of the retainer, use of a dental dam, choice of cement, and location in the dental arch had no statistically significant effect on the occurrence of complications. Use of fully veneered zirconia-based IRFDP with this technique cannot be recommended. A large incidence of complications and poor survival were observed for fully veneered zirconia-based IRFDP, revealing an urgent need for further design improvements for this type of restoration. This, again, emphasizes the need for testing of new restoration designs in clinical trials before implementation in general dental practice. Copyright © 2017

  12. Effect of various veneering techniques on mechanical strength of computer-controlled zirconia framework designs.

    Science.gov (United States)

    Kanat, Burcu; Cömlekoğlu, Erhan M; Dündar-Çömlekoğlu, Mine; Hakan Sen, Bilge; Ozcan, Mutlu; Ali Güngör, Mehmet

    2014-08-01

    The objectives of this study were to evaluate the fracture resistance (FR), flexural strength (FS), and shear bond strength (SBS) of zirconia framework material veneered with different methods and to assess the stress distributions using finite element analysis (FEA). Zirconia frameworks fabricated in the forms of crowns for FR, bars for FS, and disks for SBS (N = 90, n = 10) were veneered with either (a) file splitting (CAD-on) (CD), (b) layering (L), or (c) overpressing (P) methods. For crown specimens, stainless steel dies (N = 30; 1 mm chamfer) were scanned using the labside contrast spray. A bilayered design was produced for CD, whereas a reduced design (1 mm) was used for L and P to support the veneer by computer-aided design and manufacturing. For bar (1.5 × 5 × 25 mm(3) ) and disk (2.5 mm diameter, 2.5 mm height) specimens, zirconia blocks were sectioned under water cooling with a low-speed diamond saw and sintered. To prepare the suprastructures in the appropriate shapes for the three mechanical tests, nano-fluorapatite ceramic was layered and fired for L, fluorapatite-ceramic was pressed for P, and the milled lithium-disilicate ceramics were fused with zirconia by a thixotropic glass ceramic for CD and then sintered for crystallization of veneering ceramic. Crowns were then cemented to the metal dies. All specimens were stored at 37°C, 100% humidity for 48 hours. Mechanical tests were performed, and data were statistically analyzed (ANOVA, Tukey's, α = 0.05). Stereomicroscopy and scanning electron microscopy (SEM) were used to evaluate the failure modes and surface structure. FEA modeling of the crowns was obtained. Mean FR values (N ± SD) of CD (4408 ± 608) and L (4323 ± 462) were higher than P (2507 ± 594) (p mechanical tests, whereas a layering technique increased the FR when an anatomical core design was employed. File splitting (CAD-on) or layering veneering ceramic on zirconia with a reduced framework design may reduce ceramic chipping

  13. Effectiveness of optical illusions 
applied on a single composite resin veneer for the diastema closure 
of maxillary central incisors.

    Science.gov (United States)

    Katsarou, Thomai; Antoniadou, Maria; Papazoglou, Efstratios

    To assess the esthetic effectiveness of four illusion techniques applied to a composite resin veneer for diastema closure between maxillary central incisors. An acrylic model with six natural maxillary anterior teeth was fabricated with a 2-mm diastema between the central incisors. Resin veneers were constructed on the left central incisor and the following cases were derived: V0: no veneer; V1: veneer without optical illusion features; V2: veneer with centralized interproximal ridges; V3: veneer with curved incisal edges; V4: veneer with gray pigment mesially/distally; V5: veneer with gray pigment on the developmental lobes. Digital printed photos of the models (13.2 x 17.8 cm, and 6.1 x 8 cm), with low, medium, and high smile lines and without a smile line (processed by Adobe Photoshop CS6) were shown to three groups of people (faculty members, senior undergraduate students, and patients; n = 25/group) for them to assess the overall size and width of the two central incisors. The results were analyzed by Pearson's and chi-square goodness of fit tests. There was no significant influence in the estimation of the two central incisors as being the same size, according to the technique used (P = 0.869) and group of evaluators (P = 0.209). The estimated probability of assessing the tested incisor as wider was indicatively lower in V2 compared to V1 (adjusted odds ratio = 0.59; P = 0.088). The height of the smile line affected the evaluation of the veneers only in the large-sized photos. No interference is the best esthetic decision concerning a 2-mm diastema closure when restoring only one central incisor with a laminate veneer. The next best option is to deliver a veneer with centralized interproximal ridges.

  14. Influence of Different Types of Resin Luting Agents on Color Stability of Ceramic Laminate Veneers Subjected to Accelerated Artificial Aging.

    Science.gov (United States)

    Silami, Francisca Daniele Jardilino; Tonani, Rafaella; Alandia-Román, Carla Cecilia; Pires-de-Souza, Fernanda de Carvalho Panzeri

    2016-01-01

    The aim of this study was to evaluate the influence of accelerated aging (AAA) on the color stability of resin cements for bonding ceramic laminate veneers of different thicknesses. The occlusal surfaces of 80 healthy human molars were flattened. Ceramic laminate veneers (IPS e-max Ceram) of two thicknesses (0.5 and 1.0 mm) were bonded with three types of luting agents: light-cured, conventional dual and self-adhesive dual cement. Teeth without restorations and cement samples (0.5 mm) were used as control. After initial color evaluations, the samples were subjected to AAA for 580 h. After this, new color readouts were made, and the color stability (ΔE) and luminosity (ΔL) data were analyzed. The greatest color changes (p<0.05) occurred when 0.5 mm veneers were fixed with light-cured cement and the lowest when 1.0 mm veneers were fixed with conventional dual cement. There was no influence of the restoration thickness when the self-adhesive dual cement was used. When veneers were compared with the control groups, it was verified that the cement samples presented the greatest alterations (p<0.05) in comparison with both substrates and restored teeth. Therefore, it was concluded that the thickness of the restoration influences color and luminosity changes for conventional dual and light-cured cements. The changes in self-adhesive cement do not depend on restoration thickness.

  15. Oregon's forest products industry: 1994.

    Science.gov (United States)

    Franklin R. Ward

    1997-01-01

    This report presents the findings of a survey of primary forest products industries in Oregon for 1994. The survey included the following sectors: lumber; veneer; pulp and board; shake and shingle; export; and post, pole, and piling. Tables, presented by sector and for the industry as a whole, include characteristics of the industry, nature and flow of logs consumed,...

  16. Reliability and failure modes of implant-supported zirconium-oxide fixed dental prostheses related to veneering techniques

    Science.gov (United States)

    Baldassarri, Marta; Zhang, Yu; Thompson, Van P.; Rekow, Elizabeth D.; Stappert, Christian F. J.

    2011-01-01

    Summary Objectives To compare fatigue failure modes and reliability of hand-veneered and over-pressed implant-supported three-unit zirconium-oxide fixed-dental-prostheses(FDPs). Methods Sixty-four custom-made zirconium-oxide abutments (n=32/group) and thirty-two zirconium-oxide FDP-frameworks were CAD/CAM manufactured. Frameworks were veneered with hand-built up or over-pressed porcelain (n=16/group). Step-stress-accelerated-life-testing (SSALT) was performed in water applying a distributed contact load at the buccal cusp-pontic-area. Post failure examinations were carried out using optical (polarized-reflected-light) and scanning electron microscopy (SEM) to visualize crack propagation and failure modes. Reliability was compared using cumulative-damage step-stress analysis (Alta-7-Pro, Reliasoft). Results Crack propagation was observed in the veneering porcelain during fatigue. The majority of zirconium-oxide FDPs demonstrated porcelain chipping as the dominant failure mode. Nevertheless, fracture of the zirconium-oxide frameworks was also observed. Over-pressed FDPs failed earlier at a mean failure load of 696 ± 149 N relative to hand-veneered at 882 ± 61 N (profile I). Weibull-stress-number of cycles-unreliability-curves were generated. The reliability (2-sided at 90% confidence bounds) for a 400N load at 100K cycles indicated values of 0.84 (0.98-0.24) for the hand-veneered FDPs and 0.50 (0.82-0.09) for their over-pressed counterparts. Conclusions Both zirconium-oxide FDP systems were resistant under accelerated-life-time-testing. Over-pressed specimens were more susceptible to fatigue loading with earlier veneer chipping. PMID:21557985

  17. The effect of veneering and heat treatment on the flexural strength of Empress 2 ceramics.

    Science.gov (United States)

    Cattell, M J; Palumbo, R P; Knowles, J C; Clarke, R L; Samarawickrama, D Y D

    2002-05-01

    The aims of the study were to test and compare the biaxial flexural strength and reliability of Empress 2 ceramics after heat treatment and the addition of the veneering material and to characterise their microstructures. Forty disc specimens (2 x 14 mm) and forty disc specimens (1 x 14 mm) were produced by heat pressing in the EP 500 press furnace. Group 1 (2 x 14 mm Empress 2 core) was as heat pressed and group 2 (2 x 14 mm Empress 2 core) was subjected to the recommended firing cycles. Groups 3 and 4 (1 x 14 mm Empress 2 core) were veneered with the dentine material and heat-treated as per group 2. Groups 1, 2 and 3 were lapped to 800 grit silicon carbide paper on the compressive surface only and group 4 on both the compressive and tensile test surfaces. Twenty disc specimens per group were tested using the biaxial flexure test at a crosshead speed of 0.15 mm/min. Specimens were characterised using X-ray diffraction (XRD) and secondary electron imaging (SEM). Mean biaxial flexural strengths (MPa+/-SD) were group 1: 265.5+/-25.7; group 2: 251.3+/-30.2; group 3: 258.6+/-21.4 and group 4: 308.6+/-37.7. There was no statistical difference between groups 1, 2 and 3 (p>0.05), but differences for group 4 (pEmpress 2 core material and an amorphous glass and some evidence of a crystalline phase in the dentine material. CONCLUSIONS; Veneering or heat treatment of Empress 2 ceramics did not significantly affect the mean biaxial flexural strength (p>0.05) or reliability. Surface modification of the Empress 2 core material increased the mean biaxial flexural strength (p<0.05).

  18. Birch veneer and plywood demand: projected needs of the industry

    Science.gov (United States)

    Clark E. McDonald

    1969-01-01

    Production of hardwood plywood in the United States has increased steadily from 1955 to 1967 - almost doubling during this period (table 1). The peak year for shipments of hardwood plywood was 1965, for all species (1,668,313,000 square feet surface measure) and also for birch ( 600,72 3,000 square feet surface measure). The U.S. Bureau of Census figures are not...

  19. Michigan timber industry: An assessment of timber product output and use, 1990. Forest Service resource bulletin

    International Nuclear Information System (INIS)

    Hackett, R.L.; Pilon, J.

    1993-01-01

    The bulletin discusses recent Michigan forest industry trends and reports the results of a detailed study of forest industry, industrial roundwood production, and associated primary mill wood and bark residue in Michigan in 1990. Such detailed information is necessary for intelligent planning and decisionmaking in wood procurement, forest resource management, and forest industry development. Likewise, researchers need current forest industry and industrial roundwood information for planning projects. All board foot data in the report have been converted to International 1/4 inch scale by applying a multiplier of 1.08 to all saw-log volume reported in Scribner Decimal C scale by sawmills, a multiplier of 1.04 to all veneer log volume reported in Scribner Decimal C scale by veneer mills, a multiplier of 1.38 to all saw-log volume reported in Doyle scale by sawmills, and a multiplier of 1.14 to all veneer log volume reported in Doyle scale by veneer mills

  20. Bruxism in prospective studies of veneered zirconia restorations-a systematic review.

    Science.gov (United States)

    Schmitter, Marc; Boemicke, Wolfgang; Stober, Thomas

    2014-01-01

    The objectives of this work were to systematically review the effect of bruxism on the survival of zirconia restorations on teeth and to assess the prevalence of nocturnal masseter muscle activity in a clinical sample. A Medline search was performed independently and in triplicate using the term "zirconia" and activating the filter "clinical trial." Furthermore, three other electronic databases were searched using the same term. Only papers published in English on prospective studies of veneered zirconia frameworks on teeth were included. To estimate the prevalence of sleep bruxism in clinical settings, subjects with no clinical signs of bruxism and who did not report grinding and/or clenching were examined by use of a disposable electromyographic device. The initial search resulted in 107 papers, of which 22 were included in the analysis. Bruxers were excluded in 20 of these articles. In 1 study bruxers were not excluded, and 1 study did not provide information regarding this issue. The methods used to identify bruxers were heterogeneous/not described, and no study used reliable, valid methods. Of 33 subjects without clinical signs of bruxism, nocturnal muscle activity exceeded predefined muscle activity for 63.8% of the subjects. There is a lack of information about the effect of bruxism on the incidence of technical failure of veneered zirconia restorations because all available studies failed to use suitable instruments for diagnosis of bruxism. Nocturnal muscle activity without clinical symptoms/report of bruxism was observed for a relevant number of patients.

  1. Visual versus Colorimetric Data Analysis for Color Determination in Resin Veneers

    Directory of Open Access Journals (Sweden)

    Raluca DIMA

    2012-03-01

    Full Text Available The color of natural teeth depends on their capacity to modify the incident light (to change the wave length of incident light. Mainly two types of observation modes are used: diffuse illumination 0% and 45%; the angles represent incidence of illumination and observation on the surface of the object whose color is determined. The patients have been properly selected to receive direct resin veneers on their frontal maxillary incisors. Visually we observed and determined color directly using natural incident light between 10 am and 16 pm, the observer was positioned away from patient so the tooth to examine was at the level of observer’s eye (incidence angles were mainly similar. Vita Easy Shade colorimeter was used to establish the color of the restoration before and after it was performed. The Expanded Visual Rating Scale for Appearance Match (EVRSAM supplied statistically comparable data as the literature; the comparison between visual and colorimetric data makes us suppose that visual color determination is a necessary but not sufficient tool for the esthetic success of any veneer restoration.

  2. Effect of luting agent on the load to failure and accelerated-fatigue resistance of lithium disilicate laminate veneers

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Ozcan, Mutlu; Carualho, Marco; Lazari, Priscilla; Cune, Marco S.; Razavi, Peywand; Magne, Pascal

    2017-01-01

    Objective. The aim of this study was to investigate the influence of the luting agent on the application of laminate veneers (LVs) in an accelerated fatigue and load-to-failure test after thermo-cyclic aging. Methods. Sound maxillary central incisors (N = 40) were randomly divided into four groups

  3. Effect of immediate and delayed dentin sealing on the fracture strength, failure type and Weilbull characteristics of lithiumdisilicate laminate veneers

    NARCIS (Netherlands)

    Gresnigt, Marco M.M.; Cune, Marco S.; de Roos, Joanne G.; Özcan, Mutlu

    OBJECTIVES: Adhesion on dentin is less reliable than on enamel, which could affect the durability of laminate veneers (LV). Immediate dentin sealing (IDS) is suggested instead of delayed dentin sealing (DDS) to overcome hypersensitivity and prevent debonding from dentin. This study evaluated the

  4. Foam Core Particleboards with Intumescent FRT Veneer: Cone Calorimeter Testing With Varying Adhesives, Surface Layer Thicknesses, and Processing Conditions

    Science.gov (United States)

    Mark A. Dietenberger; Johannes Welling; Ali Shalbafan

    2014-01-01

    Intumescent FRT Veneers adhered to the surface of foam core particleboard to provide adequate fire protection were evaluated by means of cone calorimeter tests (ASTM E1354). The foam core particleboards were prepared with variations in surface layer treatment, adhesives, surface layer thicknesses, and processing conditions. Ignitability, heat release rate profile, peak...

  5. The influence of log soaking temperature on surface quality and integrity performance of birch (Betula pendula Roth) veneer

    Science.gov (United States)

    Anti Rohumaa; Toni Antikainen; Christopher G. Hunt; Charles R. Frihart; Mark Hughes

    2016-01-01

    Wood material surface properties play an important role in adhesive bond formation and performance. In the present study, a test method was developed to evaluate the integrity of the wood surface, and the results were used to understand bond performance. Materials used were rotary cut birch (Betula pendula Roth) veneers, produced from logs soaked at 20 or 70 °C prior...

  6. Effect of Static and Cyclic Loading on Ceramic Laminate Veneers Adhered to Teeth with and Without Aged Composite Restorations

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Ozcan, Mutlu; Kalk, Warner; Galhano, Graziela

    2011-01-01

    Purpose: Existing composite restorations on teeth are often remade prior to the cementation of fixed dental prostheses. The aim of this study was to evaluate the effect of static and cyclic loading on ceramic laminate veneers adhered to aged resin composite restorations. Materials and Methods:

  7. Randomized Clinical Trial of Indirect Resin Composite and Ceramic Veneers : Up to 3-year Follow-up

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, Mutlu

    2013-01-01

    Purpose: This randomized controlled split-mouth clinical trial evaluated the short-term survival rate of indirect resin composite and ceramic laminate veneers. Materials and Methods: A total of 10 patients (mean age: 48.6 years) received 46 indirect resin composite (Estenia; n = 23) and ceramic

  8. Survival of ceramic veneers made of different materials after a minimum follow-up period of five years: a systematic review and meta-analysis.

    Science.gov (United States)

    Petridis, Haralampos P; Zekeridou, Alkisti; Malliari, Maria; Tortopidis, Dimitrios; Koidis, Petros

    2012-01-01

    The purpose of this systematic review was to compare the survival and complication rates of ceramic veneers produced with different techniques and materials after a minimum follow-up time of 5 years. A literature search was conducted, using electronic databases, relevant references, citations and journal researching, for clinical studies reporting on the survival of ceramic veneers fabricated with different techniques and materials with a mean followup time of at least 5 years. The search period spanned from January 1980 up to October 2010. Event rates were calculated for the following complications associated with ceramic veneers: fracture, debonding, marginal discoloration, marginal integrity, and caries. Summary estimates, and 5-year event rates were reported. Comparison between subgroups of different materials, as well as statistical significance, was calculated using a mixed effects model. Nine studies were selected for final analysis over an initial yield of 409 titles. No study directly compared the incidence of complications between ceramic veneers fabricated from different materials. Four of the included studies reported on the survival of ceramic veneers made out of feldspathic ceramics; four studies were on glass-ceramic veneers and one study included veneers fabricated from both materials. The mean observation time ranged between 5 and 10 years. Overall, the 5-year complication rates were low, with the exception of studies reporting on extended ceramic veneers. The most frequent complication reported was marginal discoloration (9% at 5 years), followed by marginal integrity (3.9-7.7% at 5 years). There was no statistically significant difference in the event rates between the subgroups of different materials (feldspathic vs. glass-ceramic). The results of this systematic review showed that ceramic veneers fabricated from feldspathic or glass-ceramics have an adequate clinical survival for at least 5 years of clinical service, with very low complication

  9. Residual stress profiles in veneering ceramic on Y-TZP, alumina and ZTA frameworks: measurement by hole-drilling.

    Science.gov (United States)

    Fukushima, K A; Sadoun, M J; Cesar, P F; Mainjot, A K

    2014-02-01

    The residual stress profile developed within the veneering ceramic during the manufacturing process is an important predicting factor in chipping failures, which constitute a well-known problem with yttria-tetragonal-zirconia polycrystal (Y-TZP) based restorations. The objectives of this study are to measure and to compare the residual stress profile in the veneering ceramic layered on three different polycrystalline ceramic framework materials: Y-TZP, alumina polycrystal (AL) and zirconia toughened alumina (ZTA). The stress profile was measured with the hole-drilling method in bilayered disk samples of 19 mm diameter with a 0.7 mm thick Y-TZP, AL or ZTA framework and a 1.5mm thick layer of the corresponding veneering ceramic. The AL samples exhibited increasing compressive stresses with depth, while compressive stresses switching into interior tensile stresses were measured in Y-TZP samples. ZTA samples exhibited compressive stress at the ceramic surface, decreasing with depth up to 0.6mm from the surface, and then becoming compressive again near the framework. Y-TZP samples exhibited a less favorable stress profile than those of AL and ZTA samples. Results support the hypothesis of the occurrence of structural changes within the Y-TZP surface in contact with the veneering ceramic to explain the presence of tensile stresses. Even if the presence of Y-TZP in the alumina matrix seems to negatively affect the residual stress profiles in ZTA samples in comparison with AL samples, the registered profiles remain positive in terms of veneer fracture resistance. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Short-Term Prospective Clinical Evaluation of Monolithic and Partially Veneered Zirconia Single Crowns.

    Science.gov (United States)

    Bömicke, Wolfgang; Rammelsberg, Peter; Stober, Thomas; Schmitter, Marc

    2017-02-01

    The purpose of this study was to prospectively evaluate the short-term clinical performance and esthetics of monolithic and partially (i.e., facially) veneered zirconia single crowns (MZC and PZC, respectively). Between September 2011 and June 2013, 68 participants received 90 MZCs and 72 PZCs. Clinical study documentation was performed at crown cementation (baseline), at the 6-month follow-up, and then yearly thereafter using standardized report forms. Eight participants with 14 single crowns (eight MZCs and six PZCs) dropped out during clinical follow-up. Thus, 60 participants (28 male, mean age 62.5 ± 13.1 years) fitted with 82 MZCs and 66 PZCs were analyzed in February 2016 (Kaplan-Meier survival; mean observation time for the restorations 35.1 ± 6.3 months). Descriptive statistics were calculated for participants' and dentists' esthetic ratings on a numerical rating scale from 0 to 10 (0 = unacceptable color and shape; 10 = excellent color and shape). Complications were predominantly biological in nature. One PZC was affected by minor chipping. Cumulative 3-year failure-free survival was 98.5% (standard error (SE), 1.5%) for both MZCs and PZCs. Three-year cumulative complication-free survival (success) was 93.6% (SE 2.8%) for MZCs and 95.5% (SE 2.6%) for PZCs. Three-year cumulative fracture-free survival was 100% for MZCs and 98.5% (SE 1.5%) for PZCs. Crowns of both types were awarded high esthetic scores by participants and dentists. Monolithic and partially veneered zirconia crowns can be used clinically with excellent short-term survival and success and without compromising esthetic appearance. Longer-term follow-up is, however, desirable. During the observation time, both monolithic and partially veneered zirconia crowns showed an outstanding low technical complication rate: only one minor chipping and three losses of retention were observed. Additionally, esthetics was excellent. Based on these results the clinical use of this kind of

  11. Occupational health and safety issues in Ontario sawmills and veneer/plywood plants: a pilot study.

    Science.gov (United States)

    Verma, Dave K; Demers, Cecil; Shaw, Don; Verma, Paul; Kurtz, Lawrence; Finkelstein, Murray; des Tombe, Karen; Welton, Tom

    2010-01-01

    A pilot study was conducted within the Ontario sawmill and veneer/plywood manufacturing industry. Information was collected by postal questionnaire and observational walk-through surveys. Industrial hygiene walk-through surveys were conducted at 22 work sites, and measurements for wood dust, noise, and bioaerosol were taken. The aim of the study was to obtain data on the current status regarding health and safety characteristics and an estimate of wood dust, noise, and bioaerosol exposures. The occupational exposure to wood dust and noise are similar to what has been reported in this industry in Canada and elsewhere. Airborne wood dust concentration ranged between 0.001 mg/m³ and 4.87 mg/m³ as total dust and noise exposure ranged between 55 and 117 dB(A). The study indicates the need for a more comprehensive industry-wide study of wood dust, noise, and bioaersols.

  12. Design of pedestrian truss bridge with Sengon-Rubber laminated veneer lumber

    Science.gov (United States)

    Herbudiman, B.; Pranata, Y. A.; Pangestu, L.

    2017-12-01

    Timber bridges are one of the bridge that has long been used, but nowadays, large dimension of sawn timber has limited supply and also it is not environmental-friendly. Laminated veneer lumber (LVL) is a engineered wood that becomes one of the promising alternative, because it is made from lower quality wood that processed to be used as a more quality one. The bridge planned to be a pedestrian truss bridge with length of 9 m, width of 3 m, height of 2.5 m, and using bolt and steel plate as its connection system. Mechanical properties of LVL obtained directly from laboratory test result. Bridge modeling and planning for wood construction refers to SNI 7973:2013, while the loading refers to SNI 1725:2016. Based on the modelling and calculation, the dimension of truss frame and girder beam which are 9 cm x 9 cm and 9 cm x 18 cm have adequate strengths and satisfy deflection requirement.

  13. Effects of multiple firings on the microstructure of zirconia and veneering ceramics.

    Science.gov (United States)

    Alkurt, Murat; Yeşil Duymus, Zeynep; Gundogdu, Mustafa

    2016-01-01

    The aim of study was to evaluate the effects of multiple firings on the microstructures of zirconia and two ceramics. Vita VM9 (VMZ) and Cerabien ZR (C-Z) ceramics on a zirconia framework and zirconia without veneering ceramic (WO-Z) were evaluated. Firing methods included firing two, five, and ten times (n=10). The effects of multiple firings on the surface hardness of the materials were evaluated using a Vickers hardness (HV) tester. Data were analyzed by two-way ANOVA and Tukey's test (α=0.05). After firing five and ten times, the hardness of VM-Z and C-Z increased significantly (p0.05). In the XRD analysis, zirconia had similar tetragonal (t)-monoclinic (m) phase transformations of Y-TZP after the different firing times. Clinically, multiple firings did not affect the microstructure of zirconia, but the structures of the two ceramics were affected.

  14. Occupational Health and Safety Issues in Ontario Sawmills and Veneer/Plywood Plants: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Dave K. Verma

    2010-01-01

    Full Text Available A pilot study was conducted within the Ontario sawmill and veneer/plywood manufacturing industry. Information was collected by postal questionnaire and observational walk-through surveys. Industrial hygiene walk-through surveys were conducted at 22 work sites, and measurements for wood dust, noise, and bioaerosol were taken. The aim of the study was to obtain data on the current status regarding health and safety characteristics and an estimate of wood dust, noise, and bioaerosol exposures. The occupational exposure to wood dust and noise are similar to what has been reported in this industry in Canada and elsewhere. Airborne wood dust concentration ranged between 0.001 mg/m3 and 4.87 mg/m3 as total dust and noise exposure ranged between 55 and 117 dB(A. The study indicates the need for a more comprehensive industry-wide study of wood dust, noise, and bioaersols.

  15. Minimally invasive restoration of a maxillary central incisor with a partial veneer.

    Science.gov (United States)

    Horvath, Sebastian; Schulz, Claus-Peter

    2012-01-01

    Minimally invasive treatment modalities allow for the preservation of sound tooth substance. However, by limiting the preparation to the extent of a defect, the transition between restoration and natural tooth may be moved to more visible areas. The materials available for the restoration of a limited defect in the anterior area are either resin composite materials or porcelain. A patient was presented who asked for the replacement of a discolored filling on the maxillary right central incisor. Tooth preparation was limited to the extent of the old filling, and a porcelain partial veneer restoration was fabricated. Despite the horizontal finish line in the middle of the clinical crown, a result could be achieved that was regarded as a success by the patient. This type of restoration proves to be a suitable alternative to direct composite restorations in the anterior area for the reconstruction of a limited defect, eg, due to a dental trauma.

  16. Ceramic materials for porcelain veneers: part II. Effect of material, shade, and thickness on translucency.

    Science.gov (United States)

    Barizon, Karine T L; Bergeron, Cathia; Vargas, Marcos A; Qian, Fang; Cobb, Deborah S; Gratton, David G; Geraldeli, Saulo

    2014-10-01

    Information regarding the differences in translucency among new ceramic systems is lacking. The purpose of this study was to compare the relative translucency of the different types of ceramic systems indicated for porcelain veneers and to evaluate the effect of shade and thickness on translucency. Disk specimens 13 mm in diameter and 0.7-mm thick were fabricated for the following 9 materials (n=5): VITA VM9, IPS Empress Esthetic, VITA PM9, Vitablocks Mark II, Kavo Everest G-Blank, IPS Empress CAD, IPS e.max CAD, IPS e.maxPress, and Lava Zirconia. VITA VM9 served as the positive control and Lava as the negative control. The disks were fabricated with the shade that corresponds to A1. For IPS e.maxPress, additional disks were made with different shades (BL2, BL4, A1, B1, O1, O2, V1, V2, V3), thickness (0.3 mm), and translucencies (high translucency, low translucency). Color coordinates (CIE L∗ a∗ b∗) were measured with a tristimulus colorimeter. The translucency parameter was calculated from the color difference of the material on a black versus a white background. One-way ANOVA, the post hoc Tukey honestly significant difference, and the Ryan-Einot-Gabriel-Welsch multiple range tests were used to analyze the data (α=.05). Statistically significant differences in the translucency parameter were found among porcelains (PPM9, Empress Esthetic>Empress CAD>Mark II, Everest, e.max CAD>e.max Press>Lava. Significant differences also were noted when different shades and thickness were compared (Pceramic systems designed for porcelain veneers present varying degrees of translucency. The thickness and shade of lithium disilicate ceramic affect its translucency. Shade affects translucency parameter less than thickness. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  17. Effect of resin shades on opacity of ceramic veneers and polymerization efficiency through ceramics.

    Science.gov (United States)

    Öztürk, Elif; Chiang, Yu-Chih; Coşgun, Erdal; Bolay, Şükran; Hickel, Reinhard; Ilie, Nicoleta

    2013-11-01

    The aim of this study was to assess the effect of different resin cement shades on the opacity and color difference of ceramics and to determine the polymerization efficiency of the resin cement at different shades after curing through ceramics. Two different ceramics (IPS e.max Press and IPS Empress(®)CAD, Ivoclar Vivadent) were used for this study. A light-cured veneer luting resin (Variolink Veneer, Ivoclar Vivadent) in four different shades of HV+1, HV+3, LV-1, and LV-3 was used for the colorimetric measurements. The color and spectral reflectance of the ceramics were measured according to the CIELab color scale relative to the standard illuminant D65 on a reflection spectrophotometer (ColorEye7000A, USA). Color differences (ΔE values) and the contrast ratios (CR) of the different groups of samples were calculated. In order to analyse the polymerization efficiency of the resin cements, the micromechanical properties of the resins were measured with an automatic microhardness indenter (Fisherscope H100C, Germany). The results were analysed using one-way ANOVA and Tukey's HSD post hoc tests (SPSS 18.0). The one-way ANOVA test showed that the values of ΔE and CR of the different specimen groups were significantly different (p<0.05). Group 1 (20.7 ± 0.5) (IPS-CAD without resin cement) exhibited the highest and group 10 (14.8 ± 0.5) (e.max:HV+3) exhibited the lowest ΔE value. Significant differences in the micromechanical properties were identified among the tested resin cements in different shades (p<0.05). Resin cement shade is an important factor for the opacity of a restoration. Furthermore, the resin shade affects the micromechanical properties of the underlying resin cement. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. The effect of veneering on the marginal fit of CAD/CAM-generated, copy-milled, and cast metal copings.

    Science.gov (United States)

    Ates, Sabit Melih; Yesil Duymus, Zeynep; Caglar, Ipek; Hologlu, Bilal

    2017-11-01

    This in vitro study investigated the marginal fit of metal and zirconia copings before and after veneering on dies with shoulder/chamfer (s/c) finish lines. Using CAD/CAM, ten (n = 10) each s/c zirconia (NZ) copings and ten (n = 10) each s/c metal (MM) copings were generated. As controls, ten (n = 10) each s/c zirconia copings were copy-milled (ZZ) and ten (n = 10) each s/c metal copings were cast (CC). The vertical marginal discrepancy of the copings was measured at 20 predefined spots of the circular shoulder and chamfer finish lines in microns (μm) before and after a first and a second veneering firing using a stereomicroscope at ×40 magnification. Data were statistically analyzed, and the comparisons of CAD/CAM-milled (NZ, MM), copy-milled (ZZ), and cast (CC) copings before and after veneering were made at a significance level of p < 0.05. Gap width at s/c finish lines of ZZ was (91 ± 11/100 ± 28) and increased significantly (109 ± 21/141 ± 18) after the first firing (ZZ1). NZ showed significantly smaller gaps than ZZ (36 ± 6/46 ± 12) and (NZ1) after the first firing (61 ± 16/71 ± 29). Gap widths of CC groups (36 ± 8/25 ± 4) were not significantly different from NZ but were significantly lower after the (CC1) first veneering firing (40 ± 8/42 ± 7). MM copings showed gap values similar to NZ. Second firings did not significantly increase gaps in all groups except ZZ2 of chamfer finish line. Veneering increased the marginal gap width of copings. Within the limits of this in vitro study, aesthetic ceramic veneering of CAD/CAM-generated copings caused a statistically significant but tolerable loss of marginal fit precision.

  19. The effect of core material, veneering porcelain, and fabrication technique on the biaxial flexural strength and weibull analysis of selected dental ceramics.

    Science.gov (United States)

    Lin, Wei-Shao; Ercoli, Carlo; Feng, Changyong; Morton, Dean

    2012-07-01

    The objective of this study was to compare the effect of veneering porcelain (monolithic or bilayer specimens) and core fabrication technique (heat-pressed or CAD/CAM) on the biaxial flexural strength and Weibull modulus of leucite-reinforced and lithium-disilicate glass ceramics. In addition, the effect of veneering technique (heat-pressed or powder/liquid layering) for zirconia ceramics on the biaxial flexural strength and Weibull modulus was studied. Five ceramic core materials (IPS Empress Esthetic, IPS Empress CAD, IPS e.max Press, IPS e.max CAD, IPS e.max ZirCAD) and three corresponding veneering porcelains (IPS Empress Esthetic Veneer, IPS e.max Ceram, IPS e.max ZirPress) were selected for this study. Each core material group contained three subgroups based on the core material thickness and the presence of corresponding veneering porcelain as follows: 1.5 mm core material only (subgroup 1.5C), 0.8 mm core material only (subgroup 0.8C), and 1.5 mm core/veneer group: 0.8 mm core with 0.7 mm corresponding veneering porcelain with a powder/liquid layering technique (subgroup 0.8C-0.7VL). The ZirCAD group had one additional 1.5 mm core/veneer subgroup with 0.7 mm heat-pressed veneering porcelain (subgroup 0.8C-0.7VP). The biaxial flexural strengths were compared for each subgroup (n = 10) according to ISO standard 6872:2008 with ANOVA and Tukey's post hoc multiple comparison test (p≤ 0.05). The reliability of strength was analyzed with the Weibull distribution. For all core materials, the 1.5 mm core/veneer subgroups (0.8C-0.7VL, 0.8C-0.7VP) had significantly lower mean biaxial flexural strengths (p Empress and e.max groups, regardless of core thickness and fabrication techniques. Comparing fabrication techniques, Empress Esthetic/CAD, e.max Press/CAD had similar biaxial flexural strength (p= 0.28 for Empress pair; p= 0.87 for e.max pair); however, e.max CAD/Press groups had significantly higher flexural strength (p Empress Esthetic/CAD groups. Monolithic core

  20. 76 FR 35474 - Colville Indian Plywood and Veneer, Colville Tribal Enterprise Corporation Wood Products Division...

    Science.gov (United States)

    2011-06-17

    ... Logging, Mccuen Jones, San Poil Logging, Scott Thorndike, Silver Nichol Trucking and Stensgar Logging..., Mawdsley Logging, McCuen Jones, San Poil Logging, Scott Thorndike, Silver Nichol Trucking and Stensgar...

  1. 75 FR 41896 - Colville Indian Plywood and Veneer Colville Tribal Enterprise Corporation Wood Products Division...

    Science.gov (United States)

    2010-07-19

    ... Logging, Lone Rock Contracting, Mawdsley Logging, Mccuen Jones, San Poil Logging, Scott Thorndike, Silver... McCuen Jones, San Poil Logging, Scott Thorndike, Silver Nichol Trucking and Stensgar Logging were... Logging, Scott Thorndike, Silver Nichol Trucking and Stensgar Logging, Omak, Washington, who became...

  2. PRELIMINARY STUDY OF PLYWOOD PRODUCED WITH PARICÁ (Schizolobium amazonicum Huber ex Ducke VENEERS MODIFIED BY THERMO-MECHANICAL TREATMENT

    Directory of Open Access Journals (Sweden)

    Larissa Medeiros Arruda

    2011-05-01

    Full Text Available The objective of this preliminary research was to study the effects of thermo-mechanical modification in veneers of Paricá (Schizolobium amazonicum Huber ex Ducke to improve plywood hygroscopicity and mechanical properties. The amount of 24 veneers was used with the dimensions 25 x 25 cm, that were compressed under different times (5, 10 and 15 minutes at 150°C and pressure at 1 N.mm-2, constituting three treatments and one untreated. Plywood were bonded with resorcinol-formaldehyde, glue consumption of 360 g.m-2 at ambient temperature and pressure of 1 N.mm-2 for 10 hours. The samples were evaluated by colorimetric analysis and physical and mechanical properties. Colorimetric analysis showed that there was a darkening of the wood toward the increase of treatment time. The treatment was not efficient in reducing swelling, only reducing absorption of water. The mechanical properties were not significantly affected by the treatment.

  3. Rehabilitation of a patient with amelogenesis imperfecta using porcelain veneers and CAD/CAM polymer restorations: A clinical report.

    Science.gov (United States)

    Saeidi Pour, Reza; Edelhoff, Daniel; Prandtner, Otto; Liebermann, Anja

    2015-01-01

    The complete dental rehabilitation of patients with a vertical dimension loss (VDL) caused by structural enamel deficits associated with amelogenesis imperfecta (AI) represents a difficult challenge for restorative teams. Accurate analysis and treatment planning that includes esthetic and functional evaluations and adequate material selection are important prerequisites for successful results. Long-term provisional restorations play an important role in exploring and elucidating the patients' esthetic demands and functional needs. Restorative treatment options can vary from requiring only oral hygiene instructions to extensive dental restorations that include composite fillings, ceramic veneers, metal-ceramic, or all-ceramic crowns. This case report describes a full-mouth rehabilitation of a patient with amelogenesis imperfecta including the case planning, bite replacement, preparation, and restoration setting steps with an experimental CAD/CAM polymer and porcelain veneers.

  4. Influence of zirconia framework thickness on residual stress profile in veneering ceramic: measurement by hole-drilling.

    Science.gov (United States)

    Mainjot, Amélie K; Schajer, Gary S; Vanheusden, Alain J; Sadoun, Michaël J

    2012-04-01

    Framework design is reported to influence chipping in zirconia-based restorations, which is an important cause of failure of such restorations. Residual stress profile in the veneering ceramic after the manufacturing process is an important predictive factor of the mechanical behavior of the material. The objective of this study is to investigate the influence of framework thickness on the stress profile measured in zirconia-based structures. The stress profile was measured with the hole-drilling method in bilayered disc samples of 20mm diameter with a 1.5 mm thick veneering ceramic layer. Six different framework thicknesses from 0.5 mm to 3 mm were studied. Two different cooling procedures were also investigated. Compressive stresses were observed in the surface, and tensile stresses in the depth of most of the samples. The slow cooling procedure was found to promote the development of interior tensile stresses, except for the sample with a 3mm thick framework. With the tempering procedure, samples with a 1.5 mm thick framework exhibited the most favorable stress profile, while thicker and thinner frameworks exhibited respectively in surface or interior tensile stresses. The measurements performed highlight the importance of framework thickness, which determine the nature of stresses and can explain clinical failures encountered, especially with thin frameworks. The adequate ratio between veneering ceramic and zirconia is hard to define, restricting the range of indications of zirconia-based restorations until a better understanding of such a delicate veneering process is achieved. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Marginal Vertical Discrepancies of Monolithic and Veneered Zirconia and Metal-Ceramic Three-Unit Posterior Fixed Dental Prostheses.

    Science.gov (United States)

    Lopez-Suarez, Carlos; Gonzalo, Esther; Pelaez, Jesus; Serrano, Benjamin; Suarez, Maria J

    2016-01-01

    The aim of this study was to investigate and compare the marginal fit of posterior fixed dental prostheses (FDPs) made of monolithic and veneered computer-aided design/computer-assisted manufacture (CAD/CAM) zirconia ceramic with metal-ceramic posterior FDPs. Thirty standardized steel dies were prepared to receive posterior three-unit FDPs. Specimens were randomly divided into three groups (n = 10): (1) metal-ceramic (control group), (2) veneered zirconia, and (3) monolithic zirconia. All FDPs were cemented using a glass-ionomer cement. The specimens were subjected to thermal cycling (5°C to 55°C). A scanning electron microscope (SEM) with a magnification of ×500 was used for measurements. The data were statistically analyzed using one-way analysis of variance and paired t test. Both zirconia groups showed similar vertical marginal discrepancies, and no significant differences (P = .661) in marginal adaptation were observed among the groups. No differences were observed in either group in marginal discrepancies between surfaces or abutments. Monolithic zirconia posterior FDPs exhibit similar vertical marginal discrepancies to veneered zirconia posterior FDPs. No influence of localization measurements was observed.

  6. Effect of autoclave induced low-temperature degradation on the adhesion energy between yttria-stabilized zirconia veneered with porcelain.

    Science.gov (United States)

    Li, Kai Chun; Waddell, J Neil; Prior, David J; Ting, Stephanie; Girvan, Liz; van Vuuren, Ludwig Jansen; Swain, Michael V

    2013-11-01

    To investigate the effect of autoclave induced low-temperature degradation on the adhesion energy between yttria-stabilized zirconia veneered with porcelain. The strain energy release rate using a four-point bending stable fracture test was evaluated for two different porcelains [leucite containing (VM9) and glass (Zirox) porcelain] veneered to zirconia. Prior to veneering the zirconia had been subjected to 0 (control), 1, 5, 10 and 20 autoclave cycles. The specimens were manufactured to a total bi-layer dimension of 30 mm × 8 mm × 3 mm. Subsequent scanning electron microscopy/energy dispersive spectrometry, electron backscatter diffraction and X-ray diffraction analysis were performed to identify the phase transformation and fracture behavior. The strain energy release rate for debonding of the VM9 specimens were significantly higher (pautoclave cycles lowered the strain energy release rate significantly (pautoclave cycles between 5 and 20. The monoclinic phase reverted back to tetragonal phase after undergoing conventional porcelain firing cycles. EBSD data showed significant changes of the grain size distribution between the control and autoclaved specimen (cycle 20). Increasing autoclave cycles only significantly decreased the adhesion of the VM9 layered specimens. In addition, a conventional porcelain firing schedule completely reverted the monoclinic phase back to tetragonal. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Comparison of Marginal and Internal Adaptation of Heat-Pressed and CAD/CAM Porcelain Laminate Veneers and a 2-Year Follow-Up.

    Science.gov (United States)

    Yuce, Mert; Ulusoy, Mubin; Turk, Ayse Gozde

    2017-12-22

    To compare marginal and internal adaptations of porcelain laminate veneers fabricated with heat-pressed and CAD/CAM techniques, and to evaluate the clinical performances 2 years after cementation. Thirty heat-pressed and 31 CAD/CAM porcelain laminate veneers were fabricated for 12 patients. Silicone replicas of each veneer were obtained. Replicas were sectioned into 4 parts to measure adaptations of the veneers. A stereomicroscope was used to measure from 3 locations of replicas for marginal, and 9 locations for internal adaptations at 40x magnification. Clinical evaluations were done at baseline and 6, 12, 18, and 24 months after cementation according to the modified United States Public Health Service (USPHS) criteria. Independent samples t-test compared the adaptation values between heat-pressed and CAD/CAM groups. Paired t-test was used to evaluate marginal and internal adaptations of each group. Differences between the modified USPHS criteria ratings of heat-pressed and CAD/CAM groups were determined by the Mann-Whitney U test. Kaplan-Meier analysis was used to analyze the survival ratings of the veneers (p CAD/CAM veneers were 295 and 314.98 μm, respectively, and there was no statistically significant difference (p = 0.541). Internal adaptation values of groups were not statistically different either (201.82 μm for heat pressed; 195.47 μm for CAD/CAM p = 0.734). When marginal and internal adaptation values were compared within groups, there were significant differences both for heat-pressed (p CAD/CAM (p CAD/CAM or heat-pressed, had no effect on the marginal and internal adaptation of porcelain laminate veneers. The results showed that both fabrication techniques performed well after 2 years of clinical performance. © 2017 by the American College of Prosthodontists.

  8. Fracture and shear bond strength analyses of different dental veneering ceramics to zirconia

    International Nuclear Information System (INIS)

    Diniz, Alexandre C.; Nascimento, Rubens M.; Souza, Julio C.M.; Henriques, Bruno B.; Carreiro, Adriana F.P.

    2014-01-01

    The purpose of this work was to evaluate the interaction of different layering porcelains with zirconia via shear bond strength test and microscopy. Four different groups of dental veneering porcelains (VM9, Zirkonzanh, Ceramco, IPS) were fused onto forty zirconia-based cylindrical substrates (8 mm in diameter and 12 mm in height) (n = 10), according to the manufacturer's recommendations. Additionally, layered dental porcelain (D-sign, Ivoclar) was fired on ten Ni–Cr cylindrical substrates Shear bond strength tests of the veneering porcelain to zirconia or Ni–Cr were carried out at a crosshead speed of 0.5 mm/min. After the shear bond tests, the interfaces were analyzed by scanning electron microscopy (SEM). The fracture type exhibited by the different systems was also assessed. The results were statistically analyzed by ANOVA at a significant level of p < .05. The shear bond strength values of the porcelain-to-NiCr interfaces (25.3 ± 7.1 MPa) were significantly higher than those recorded for the following porcelain-to-zirconia systems: Zirkonzanh (18.8 ± 1 MPa), Ceramco (18.2 ± 4.7 MPa), and IPS (16 ± 4.5 MPa). However, no significant differences were found in the shear bond strength values between the porcelain-to-NiCr and porcelain (VM9)-to-zirconia (23.2 ± 5.1 MPa) groups (p > .05). All-ceramic interfaces revealed mixed failure type, cohesive in the porcelain and adhesive at the interface. This study demonstrated that all-ceramic systems do not attain yet the same bond strength standards equivalent to metal–ceramic systems. Therefore, despite the esthetic appeal of all-ceramic restorations, the adhesion between the porcelain and zirconia framework is still an issue considering the long term success of the restoration. - Highlights: • This study assessed the shear bond strength of different porcelains to zirconia. • The porcelain Vita VM9 showed a high shear bond strength to zirconia. • The fracture surface of all-ceramic systems revealed

  9. Fracture and shear bond strength analyses of different dental veneering ceramics to zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Diniz, Alexandre C. [School of Dentistry (DOD), Division of Prosthodontics, Universidade Federal do Rio Grande do Norte -UFRN, 59056-000, Natal (Brazil); Nascimento, Rubens M. [Materials Engineering Department, Universidade Federal do Rio Grande do Norte - UFRN, Natal (Brazil); Souza, Julio C.M. [Centre for Mechanics and Materials Technologies - CT2M, Department of Mechanical Engineering (DEM), Universidade do Minho, Campus Azurém, 4800-058, Guimarães (Portugal); Henriques, Bruno B. [Materials Engineering Department, Universidade Federal do Rio Grande do Norte - UFRN, Natal (Brazil); Centre for Mechanics and Materials Technologies - CT2M, Department of Mechanical Engineering (DEM), Universidade do Minho, Campus Azurém, 4800-058, Guimarães (Portugal); Carreiro, Adriana F.P., E-mail: adrianadafonte@hotmail.com [School of Dentistry (DOD), Division of Prosthodontics, Universidade Federal do Rio Grande do Norte -UFRN, 59056-000, Natal (Brazil)

    2014-05-01

    The purpose of this work was to evaluate the interaction of different layering porcelains with zirconia via shear bond strength test and microscopy. Four different groups of dental veneering porcelains (VM9, Zirkonzanh, Ceramco, IPS) were fused onto forty zirconia-based cylindrical substrates (8 mm in diameter and 12 mm in height) (n = 10), according to the manufacturer's recommendations. Additionally, layered dental porcelain (D-sign, Ivoclar) was fired on ten Ni–Cr cylindrical substrates Shear bond strength tests of the veneering porcelain to zirconia or Ni–Cr were carried out at a crosshead speed of 0.5 mm/min. After the shear bond tests, the interfaces were analyzed by scanning electron microscopy (SEM). The fracture type exhibited by the different systems was also assessed. The results were statistically analyzed by ANOVA at a significant level of p < .05. The shear bond strength values of the porcelain-to-NiCr interfaces (25.3 ± 7.1 MPa) were significantly higher than those recorded for the following porcelain-to-zirconia systems: Zirkonzanh (18.8 ± 1 MPa), Ceramco (18.2 ± 4.7 MPa), and IPS (16 ± 4.5 MPa). However, no significant differences were found in the shear bond strength values between the porcelain-to-NiCr and porcelain (VM9)-to-zirconia (23.2 ± 5.1 MPa) groups (p > .05). All-ceramic interfaces revealed mixed failure type, cohesive in the porcelain and adhesive at the interface. This study demonstrated that all-ceramic systems do not attain yet the same bond strength standards equivalent to metal–ceramic systems. Therefore, despite the esthetic appeal of all-ceramic restorations, the adhesion between the porcelain and zirconia framework is still an issue considering the long term success of the restoration. - Highlights: • This study assessed the shear bond strength of different porcelains to zirconia. • The porcelain Vita VM9 showed a high shear bond strength to zirconia. • The fracture surface of all-ceramic systems revealed

  10. A comparative study of progressive wear of four dental monolithic, veneered glass-ceramics.

    Science.gov (United States)

    Zhang, Zhenzhen; Yi, Yuanping; Wang, Xuesong; Guo, Jiawen; Li, Ding; He, Lin; Zhang, Shaofeng

    2017-10-01

    This study evaluated the wear performance and wear mechanisms of four dental glass-ceramics, based on the microstructure and mechanical properties in the progressive wear process. Bar (N = 40, n = 10) and disk (N = 32, n = 8) specimens were prepared from (A) lithium disilicate glass-ceramic (LD), (B) leucite reinforced glass-ceramic (LEU), (C) feldspathic glass-ceramic (FEL), and (D) fluorapatite glass-ceramic (FLU). The bar specimens were tested for three-point flexural strength, hardness, fracture toughness and elastic modulus. The disk specimens paired with steatite antagonists were tested in a pin-on-disk tribometer with 10N up to 1000,000 wear cycles. The wear analysis of glass-ceramics was performed using a 3D profilometer after every 200,000 wear cycles. Wear loss of steatite antagonists was calculated by measuring the weight and density using sensitive balance and Archimedes' method. Wear morphologies and microstructures were analyzed by scanning electron microscopy (SEM). The crystalline phase compositions were determined using X-ray diffraction (XRD). One-way analysis of variance (ANOVA) was used to analyze the data. Multiple pair-wise comparison of means was performed by Tukey's post-hoc test. LD showed the highest fracture toughness, flexural strength, elastic modulus and crystallinity, followed by LEU and FEL, and FLU showed the lowest. However, the hardness of LD was lower than all the other three types of ceramics. For steatite antagonists, LD produced the least wear loss of antagonist, followed by LEU and FEL, and FLU had the most wear loss. For glass-ceramic materials, LD exhibited similar wear loss as LEU, but more than FLU and FEL did. Moreover, fracture occurred on the wear surface of FLU. In the progressive wear process, veneering porcelains showed better wear resistance but fluorapatite veneering porcelains appeared fracture surface. Monolithic lithium disilicate glass-ceramics with higher mechanical properties showed more wear loss, however

  11. Pre-sintered Y-TZP sandblasting: effect on surface roughness, phase transformation, and Y-TZP/veneer bond strength

    Directory of Open Access Journals (Sweden)

    Carla Müller Ramos-Tonello

    Full Text Available Abstract Sandblasting is a common method to try to improve the Y-TZP/veneer bond strength of dental prostheses, however, it may put stress on zirconia surfaces and could accelerate the t→m phase transformation. Y-TZP sandblasting before sintering could be an alternative to improve surface roughness and bonding strength of veneering ceramic. Objectives. The aim of this study was to analyze the effect of Y-TZP pre-sintering sandblasting on surface roughness, phase transformation, and the Y-TZP/veneer shear bond strength. Material and Methods. The Y-TZP specimen surface underwent sandblasting with aluminum oxide (50 μm pre-sintering (Z-PRE and post-sintering (Z-POS. Z-CTR was not subjected to surface treatment. After ceramic veneer application, the specimens were subjected to shear bond testing. Surface roughness was analyzed by confocal microscopy. Y-TZP monoclinic and tetragonal phases were evaluated by micro-Raman spectroscopy. Shear bond strength and surface roughness data were analyzed by One-way ANOVA and Tukey tests (α=0.05. Differences in the wave numbers and the broadening bands of the Raman spectra were compared among groups. Results. Z-POS (9.73±5.36 MPa and Z-PRE (7.94±2.52 MPa showed the highest bond strength, significantly higher than that of Z-CTR (5.54±2.14 MPa. The Ra of Z-PRE (1.59±0.23 µm was much greater and significantly different from that of Z-CTR (0.29±0.05 µm and Z-POS (0.77±0.13 µm. All groups showed bands typical of the tetragonal (T and monoclinic (M phases. Y-TZP sandblasting before sintering resulted in rougher surfaces but did not increase the shear bond strength compared to post-sintering and increased surface defects. Conclusions. Surface treatment with Al3O2, regardless of the moment and application, improves the results of Y-TZP/veneer bonding and is not a specific cause of t→m transformation.

  12. Missouri timber industry--an assessment of timber product output and use.

    Science.gov (United States)

    W. Brad. Smith; Shelby Jones

    1990-01-01

    Discusses recent Missouri forest industry trends; production and receipts of saw logs; and production of charcoal, veneer logs, cooperage logs, and other products in 1987. Reports on logging residue, on wood and bark residue generated at primary wood-using mills, and on disposition of this residue.

  13. South Dakota timber industry: an assessment of timber product output and use, 2009

    Science.gov (United States)

    Ronald J. Piva; Gregory J. Josten

    2013-01-01

    Presents recent South Dakota forest industry trends; production and receipts of industrial roundwood; and production of saw logs, veneer logs, pulpwood, and other products in 2009. Logging residue generated from timber harvest operations is reported, as well as wood and bark residue generated at primary wood-using mills and disposition of mill residues.

  14. Wisconsin timber industry--an assessment of timber product output and use, 1988.

    Science.gov (United States)

    W. Brad Smith; James W. Whipple

    1990-01-01

    Discusses recent Wisconsin forest industry trends; production and receipts of pulpwood, saw logs, and veneer logs; and production of other timber products in 1988. Reports on logging residue, on wood and bark residue generated at primary wood-using mills, and on disposition of this mill residue.

  15. Effect of stacking sequence on mechanical properties neem wood veneer plastic composites

    Science.gov (United States)

    Nagamadhu, M.; Kumar, G. C. Mohan; Jeyaraj, P.

    2018-04-01

    This study investigates the effect of wood veneer stacking sequence on mechanical properties of neem wood polymer composite (WPC) experimentally. Wood laminated samples were fabricated by conventional hand layup technique in a mold and cured under pressure at room temperature and then post cured at elevated temperature. Initially, the tensile, flexural, and impact test were conducted to understand the effect of weight fraction of fiber on mechanical properties. The mechanical properties have increased with the weight fraction of fiber. Moreover the stacking sequence of neem wood plays an important role. As it has a significant impact on the mechanical properties. The results indicated that 0°/0° WPC shows highest mechanical properties as compared to other sequences (90°/90°, 0°/90°, 45°/90°, 45°/45°). The Fourier Transform Infrared Spectroscopy (FTIR) Analysis were carried out to identify chemical compounds both in raw neem wood and neem wood epoxy composite. The microstructure raw/neat neem wood and the interfacial bonding characteristics of neem wood composite investigated using Scanning electron microscopy images.

  16. Effect of provisional cements on shear bond strength of porcelain laminate veneers.

    Science.gov (United States)

    Altintas, Subutay Han; Tak, Onjen; Secilmis, Asli; Usumez, Aslihan

    2011-08-01

    The purpose of this study was to evaluate the effect of three provisional cements and two cleaning techniques on the final bond strength of porcelain laminate veneers. The occlusal third of the crowns of forty molar teeth were sectioned and embedded in autopolymerizing acrylic resin. Dentin surfaces were polished and specimens were randomly divided into four groups (n=10). Provisional restorations were fabricated and two provisional restorations were cemented onto each tooth. Restorations were fixed with one of three different provisional cements: eugenol-free provisional cement (Cavex), calcium hydroxide (Dycal), and light-cured provisional cement (Tempond Clear). Provisional restorations were removed with either a dental explorer and air-water spray, or a cleaning bur (Opticlean). In the control group, provisional restorations were not used on the surfaces of specimens. IPS Empress 2 ceramic discs were luted with a dual-cured resin cement (Panavia F). Shear bond strength was measured using a universal testing machine. Data were statistically analyzed by ANOVA, Tukey's HSD and Dunnett tests. Surfaces were examined by scanning electronic microscopy. Significant differences were found between the control group and both the light-cured provisional cement groups and the eugenol-free provisional cement-cleaning bur group (Pprovisional cement showed the lowest bond strength values. Selection of the provisional cement is an important factor in the ultimate bond strength of the final restoration. Calcium hydroxide provisional cement and cleaning with a dental explorer are advisable.

  17. Influence of various bonding techniques on the fracture strength of thin CAD/CAM-fabricated occlusal glass-ceramic veneers.

    Science.gov (United States)

    Yazigi, Christine; Kern, Matthias; Chaar, Mohamed Sad

    2017-11-01

    To evaluate the efficiency of immediate dentin sealing and the effects of different bonding protocols on the fracture strength of CAD/CAM occlusal veneers bonded to exposed dentin. Ninety-six extracted maxillary premolars were initially divided into three main groups with 32 specimens each: without immediate dentin sealing, immediate dentin sealing/total etching and immediate dentin sealing/selective etching. Teeth were identically prepared in the dentin to receive occlusal veneers of 0.8mm thickness, milled from lithium disilicate ceramic blocks (IPS e.max CAD). Each main group was later subdivided, according to the pre-cementation surface etching protocol (total/selective), into two subgroups with 16 specimens each. All restorations were adhesively bonded using a resin cement (Variolink Esthetic). Half of the specimens of each subgroup were subjected to thermo-dynamic loading in a chewing simulator with 1,200,000 cycles at 10kg load. The other half and the surviving specimens were subjected to quasi-static loading until failure. Statistical analysis was performed using three-way ANOVA and Tukey's post-hoc tests. All specimens except one survived the artificial aging. A significantly higher fracture strength of restorations (p ≤ 0.001) was obtained when immediate dentin sealing was followed regardless of the etching method with values ranging from a minimum of 1122 ± 336N to a maximum of 1853 ± 333N. Neither the pre-cementation treatment nor the artificial aging had a statistical significant effect on the fracture strength. Immediate dentin sealing protocol is recommended whenever dentin is exposed during the preparation for thin glass-ceramic occlusal veneers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. SEM evaluation of human gingival fibroblasts growth onto CAD/CAM zirconia and veneering ceramic for zirconia

    Science.gov (United States)

    Zizzari, Vincenzo; Borelli, Bruna; De Colli, Marianna; Tumedei, Margherita; Di Iorio, Donato; Zara, Susi; Sorrentino, Roberto; Cataldi, Amelia; Gherlone, Enrico Felice; Zarone, Fernando; Tetè, Stefano

    2013-01-01

    Summary Aim To evaluate the growth of Human Gingival Fibroblasts (HGFs) cultured onto sample discs of CAD/CAM zirconia and veneering ceramic for zirconia by means of Scanning Electron Microscope (SEM) analysis at different experimental times. Methods A total of 26 experimental discs, divided into 2 groups, were used: Group A) CAD/CAM zirconia (3Y-TZP) discs (n=13); Group B) veneering ceramic for zirconia discs (n=13). HGFs were obtained from human gingival biopsies, isolated and placed in culture plates. Subsequently, cells were seeded on experimental discs at 7,5×103/cm2 concentration and cultured for a total of 7 days. Discs were processed for SEM observation at 3h, 24h, 72h and 7 days. Results In Group A, after 3h, HGFs were adherent to the surface and showed a flattened profile. The disc surface covered by HGFs resulted to be wider in Group A than in Group B samples. At SEM observation, after 24h and 72h, differences in cell attachment were slightly noticeable between the groups, with an evident flattening of HGFs on both surfaces. All differences between Group A and group B became less significant after 7 days of culture in vitro. Conclusions SEM analysis of HGFs showed differences in terms of cell adhesion and proliferation, especially in the early hours of culture. Results showed a better adhesion and cell growth in Group A than in Group B, especially up to 72h in vitro. Differences decreased after 7 days, probably because of the rougher surface of CAD/CAM zirconia, promoting better cell adhesion, compared to the smoother surface of veneering ceramic. PMID:24611089

  19. Metal/silicate partitioning of Pt and the origin of the "late veneer"

    Science.gov (United States)

    Ertel, W.; Walter, M. J.; Drake, M. J.; Sylvester, P. J.

    2002-12-01

    Highly siderophile elements (HSEs) are perfect tools for investigating core forming processes in planetary bodies due to their Fe-loving (siderophile) geochemical behavior. Tremendous scientific effort was invested into this field during the past 10 years - mostly in 1 atm experiments. However, little is known about their high-pressure geochemistry and partitioning behavior between core and mantle forming phases. This knowledge is essential to distinguish between equilibrium (Magma Ocean) and non-equilibrium (heterogeneous accretion, late veneer) models for the accretion history for the early Earth. We therefore chose to investigate the partitioning behavior of Pt up to pressures of 140 kbar (14 GPa) and temperatures of 1950°C. The used melt composition - identical to melt systems used in 1 atm experiments - is the eutectic composition of Anorthite-Diopside (AnDi), a pseudo-basalt. A series of runs were performed which were internaly buffered by the piston cylinder apparatus, and were followed by duplicate experiments buffered in the AnDi-C-CO2 system. These experiments constitute reversals since they approach equilibrium from an initially higher and lower Pt solubility (8 ppm in the non-buffered runs, and essentially Pt free in the buffered runs). Experimental charges were encapsulated in Pt capsules which served as source for Pt. Experiments up to 20 kbar were performed in a Quickpress piston cylinder apparatus, while experiments at higher pressures were performed in a Walker-type (Tucson, AZ) and a Kawai-type (Misasa, Japan) multi anvil apparatus. Time series experiments were performed in piston-cylinder runs to determine minimum run durations for the achievement of equilibrium, and to guarantee high-quality partitioning data. 6 hours was found to be sufficient to obtain equilibrium. In practice, all experiments exceeded 12 hours to assure equilibrium. In a second set of runs the temperature dependence of the partitioning behavior of Pt was investigated between

  20. Influence of resin cement shade on the color and translucency of ceramic veneers

    Science.gov (United States)

    HERNANDES, Daiana Kelly Lopes; ARRAIS, Cesar Augusto Galvão; de LIMA, Erick; CESAR, Paulo Francisco; RODRIGUES, José Augusto

    2016-01-01

    ABSTRACT Objective This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3) layer on color change, translucency parameter (TP), and chroma of low (LT) and high (HT) translucent reinforced lithium disilicate ceramic laminates. Material and Methods One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent) was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick) under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE) of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B) and white (W) background readings was used for TP analysis, while chroma was calculated by the formula C* ab=(a*2+b*2)½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. Results HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Conclusions Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable. PMID:27556211

  1. Influence of polyurethane resin dies on the fit and adaptation of full veneer crowns.

    Science.gov (United States)

    Lillywhite, Graeme R R; Vohra, Fahim

    2015-01-01

    Polyurethane resin is a possible alternative to type IV dental stone for fabrication of indirect restorations however its dimensional accuracy is questionable. The aim was to investigate the dimensional accuracy of silica filled polyurethane resin die material by evaluating the marginal fit and adaptation of indirect gold castings. Experimental, in vitro study. Totally 40 copper plated replicas of a nickel chrome master die analogous to a veneer gold crown preparation were made and impressions recorded using polyvinylsiloxane material. Twenty impressions were poured in type IV dental stone (control group (Vel-mix, Kerr, UK) and the remaining (n = 20) in silica filled polyurethane die material (test group) (Alpha Die MF, CA, USA). Gold castings were fabricated for each die using standardized techniques. The castings were seated on their respective copper plated dies, embedded in resin and sectioned. The specimens were analyzed by measuring marginal opening and the area beneath the casting at a ×63 magnification and using image analysis software. Data were analyzed using a Student's t-test. No significant difference was observed between the experimental groups (P > 0.05). The mean marginal opening for type IV, dental stone and polyurethane resin, was 57 ± 22.6 μm and 63.47 ± 27.1 μm, respectively. Stone displayed a smaller area beneath the casting (31581 ± 16297 μm 2 ) as compared to polyurethane resin (35003 ± 23039 μm 2 ). The fit and adaptation of indirect gold castings made on polyurethane and type IV dental stone dies were comparable.

  2. Influence of resin cement shade on the color and translucency of ceramic veneers

    Directory of Open Access Journals (Sweden)

    Daiana Kelly Lopes HERNANDES

    Full Text Available ABSTRACT Objective This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3 layer on color change, translucency parameter (TP, and chroma of low (LT and high (HT translucent reinforced lithium disilicate ceramic laminates. Material and Methods One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B and white (W background readings was used for TP analysis, while chroma was calculated by the formula C*ab=(a*2+b*2½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. Results HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Conclusions Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable.

  3. Influence of resin cement shade on the color and translucency of ceramic veneers.

    Science.gov (United States)

    Hernandes, Daiana Kelly Lopes; Arrais, Cesar Augusto Galvão; Lima, Erick de; Cesar, Paulo Francisco; Rodrigues, José Augusto

    2016-01-01

    This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3) layer on color change, translucency parameter (TP), and chroma of low (LT) and high (HT) translucent reinforced lithium disilicate ceramic laminates. One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent) was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick) under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE) of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B) and white (W) background readings was used for TP analysis, while chroma was calculated by the formula C*ab=(a*2+b*2)½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable.

  4. Digital Smile Design concept delineates the final potential result of crown lengthening and porcelain veneers to correct a gummy smile.

    Science.gov (United States)

    Trushkowsky, Richard; Arias, David Montalvo; David, Steven

    Prior to initiating any treatment, it is necessary to visualize the desired outcomes. It then becomes possible to formulate the steps required to achieve this result. Digital Smile Design (DSD) utilizes patient input and information gathered through diagnostic procedures to create an esthetic treatment scheme. In the case presented here, the NYUCD Esthetic Evaluation Form, intraoral and extraoral photographs, mounted diagnostic casts, physical examination, and radiographs were the diagnostic modalities. The gathered information served as a starting point for a wax-up and intraoral mock-up. This case report demonstrates how the DSD served as a template for crown lengthening procedures and design of the final porcelain veneer restorations.

  5. Time-dependent fracture probability of bilayer, lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation

    Science.gov (United States)

    Anusavice, Kenneth J.; Jadaan, Osama M.; Esquivel–Upshaw, Josephine

    2013-01-01

    Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. Objective The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6 mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Materials and methods Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Results Predicted fracture probabilities (Pf) for centrally-loaded 1,6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8 mm/0.8 mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4 mm/1.2 mm). Conclusion CARES/Life results support the proposed crown design and load orientation hypotheses. Significance The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. PMID:24060349

  6. Time-dependent fracture probability of bilayer, lithium-disilicate-based, glass-ceramic, molar crowns as a function of core/veneer thickness ratio and load orientation.

    Science.gov (United States)

    Anusavice, Kenneth J; Jadaan, Osama M; Esquivel-Upshaw, Josephine F

    2013-11-01

    Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8mm/0.8mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4mm/1.2mm). CARES/Life results support the proposed crown design and load orientation hypotheses. The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. Copyright © 2013 Academy of Dental Materials. All rights reserved.

  7. EFFECTS OF PRESS PRESSURE ON GLUE LINE THICKNESS AND PROPERTIES OF LAMINATED VENEER LUMBER GLUED WITH MELAMINE UREA FORMALDEHYDE ADHESIVE

    Directory of Open Access Journals (Sweden)

    Ramazan Kurt,

    2012-07-01

    Full Text Available Laminated veneer lumbers (LVLs were manufactured from half-round sliced I-214 hybrid poplar clone veneers with MUF adhesives using press pressures ranging from 2.5 to 15 kg cm-2. The results showed that the press pressures affected the glue line thickness (GLT and the physical and mechanical properties of the LVLs. Higher specific gravity (SG and mechanical properties, but lower GLT were developed as a result of using higher press pressures. The optimum press pressure was found to be 10 kg cm-2 in relation to GLT, SG, and mechanical properties. Significant linear correlations were found between GLT and mechanical properties. GLT can be used to determine the quality of wood bonding and may become a valuable tool for this purpose. Reliable data on the optimum GLT and press pressures can be used to design safe wood bonding applications in all aspects of wood based composites, as well as wood constructions when appropriate techniques are adopted to measure the GLT.

  8. Photostability and moisture uptake properties of wood veneers coated with a combination of thin sol-gel films and light stabilizers

    Science.gov (United States)

    Mandla A. Tshabalala; Ryan Libert; Christian M. Schaller

    2011-01-01

    In recent years, there has been increased interest in the use of inorganic UV blocking nanoparticles for photostabilization of wood surfaces. Photostability and moisture uptake properties of wood veneers coated with a combination of hybrid inorganic-organic thin sol-gel films and organic light stabilizers was investigated. The light stabilizers were applied by brushing...

  9. Effect of log soaking and the temperature of peeling on the properties of rotary-cut birch (Betula pendula Roth) veneer bonded with phenol-formaldehyde adhesive

    Science.gov (United States)

    Anti Rohumaa; Akio Yamamoto; Christopher G. Hunt; Charles R. Frihart; Mark Hughes; Jaan Kers

    2016-01-01

    Heating logs prior to peeling positively affects the surface properties of veneer as well as the wood-adhesive bond strength. However, the mechanism behind this increase in strength is not fully understood. The aim of the present study was to separate the influence of soaking temperature and peeling temperature on the physical surface properties and bonding quality....

  10. A randomized controlled clinical trial of 3-unit posterior zirconia-ceramic fixed dental prostheses (FDP) with layered or pressed veneering ceramics: 3-year results.

    Science.gov (United States)

    Naenni, Nadja; Bindl, Andreas; Sax, Caroline; Hämmerle, Christoph; Sailer, Irena

    2015-11-01

    The aim of the present pilot study was to test whether or not posterior zirconia-ceramic fixed dental prostheses (FDPs) with pressed veneering ceramic exhibit less chipping than FDPs with layered veneering ceramics. Forty patients (13 female, 27 male; mean age 54 years (range 26.1-80.7 years) in need of one maxillary or mandibular three-unit FDP in the second premolar or molar region were recruited and treated at two separate centers at the University of Zurich according to the same study protocol. The frameworks were made out of zirconia using a CAD/CAM system (Cerec Sirona, Bensheim, Germany). The patients were randomly assigned to either the test group (zirconia frameworks veneered with pressed ceramic; IPS e.max ZirPress, Ivoclar Vivadent AG, Schaan, Liechtenstein; n=20) or the control group (layered veneering ceramic; IPS e.max Ceram, Ivoclar Vivadent AG, Schaan, Liechtenstein; n=20). All FDPs were adhesively cemented and evaluated at baseline (i.e., cementation), at 6 months and at 1 and 3 years of clinical service. The survival of the reconstruction was recorded. The technical outcome was assessed using modified United States Public Health Services (USPHS) criteria. The biologic parameters analyzed at abutment teeth and analogous non-restored teeth included probing pocket depth (PPD), plaque control record (PCR), bleeding on probing (BOP), and tooth vitality (CO2). Data was descriptively analyzed and survival was calculated using Kaplan-Meier statistics. 36 patients (25 female, 11 male; mean age 52.3 years) with 18 test and 18 control FDPs were examined after a mean follow-up of 36 months (95% CI: 32.6-39.1 months). Comparison of groups was done by Crosstabulation showing even distribution of the respective restored teeth amidst the groups. Survival rate was 100% for both test and control FDPs. Chipping of the veneering ceramic tended to occur more frequently in test (n=8; 40%) than in control (n=4; 20%) FDPs, albeit not significantly (p=0.3). No further

  11. Main Clinical Outcomes of Feldspathic Porcelain and Glass-Ceramic Laminate Veneers: A Systematic Review and Meta-Analysis of Survival and Complication Rates.

    Science.gov (United States)

    Morimoto, Susana; Albanesi, Rafael Borges; Sesma, Newton; Agra, Carlos Martins; Braga, Mariana Minatel

    2016-01-01

    The aim of this study was to perform a systematic review and meta-analysis based on clinical trials that evaluated the main outcomes of glass-ceramic and feldspathic porcelain laminate veneers. A systematic search was carried out in Cochrane and PubMed databases. From the selected studies, the survival rates for porcelain and glass-ceramic veneers were extracted, as were complication rates of clinical outcomes: debonding, fracture/chipping, secondary caries, endodontic problems, severe marginal discoloration, and influence of incisal coverage and enamel/dentin preparation. The Cochran Q test and the I(2) statistic were used to evaluate heterogeneity. Out of the 899 articles initially identified, 13 were included for analysis. Metaregression analysis showed that the types of ceramics and follow-up periods had no influence on failure rate. The estimated overall cumulative survival rate was 89% (95% CI: 84% to 94%) in a median follow-up period of 9 years. The estimated survival for glass-ceramic was 94% (95% CI: 87% to 100%), and for feldspathic porcelain veneers, 87% (95% CI: 82% to 93%). The meta-analysis showed rates for the following events: debonding: 2% (95% CI: 1% to 4%); fracture/chipping: 4% (95% CI: 3% to 6%); secondary caries: 1% (95% CI: 0% to 3%); severe marginal discoloration: 2% (95% CI: 1% to 10%); endodontic problems: 2% (95% CI: 1% to 3%); and incisal coverage odds ratio: 1.25 (95% CI: 0.33 to 4.73). It was not possible to perform meta-analysis of the influence of enamel/dentin preparation on failure rates. Glass-ceramic and porcelain laminate veneers have high survival rates. Fracture/ chipping was the most frequent complication, providing evidence that ceramic veneers are a safe treatment option that preserve tooth structure.

  12. Secondary overprinting of S-Se-Te signatures in the Earth's mantle: Implications for the Late Veneer

    Science.gov (United States)

    Koenig, S.; Luguet, A.; Lorand, J.; Pearson, D.

    2013-12-01

    Sulphur, Selenium and Tellurium are both chalcophile and highly siderophile elements (HSE) with near-chondritic ratios and absolute abundances in the terrestrial mantle that exceed those predicted by core-mantle differentiation[1]. These 'excess' HSE abundances have been attributed to addition of ca. 0.5% of chondrite-like material that hit the Earth in its accretionary stage between 4 to 3.8 billion years ago after core-mantle differentiation (Late Veneer[2]). Therefore, like other HSE, S, Se and Te are considered potential tracers for the composition of the Late Veneer, provided that their bulk silicate Earth abundances are properly constrained. In contrast to ca. 250 ppm S, Se and Te are ultra-trace elements in the terrestrial mantle. Like all HSE, they are furthermore controlled by base metal sulphides (BMS) and micrometric platinum group minerals (PGMs)[3]. This strong control exerted by the host mineralogy and petrology on the S-Se-Te systematics at both the micro-scale and the whole-rock scale makes detailed mineralogical and petrological studies of BMS and PGM a pre-requisite to fully understand and accurately interpret the whole-rock signatures. Here we combine in-situ sulphide data and detailed mineralogical observations with whole-rock S-Se-Te-HSE signatures of both lherzolites and harburgites from different geodynamic settings. We demonstrate that the near-chondritic Se and Te signature of 'fertile' mantle rocks (Se/Te ≈9×5) is not a primitive signature of the Earth's mantle, but rather reflects strong enrichment in metasomatic HSE host phases, which erased previous pristine signatures. Consequently, current attempts to identify a potential Late Veneer composition are seriously flawed because, neither refertilisation/metasomatism nor true melt depletion (e.g. harzburgitic residues) have been taken into account for the Primitive Upper Mantle composition estimate[4]. Our combined whole rock and in-situ sulphide data indicate a refertilisation trend

  13. Effect of core ceramic grinding on fracture behaviour of bilayered zirconia veneering ceramic systems under two loading schemes.

    Science.gov (United States)

    Jian, Yu-Tao; Tang, Tian-Yu; Swain, Michael V; Wang, Xiao-Dong; Zhao, Ke

    2016-12-01

    The aim of this in vitro study was to evaluate the effect of core ceramic grinding on the fracture behaviour of bilayered zirconia under two loading schemes. Interfacial surfaces of sandblasted zirconia disks (A) were ground with 80 (B), 120 (C) and 220 (D) grit diamond discs, respectively. Surface roughness and topographic analysis were performed using a confocal scanning laser microscope (CSLM) and a scanning electron microscopy (SEM). Relative monoclinic content was evaluated using X-ray diffraction analysis (XRD) then reevaluated after simulated veneer firing. Biaxial fracture strength (σ) and Weibull modulus (m) were calculated either with core in compression (subgroup Ac-Dc) or in tension (subgroup At-Dt). Facture surfaces were examined by SEM and energy dispersive X-ray spectroscopy (EDS). Maximum tensile stress at fracture was estimated by finite element analysis. Statistical data analysis was performed using Kruskal-Wallis and one-way ANOVA at a significance level of 0.05. As grit size of the diamond disc increased, zirconia surface roughness decreased (pgrinding. No difference in initial (p=0.519 for subgroups Ac-Dc) and final fracture strength (p=0.699 for subgroups Ac-Dc; p=0.328 for subgroups At-Dt) was found among the four groups for both loading schemes. While coarse grinding slightly increased final fracture strength reliability (m) for subgroups Ac-Dc. Two different modes of fracture were observed according to which material was on the bottom surface. Components of the liner porcelain remained on the zirconia surface after fracture for all groups. Technician grinding changed surface topography of zirconia ceramic material, but was not detrimental to the bilayered system strength after veneer application. Coarse grinding slightly improved the fracture strength reliability of the bilayered system tested with core in compression. It is recommended that veneering porcelain be applied directly after routine lab grinding of zirconia ceramic, and its

  14. High pressure low temperature hot pressing method for producing a zirconium carbide ceramic

    Science.gov (United States)

    Cockeram, Brian V.

    2017-01-10

    A method for producing monolithic Zirconium Carbide (ZrC) is described. The method includes raising a pressure applied to a ZrC powder until a final pressure of greater than 40 MPa is reached; and raising a temperature of the ZrC powder until a final temperature of less than 2200.degree. C. is reached.

  15. Ionic drift velocity measurement on hot-pressed Ag ion conducting ...

    Indian Academy of Sciences (India)

    Shri Shankaracharya Institute of Professional Management & Technology, Raipur 492 015, India. MS received 29 October 2014; accepted 14 August 2015. Abstract. Ionic drift ..... Chandra S 1981 Superionic solids—principle and applications.

  16. Electronic transport properties of hot-pressed B/sub 6/Si

    International Nuclear Information System (INIS)

    Wood, C.; Emin, D.; Feigelson, R.S.; Mackinnon, I.D.R.

    1987-01-01

    Measurements of the electrical conductivity, Seebeck coefficient and Hall mobility from --300 K to --1300 K have been carried out on multiphase hotpressed samples of the nominal composition B/sub 6/Si. In all samples the conductivity and the p-type Seebeck coefficient both increase smoothly with increasing temperature. By themselves, these facts suggest small-polaronic hopping between inequivalent sites. The measured Hall mobilities are always low, but vary in sign. A possible explanation is offered for this anomalous behavior

  17. Room Temperature Elastic Moduli and Vickers Hardness of Hot-Pressed LLZO Cubic Garnet

    Science.gov (United States)

    2012-01-01

    4140-steel [29] as well as composites such as Al/Al2O3 [30] and Ni– YSZ cermets [27]. The RUS apparatus used in this study consists of a computer...Microstructure and lattice parameter of LLZO specimens In this study , the LLZO microstructure was observed on a (i) fracture surface of LLZO-01 (Fig. 1a) and... study are consistent with the trend (Eq. 2) of a power law decrease in mechanical properties with increasing lattice parameter observed for other garnet

  18. Thermal conductivity and thermal expansion of hot-pressed trisodium uranate (Na3UO4)

    International Nuclear Information System (INIS)

    Hofman, G.L.; Bottcher, J.H.; Buzzell, J.A.; Schwartzenberger, G.M.

    1986-01-01

    Thermal conductivity and thermal expansion of Na 3 UO 4 prepared by two different reaction processes were determined over a temperature range of 20-1000 0 C. Compositional differences in the samples resulting from the different reaction processes have a pronounced effect on thermal expansion and on thermal conductivity below 500 0 C. Above 500 0 C, these compositional differences in the thermal conductivities decrease. (orig.)

  19. Creep and threshold tension in aluminum-matrix composite with short fibers obtained by hot pressing

    International Nuclear Information System (INIS)

    Moreno, M.F; Gonzalez Oliver, C.R.J

    2004-01-01

    An aluminum matrix composite reinforced with 5% vol. of short fibers of silicon carbide and un-reinforced matrix, produced by pulvimetallurgy (PM) were studied using creep compression at different deformation speeds and in the range of 300 o C to 500 o C. The creep curve of both materials showed the typical behavior of a material with threshold tension τ 0 ; with an estimate value of 6.31MPa for the matrix at 400 o C and 6.43, 8.76 and 11MPa at 350, 400 and 450 o C respectively for the composite. The τ 0 was shown to obey a thermally activated mechanism whose energy is about 17 kJ/mol. Nanometric particles of aluminum oxide were scattered throughout the matrix and the composite, arising from the inevitable film of oxides and hydroxides formed in the metallic powder. The exponent of power-law creep occurs in the values of n = 4.3 to 4.85 by reducing the tension to an effective value τ-τ 0 , corresponding to a drilling fault in both materials. In the composite, the activation energy was estimated at 167 to 125 kJ/mol, close to the self- diffusion enthalpy of the pure aluminum at 143.4 kJ/mol so that the creep process in the composite is controlled exclusively by the deformation of the matrix (CW)

  20. W–steel and W–WC–steel composites and FGMs produced by hot pressing

    Czech Academy of Sciences Publication Activity Database

    Matějíček, Jiří; Boldyryeva, Hanna; Brožek, Vlastimil; Sachr, P.; Chráska, Tomáš; Pala, Zdeněk

    2015-01-01

    Roč. 100, November (2015), s. 364-370 ISSN 0920-3796 R&D Projects: GA ČR(CZ) GAP108/12/1872 EU Projects: European Commission(DE) WP11-MAT-WWALLOY Institutional support: RVO:61389021 Keywords : FGM * Composite * Tungsten * Steel * Fusion reactor material Subject RIV: JF - Nuclear Energetics OBOR OECD: Nuclear related engineering Impact factor: 1.301, year: 2015 http://www.sciencedirect.com/science/article/pii/S0920379615302106

  1. Formability of fiber-reinforced thermoplastics in hot press forming process based on friction properties

    NARCIS (Netherlands)

    Sachs, Ulrich; Haanappel, Sebastiaan; Rietman, Bert; ten Thije, R.H.W.; Akkerman, Remko

    2013-01-01

    In this paper an advanced solid state cladding process, based on Friction Stir Welding, is presented. The Friction Surface Cladding (FSC) technology enables the deposition of a solid-state coating using filler material on a substrate with good metallurgical bonding. A relatively soft AA1050 filler

  2. Shear Bond Strengths between Three Different Yttria-Stabilized Zirconia Dental Materials and Veneering Ceramic and Their Susceptibility to Autoclave Induced Low-Temperature Degradation

    Directory of Open Access Journals (Sweden)

    Manoti Sehgal

    2016-01-01

    Full Text Available A study was undertaken to evaluate the effect of artificial aging through steam and thermal treatment as influencing the shear bond strength between three different commercially available zirconia core materials, namely, Upcera, Ziecon, and Cercon, layered with VITA VM9 veneering ceramic using Universal Testing Machine. The mode of failure between zirconia and ceramic was further analyzed as adhesive, cohesive, or mixed using stereomicroscope. X-ray diffraction and SEM (scanning electron microscope analysis were done to estimate the phase transformation (m-phase fraction and surface grain size of zirconia particles, respectively. The purpose of this study was to simulate the clinical environment by artificial aging through steam and thermal treatment so as the clinical function and nature of the bond between zirconia and veneering material as in a clinical trial of 15 years could be evaluated.

  3. Influence of a thin veneer of low-hydraulic-conductivity sediment on modelled exchange between river water and groundwater in response to induced infiltration

    Science.gov (United States)

    Rosenberry, Donald O.; Healy, Richard W.

    2012-01-01

    A thin layer of fine-grained sediment commonly is deposited at the sediment–water interface of streams and rivers during low-flow conditions, and may hinder exchange at the sediment–water interface similar to that observed at many riverbank-filtration (RBF) sites. Results from a numerical groundwater-flow model indicate that a low-permeability veneer reduces the contribution of river water to a pumping well in a riparian aquifer to various degrees, depending on simulated hydraulic gradients, hydrogeological properties, and pumping conditions. Seepage of river water is reduced by 5–10% when a 2-cm thick, low-permeability veneer is present on the bed surface. Increasing thickness of the low-permeability layer to 0·1 m has little effect on distribution of seepage or percentage contribution from the river to the pumping well. A three-orders-of-magnitude reduction in hydraulic conductivity of the veneer is required to reduce seepage from the river to the extent typically associated with clogging at RBF sites. This degree of reduction is much larger than field-measured values that were on the order of a factor of 20–25. Over 90% of seepage occurs within 12 m of the shoreline closest to the pumping well for most simulations. Virtually no seepage occurs through the thalweg near the shoreline opposite the pumping well, although no low-permeability sediment was simulated for the thalweg. These results are relevant to natural settings that favour formation of a substantial, low-permeability sediment veneer, as well as central-pivot irrigation systems, and municipal water supplies where river seepage is induced via pumping wells

  4. [Effect of repeated sintering and variations in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers].

    Science.gov (United States)

    Cui, Huang; Jia, Yu; Shaofeng, Meng; Biyun, Gao

    2017-08-01

    Objective The aim of this study is to evaluate the effect of repeated sintering and variation in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers. Methods A total of 24 computer aided design and computer aided manufacturing (CAD/CAM) veneers was fabricated using the IPS e.max-CAD LS2 and then randomly divided into four groups (S0, S1, S2, S3; n=6). Each group was sintered 0, 1, 2, 3 times individually according to the manufacturer's recommendation. The color parameters (L, C, H, a, b values) of all the specimens were measured by a Vita easyshade dental colorimeter. The results were statistically analyzed using the SAS 9.1.3 software for MANOVA and LSD. Subsequently, the microstructures of the intersecting surfaces of the specimens were observed by scanning electron microscopy (SEM). Results After repeated sintering, the L value significantly decreased (P<0.05). For the C and b values, statistical differences were observed among the groups except between S2 and S3. SEM results showed that the interlocking microstructures of rod-shaped Li₂Si₂O₅ crystals became more compact when the number of sintering times was increased. Conclusion Repeated sintering exhibited significant influence on the color of the IPS e.max-CAD LS2 veneers.

  5. Evaluation of the color durability of acrylic resin veneer materials after immersion in common beverages at different time intervals: A spectrophotometric study.

    Science.gov (United States)

    Kohli, Shivani; Bhatia, Shekhar

    2015-01-01

    Proper function, esthetics, and cost are the prime factors to be considered while selecting bridge veneering materials. The purpose of the study is to evaluate color durability of acrylic veneer materials after immersion in common beverages at different time intervals. Spectrophotometer was used for taking color measurements based on the transmission of light through the specimens made of the selected materials which were Tooth moulding powder (DPI) and Acrylux (Ruthinium). Thirty specimens of standardized dimensions were prepared from each material. The specimens were divided into three groups of 10 each. One group of each material was immersed in tea (TajMahal) and another group of each material in cola (Pepsi) as the staining solutions. The remaining group of 10 from each material served as control and was stored in distilled water. Color measurements were obtained pre-immersion, and after 1, 15, and 30 days of immersion. Tooth moulding powder displayed better color durability than Acrylux over the 1 month immersion period in both staining solutions. Tea resulted in more discoloration compared to cola (Pepsi). The difference in the color durability of Acrylux and Tooth moulding powder may be attributed to the differences in the composition of tested resin veneering materials, i.e. their polar properties, which contribute to the absorption of staining solution, and the different brands and the strengths of the solutions.

  6. Evaluation of the color durability of acrylic resin veneer materials after immersion in common beverages at different time intervals: A spectrophotometric study

    Directory of Open Access Journals (Sweden)

    Shivani Kohli

    2015-06-01

    Full Text Available Background: Proper function, esthetics, and cost are the prime factors to be considered while selecting bridge veneering materials. The purpose of the study is to evaluate color durability of acrylic veneer materials after immersion in common beverages at different time intervals. Methods: Spectrophotometer was used for taking color measurements based on the transmission of light through the specimens made of the selected materials which were Tooth moulding powder (DPI and Acrylux (Ruthinium. Thirty specimens of standardized dimensions were prepared from each material. The specimens were divided into three groups of 10 each. One group of each material was immersed in tea (TajMahal and another group of each material in cola (Pepsi as the staining solutions. The remaining group of 10 from each material served as control and was stored in distilled water. Color measurements were obtained pre-immersion, and after 1, 15, and 30 days of immersion. Results: Tooth moulding powder displayed better color durability than Acrylux over the 1 month immersion period in both staining solutions. Tea resulted in more discoloration compared to cola (Pepsi. Conclusion: The difference in the color durability of Acrylux and Tooth moulding powder may be attributed to the differences in the composition of tested resin veneering materials, i.e. their polar properties, which contribute to the absorption of staining solution, and the different brands and the strengths of the solutions.

  7. Effect of bleaching and repolishing procedures on coffee and tea stain removal from three anterior composite veneering materials.

    Science.gov (United States)

    Türkün, L Sebnem; Türkün, Murat

    2004-01-01

    Discolored teeth can be treated with resin veneers, but their color changes when confronted with staining solutions. Polishing procedures can provide a remedy for highly stained composites, but they tend to remove some materials as well. However, bleaching procedures are an effective, nondestructive method for solving the problem. The aim of this study was to compare the color change of three veneer composites exposed to staining solutions and to evaluate the effectiveness of a 15% hydrogen peroxide bleaching agent and three polishing systems to remove the stain. Forty-five disks (12 x 2 mm) each of Clearfil ST (Kuraray Co. Ltd., Osaka, Japan), Esthet-X (Dentsply/Caulk, Milford DE, USA), and Filtek A110 (3M ESPE, St. Paul, MN, USA) were prepared. The specimens were polished with Sof-Lex (3M ESPE), Enhance (Dentsply/Caulk), or PoGo (Dentsply/Caulk). Five specimens for each material-polishing system combination were immersed in coffee (Nescafe Classic, Nestle SA, Vevey, Switzerland) or tea (Earl Grey, Lipton, Blackfriars-London, England) for 7 days. The remaining disks were stored in water. Color measurements were made with a spectrophotometer (X-Rite Seroice SP78, Loaner, Köln, Germany) at baseline; after 1, 3, 5, and 7 days; and after bleaching and repolishing. After 1 week, one side of the specimens was bleached with Illuminé-office (Dentsply De Trey GmbH, Konstanz, Germany) for 1 hour, and the other side was repolished for 30 seconds. All comparisons of color change for the polishing systems, times, and staining solutions were subjected to repeated measurements of analysis of variance. Paired t-test was used to examine whether significant color differences (deltaE*) occurred during immersion at the specified time intervals (p < or = .05). Filtek A110 was the least stained resin composite. Its color remained under a deltaE* value of 2 during the study. Clearfil ST exhibited the most color change after 1 week. All specimens polished with Enhance showed less

  8. WE-NET. Substask 4. Development of hydrogen production technologies; 1998 nendo suiso riyo kokusai clean energy system gijutsu (WE-NET). 4. Suiso seizo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    Under the hydrogen-utilizing international clean energy system technology project WE-NET (World Energy NET Work), researches were conducted aiming at the establishment of a hydrogen production technology through electrolysis of polymer electrolyte solution. In fiscal 1998, element technologies were developed for the development of high-efficiency/large-capacity water electrolyzing plants using electrodeless deposition and hot pressing, research and investigation of optimum operating conditions were conducted, and a service plant conceptual design and a polymer electrolytic membrane were developed. In addition, literature was searched for the current state of ion exchange membranes and water electrolysis, both indispensable for the hydrogen production technology discussed in this paper. In the field of lamination of large cells (electrode surface:2500cm{sup 2}), an excellent energy efficiency level exceeding 90% set as the target for a large laminated cell performance test was achieved - 92.6% by electrodeless deposition and 94.4% by hot pressing. As for polymer membranes capable of resisting high temperatures, a membrane with an ionic conductivity of 0.066S/cm at 200 degrees C was newly developed. (NEDO)

  9. Fracture Resistance of Ceramic Laminate Veneers Bonded to Teeth with Class V Composite Fillings after Cyclic Loading

    Directory of Open Access Journals (Sweden)

    Leyla Sadighpour

    2018-01-01

    Full Text Available Purpose. Porcelain laminate veneers (PLVs are sometimes required to be used for teeth with composite fillings. This study examined the fracture strength of PLVs bonded to the teeth restored with different sizes of class V composite fillings. Materials and Methods. Thirty-six maxillary central incisors were divided into three groups (n=12: intact teeth (control and teeth with class V composite fillings of one-third or two-thirds of the crown height (small or large group, resp.. PLVs were made by using IPS e.max and bonded with a resin cement (RelyX Unicem. Fracture resistance (N was measured after cyclic loading (1 × 106 cycles, 1.2 Hz. For statistical analyses, one-way ANOVA and Tukey test were used (α=0.05. Results. There was a significant difference between the mean failure loads of the test groups (P=0.004, with the Tukey-HSD test showing lower failure loads in the large-composite group compared to the control (P=0.02 or small group (P=0.05. The control and small-composite groups achieved comparable results (P>0.05. Conclusions. Failure loads of PLVs bonded to intact teeth and to teeth with small class V composite fillings were not significantly different. However, extensive composite fillings could compromise the bonding of PLVs.

  10. Remote monitoring of air movement through a high-rise, brick veneer and steel-stud wall system

    Energy Technology Data Exchange (ETDEWEB)

    Niemeyer, T.A.; Genge, G.R. [GRG Building Consultants Inc. (Canada)

    2011-07-01

    Since the early 20th century, research on building enclosures has been going on in the form of field investigations and laboratory testing, but real-time monitoring of buildings is relatively new. Compact sensors and programmable data logging equipment have allowed thorough, real-time trend analysis of occupied buildings. This paper discusses the remote monitoring of air movement using a high-rise brick veneer and steel-stud wall system. This equipment was installed across the exterior wall assembly. Temperature and air moisture content within the stud cavity and outdoor to indoor air pressure difference was measured across the entire assembly and in series across the various components of the wall. For outdoor conditions, local airport weather records were used. Comparing collected temperature data and the theoretical thermal model, it was concluded that there was air leakage. From the overall project, lessons learned included that is was important to minimize discomfort, both in aesthetics and in the number of requests for access to homes for analyses.

  11. Effect of light-curing method and indirect veneering materials on the Knoop hardness of a resin cement

    Directory of Open Access Journals (Sweden)

    Nelson Tetsu Iriyama

    2009-06-01

    Full Text Available This study evaluated the Knoop hardness of a dual-cured resin cement (Rely-X ARC activated solely by chemical reaction (control group or by chemical / physical mode, light-cured through a 1.5 mm thick ceramic (HeraCeram or composite (Artglass disc. Light curing was carried out using conventional halogen light (XL2500 for 40 s (QTH; light emitting diodes (Ultrablue Is for 40 s (LED; and Xenon plasma arc (Apollo 95E for 3 s (PAC. Bovine incisors had their buccal face flattened and hybridized. On this surface a rubber mold (5 mm in diameter and 1 mm in height was bulk filled with the resin cement. A polyester strip was seated for direct light curing or through the discs of veneering materials. After dry storage in the dark (24 h 37°C, the samples (n = 5 were sectioned for hardness (KHN measurements, taken in a microhardness tester (50 gF load 15 s. The data were statistically analyzed by ANOVA and Tukey's test (α = 0.05. The cement presented higher Knoop hardness values with Artglass for QTH and LED, compared to HeraCeram. The control group and the PAC/Artglass group showed lower hardness values compared to the groups light-cured with QTH and LED. PAC/HeraCeram resulted in the worst combination for cement hardness values.

  12. Retrospective Study of Retention of Stainless Steel Crowns and Pre-veneered Crowns on Primary Anterior Teeth.

    Science.gov (United States)

    Lopez-Loverich, Angela M; Garcia, Maria Minerva; Donly, Kevin J

    2015-01-01

    The purpose of this retrospective chart review was to explore the retention of anterior pre-veneered stainless steel crowns (NuSmile) and conventional stainless steel crowns (3M ESPE) placed on primary anterior teeth. Records for children were reviewed over four years using the electronic record system axiUm. Data collected included child's age at time of crown placement, date of placement, tooth number, type of crown, patient behavior, treatment environment, provider type, crown presence, absence, and cementation success or failure at subsequent recall visits. A total of 637 anterior crowns in children treated with either or both crown types met this study's inclusion criteria. Of these crowns, 483 were NuSmile Signature crowns and 154 were stainless steel crowns. There was a nine percent failure rate for the NuSmile Signature crowns and a seven percent failure rate for the stainless steel crowns. There was no statistically significant difference in crown retention rates between the two groups (P<0.05). A full-coverage restoration that can follow the lifespan of the primary anterior dentition in high-risk children is needed. The results from this study indicate good crown retention rates for both crown types with no statistically significant difference between them (P<0.05).

  13. The production and characterization of Ptfe bonded Nd-Fe-B magnets

    International Nuclear Information System (INIS)

    Mokal, B.; Williams, A.J.; Hay, J.N.; Harris, I.R.

    1996-01-01

    A study of the processing and characteristics of PTFE bonded Nd Fe B magnets has been carried out. PTFE was used because of its low coefficient of friction, thus enabling its flow between the particles of Nd Fe B powder. PTFE also increases the resistance to corrosion of the magnet. In these investigations, the production of bonded magnets by cold compaction and by hot processing (HP) of MQ powders using PTFE as the binder was investigated . Magnetic, microstructural, and mechanical properties were investigated and are presented together with a correlation with the different processing techniques used. The corrosion behaviour of the hot pressed magnets was also investigated. These studies could lead to the development of simpler and more effective processing routes for the production of bonded magnets. (author)

  14. Dental implant suprastructures using cobalt-chromium alloy compared with gold alloy framework veneered with ceramic or acrylic resin: a retrospective cohort study up to 18 years.

    Science.gov (United States)

    Teigen, Kyrre; Jokstad, Asbjørn

    2012-07-01

    An association between the long-term success and survival of implant-supported prostheses as a function of biomaterial combinations has not been established. The use of cast cobalt-chromium for the suprastructure framework may be an alternative to the conventional approach of using type 3 gold alloys. A retrospective chart audit of all patients who had received implant-supported fixed dental prostheses (FDP) before 1996 was identified in a private practice clinic. Data were recorded for FDPs made from four combinations of alloy frameworks and veneering material, i.e. type 3 gold and cobalt-chromium with ceramic or prefabricated acrylic teeth. The extracted data from the charts were subjected to explorative statistical tests including Kaplan-Meier survival analyses. Patients (n=198) with 270 short and extensive FDPs supported entirely by 1117 implants were identified. The average follow-up observation periods varied between 4 and 220 months, with an average of 120 months. The success and survival, as well as event rates and types of biological and technical complications, were similar for implant-supported FDPs using cobalt-chromium and type 3 gold alloy frameworks veneered with ceramics or prefabricated acrylic teeth. An influence of the suprastructure biomaterial combination on the clinical performance of the individual supporting implants could not be established. Implant-supported FDPs made from type 3 gold or cobalt-chromium frameworks and veneered with ceramic or prefabricated acrylic teeth demonstrate comparable clinical performance. The biomaterial combinations do not appear to influence the success or survival of the individual implants. © 2011 John Wiley & Sons A/S.

  15. INFLUENCE OF SILANE HEAT TREATMENT ON THE TENSILE BOND STRENGTH BETWEEN EX-3 SYNTHETIC VENEERING PORCELAIN AND COMPOSITE RESIN USING FIVE DIFFERENT ACTIVATION TEMPERATURES

    Directory of Open Access Journals (Sweden)

    Spartak Yanakiev

    2017-02-01

    Full Text Available Purpose: The purpose of the present study is to assess the effect of five different silane activation temperatures and eight activation methods on the tensile bond strength between one veneering porcelain and one composite resin material. Material and methods: A total of 81 ceramic rods were made of EX-3 veneering ceramic (Kuraray Noritake Dental, Japan. Sintered ceramic bars were grinded with diamond disks to size 10x2x2mm ± 0,05mm. The front part of each bar was polished. After ultrasonic cleaning in distilled water, the specimens were divided into nine groups. Silane was activated with air at room temperature, 38º С, 50º С, 100º С, 120º С using a custom made blow drier. In a silicone mold, a composite resin Z250 (3М ESPE, St. Paul, USA was condensed toward the bond ceramic surface. A total of 81 specimens approximately 2,0 cm long were prepared for tensile bond testing. One way ANOVA, followed by Bonferroni and Games-Howell tests were used for statistical analysis. Results: The lowest tensile bond strength was observed in the control group (3,51MPa. Group 2 yielded the highest bond strength among all groups (19,54MPa. Silane heat treatment enhanced the bond strength for all treatment methods. Within the polished specimens, the highest bond strength was yielded with warm air at 120ºС (11,31MPa. Conclusion: The most effective method for bonding Z250 composite resin to EX-3 veneering ceramic includes HF etching, silane, and adhesive resin. The most effective heat treatment method for bonding is hot air at 120ºС.

  16. Surface photo-discoloration and degradation of dyed wood veneer exposed to different wavelengths of artificial light

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States); Shao, Lingmin [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Gao, Jianmin, E-mail: jmgao@bjfu.edu.cn [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Guo, Hongwu, E-mail: hwg5052@163.com [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Chen, Yao [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, Beijing 100083 (China); Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083 (China); MOE Engineering Research Center of Forestry Biomass Materials and Bioenergy, Beijing Forestry University, Beijing 100083 (China); Cheng, Qingzheng; Via, Brian K. [Forest Products Development Center, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL 36830 (United States)

    2015-03-15

    Highlights: • Investigate the selective absorption of different wavelengths of UV–vis light by dyed wood chromophores. • Identify connection between light wavelengths and surface color changes and chemical structure degradation. • Study hypochromic effect based on surface reflectance and K/S absorption changes during UV–vis irradiation. - Abstract: The surface of dyed wood is prone to discoloration when exposed to light irradiation which significantly decreases its decorative effect and shortens its service life. The influence of light wavelength exposure to the surface of dyed wood was investigated to study the effect on discoloration and degradation. Acid Blue V and Acid Red GR dyed wood veneers were subjected to light exposure with different wavelengths from the UV to visible region (254–420 nm). Results showed that the surface discoloration of dyed wood was linearly related to lignin concentration and dyes degradation and the consequent transformation of chromophoric groups such as aromatic (C=C) and carbonyl (C=O) through methoxy reaction. The dyes, lignin and some active constituents were degraded severely, even at short exposures. Acid Blue V dyed wood exhibited greater discoloration than the Acid Red GR treatment. The reflectance and K/S absorption curve showed a hypochromic effect on the dyed wood surface. The dyes and wood chemical structure played a complex and combined role on the selective absorption of different wavelengths of light. The color change rate was apparent with 254 nm exposure in the initial stages, but a greater discoloration rate occurred on the samples irradiated at 313 and 340 nm than at 254 and 420 nm with the time prolonged. The degradation rate and degree of discoloration correlated well with the light energy and wavelength.

  17. Tracing metal-silicate segregation and late veneer in the Earth and the ureilite parent body with palladium stable isotopes

    Science.gov (United States)

    Creech, J. B.; Moynier, F.; Bizzarro, M.

    2017-11-01

    Stable isotope studies of highly siderophile elements (HSE) have the potential to yield valuable insights into a range of geological processes. In particular, the strong partitioning of these elements into metal over silicates may lead to stable isotope fractionation during metal-silicate segregation, making them sensitive tracers of planetary differentiation processes. We present the first techniques for the precise determination of palladium stable isotopes by MC-ICPMS using a 106Pd-110Pd double-spike to correct for instrumental mass fractionation. Results are expressed as the per mil (‰) difference in the 106Pd/105Pd ratio (δ106Pd) relative to an in-house solution standard (Pd_IPGP) in the absence of a certified Pd isotopic standard. Repeated analyses of the Pd isotopic composition of the chondrite Allende demonstrate the external reproducibility of the technique of ±0.032‰ on δ106Pd. Using these techniques, we have analysed Pd stable isotopes from a range of terrestrial and extraterrestrial samples. We find that chondrites define a mean δ106Pdchondrite = -0.19 ± 0.05‰. Ureilites reveal a weak trend towards heavier δ106Pd with decreasing Pd content, similar to recent findings based on Pt stable isotopes (Creech et al., 2017), although fractionation of Pd isotopes is significantly less than for Pt, possibly related to its weaker metal-silicate partitioning behaviour and the limited field shift effect. Terrestrial mantle samples have a mean δ106Pdmantle = -0.182 ± 0.130‰, which is consistent with a late-veneer of chondritic material after core formation.

  18. Shear bond strength of porcelain laminate veneers to enamel, dentine and enamel-dentine complex bonded with different adhesive luting systems.

    Science.gov (United States)

    Öztürk, Elif; Bolay, Şükran; Hickel, Reinhard; Ilie, Nicoleta

    2013-02-01

    The aim of this study was to evaluate the shear bond strength of porcelain laminate veneers to 3 different surfaces by means of enamel, dentine, and enamel-dentine complex. One hundred thirty-five extracted human maxillary central teeth were used, and the teeth were randomly divided into 9 groups (n=15). The teeth were prepared with 3 different levels for bonding surfaces of enamel (E), dentine (D), and enamel-dentine complex (E-D). Porcelain discs (IPS e.max Press, Ivoclar Vivadent) of 2mm in thickness and 4mm in diameter were luted to the tooth surfaces by using 2 light-curing (RelyX Veneer [RV], 3M ESPE; Variolink Veneer [VV], Ivoclar Vivadent) and a dual-curing (Variolink II [V2], Ivoclar Vivadent) adhesive systems according to the manufacturers' instructions. Shear bond strength test was performed in a universal testing machine at 0.5mm/min until bonding failure. Failure modes were determined under a stereomicroscope, and fracture surfaces were evaluated with a scanning electron microscope. The data were statistically analysed (SPSS 17.0) (p=0.05). Group RV-D exhibited the lowest bond strength value (5.42±6.6MPa). There was statistically no difference among RV-D, V2-D (13.78±8.8MPa) and VV-D (13.84±6.2MPa) groups (p>0.05). Group VV-E exhibited the highest bond strength value (24.76±8.8MPa). The type of tooth structure affected the shear bond strength of the porcelain laminate veneers to the 3 different types of tooth structures (enamel, dentine, and enamel-dentine complex). When dentine exposure is necessary during preparation, enough sound enamel must be protected as much as possible to maintain a good bonding; to obtain maximum bond strength, preparation margins should be on sound enamel. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Three-year clinical follow-up of posterior teeth restored with leucite-reinforced ips empress onlays and partial veneer crowns.

    Science.gov (United States)

    Murgueitio, Rafael; Bernal, Guillermo

    2012-07-01

    The aim of this study was to analyze the survival rate and failure mode of IPS leucite-reinforced ceramic onlays and partial veneer crowns regarding thickness under the following clinical conditions: vital versus nonvital teeth, tooth location, and type of opposing dentition. Teeth were prepared according to established guidelines for ceramic onlays and partial veneer crowns. Before cementation, the restorations were measured for occlusal thickness at the central fossa, mesial, and distal marginal ridges, and functional and nonfunctional cusps. A total of 210 ceramic restorations were cemented in 99 patients within a mean observation period of 2.9 ± 1.89 years. The mode of failure was classified and evaluated as (1) adhesive, (2) cohesive, (3) combined failure, (4) decementation, (5) tooth sensitivity, and (6) pulpal necrosis. Kaplan, log-rank, and Cox regression tests were used for statistical analysis. The failure rate was 3.33% (7/210). Increased material thickness produced less probability of failures. Vital teeth were less likely to fail than nonvital teeth. Second molars were five times more susceptible to failure than first molars. Tooth sensitivity postcementation and the type of opposing dentition were not statistically significant in this study. In this study, thickness of the restorations, tooth vitality, and location of teeth in the dental arch influenced restoration failures. © 2012 by the American College of Prosthodontists.

  20. [Wear intensity and surface roughness of microhybrid composite and ceramic occlusal veneers on premolars after the thermocycling and cyclic mechanical loading tests].

    Science.gov (United States)

    Zhang, H Y; Jiang, T; Cheng, M X; Zhang, Y W

    2018-02-18

    To evaluate the wear intensity and surface roughness of occlusal veneers on premolars made of microhybrid composite resin or two kinds of ceramics in vitro after the thermocycling and cyclic mechanical loading tests. In the study,24 fresh extracted human premolars without root canal treatment were prepared (cusps reduction of 1.5 mm in thickness to simulate middle to severe tooth wear, the inclinations of cusps were 20°). The prepared teeth were restored with occlusal veneers made of three different materials: microhybrid composite, heat-pressed lithium disilicate ceramic and computer-aided design/computer-aided manufacturing (CAD/CAM) lithium disilicate ceramic in the thickness of 1.5 mm. The occlusal veneers were cemented with resin cement. The specimens were fatigued using the thermocycling and cyclic mechanical loading tests after being stored in water for 72 h. The wear of specimens was measured using gypsum replicas and 3D laser scanner before and after the thermocycling and cyclic mechanical loading tests and the mean lost distance (mm) was used to indicate the level of wear. The surfaces of occlusal contact area were observed and the surface roughness was recorded using 3D laser scanning confocal microscope before and after the fatigue test. Differences between the groups were compared using ONE-way ANOVA(Pcomposite group, heat-pressed lithium disilicate ceramic group, and CAD/CAM lithium disilicate ceramic group was (-0.13±0.03) mm, (-0.05±0.01) mm and (-0.05±0.01) mm, the wear of microhybrid composite was significantly higher than the two ceramic groups(Pcomposite was significantly higher than the two ceramic groups(Pcomposite(P=0.005) and CAD/CAM lithium disilicate ceramic (P=0.010). From the view of wear speed, microhybrid composite was significantly higher than the two kinds of ceramics, but it was similar to enamel when the opposing tooth was natural. The surface roughness before the themocycling and cyclic mechanical loading test of microhybrid

  1. EFFECT OF ARTIFICIAL WEATHERING ON WOOD LAMINATES COLOR TREATED WITH TWO FINISHING PRODUCTS

    Directory of Open Access Journals (Sweden)

    Thais Jacob Mendes

    2016-03-01

    Full Text Available Weathering is one of the main reasons for the degradation of wood, especially its color. The application of finishes minimizes these effects. This study aimed to monitor the effect of artificial weathering on wood veneer of the species cumaru (Dipteryx odorata and pau marfim (Balfourodendron riedelianum with two finishes, the marine varnish and Cetol, with monitoring using a spectrophotometer. The samples were subjected to cycles of exposure to weathering for 20, 40, 52, 76, 124, 226, 430, 838 and 960 hours. The colorimetric parameters (L*, a*, b*, C and h* were measured before treatment, after application of the products and during the weathering time intervals. The application of finishes darkened veneer of cumaru wood and pau marfim in nature. However, in higher weathering times, both species returned to a lighter color, and even became lighter than the natural wood. The use of Cetol was more efficient, giving greater stability in the conservation of wood color of the species studied.

  2. Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain.

    Science.gov (United States)

    Madani, Azamsadat; Nakhaei, Mohammadreza; Karami, Parisa; Rajabzadeh, Ghadir; Salehi, Sahar; Bagheri, Hossein

    2016-01-01

    The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and Pcoating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain.

  3. Shear bond strength of veneering porcelain to zirconia: Effect of surface treatment by CNC-milling and composite layer deposition on zirconia.

    Science.gov (United States)

    Santos, R L P; Silva, F S; Nascimento, R M; Souza, J C M; Motta, F V; Carvalho, O; Henriques, B

    2016-07-01

    The purpose of this study was to evaluate the shear bond strength of veneering feldspathic porcelain to zirconia substrates modified by CNC-milling process or by coating zirconia with a composite interlayer. Four types of zirconia-porcelain interface configurations were tested: RZ - porcelain bonded to rough zirconia substrate (n=16); PZ - porcelain bonded to zirconia substrate with surface holes (n=16); RZI - application of a composite interlayer between the veneering porcelain and the rough zirconia substrate (n=16); PZI - application of a composite interlayer between the porcelain and the zirconia substrate treated by CNC-milling (n=16). The composite interlayer was composed of zirconia particles reinforced porcelain (30%, vol%). The mechanical properties of the ceramic composite have been determined. The shear bond strength test was performed at 0.5mm/min using a universal testing machine. The interfaces of fractured and untested specimens were examined by FEG-SEM/EDS. Data was analyzed with Shapiro-Wilk test to test the assumption of normality. The one-way ANOVA followed by Tukey HSD multiple comparison test was used to compare shear bond strength results (α=0.05). The shear bond strength of PZ (100±15MPa) and RZI (96±11MPa) specimens were higher than that recorded for RZ (control group) specimens (89±15MPa), although not significantly (p>0.05). The highest shear bond strength values were recorded for PZI specimens (138±19MPa), yielding a significant improvement of 55% relative to RZ specimens (p<0.05). This study shows that it is possible to highly enhance the zirconia-porcelain bond strength - even by ~55% - by combining surface holes in zirconia frameworks and the application of a proper ceramic composite interlayer. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Evaluation of Bond Strength between Grooved Titanium Alloy Implant Abutments and Provisional Veneering Materials after Surface Treatment of the Abutments: An In vitro Study.

    Science.gov (United States)

    Venkat, Gowtham; Krishnan, Murugesan; Srinivasan, Suganya; Balasubramanian, Muthukumar

    2017-01-01

    Titanium has become the material of choice with greater applications in dental implants. The success of the dental implant does not only depend on the integration of the implant to the bone but also on the function and longevity of the superstructure. The clinical condition that demands long-term interim prosthesis is challenging owing to the decreased bond between the abutment and the veneering material. Hence, various surface treatments are done on the abutments to increase the bond strength. This study aimed to evaluate the bond strength between the abutment and the provisional veneering materials by surface treatments such as acid etching, laser etching, and sand blasting of the abutment. Forty titanium alloy abutments of 3 mm diameter and 11 mm height were grouped into four groups with ten samples. Groups A, B, C, and D are untreated abutments, sand blasted with 110 μm aluminum particles, etched with 1% hydrofluoric acid and 30% nitric acid, and laser etched with Nd: YAG laser, respectively. Provisional crowns were fabricated with bis-acrylic resin and cemented with noneugenol temporary luting cement. The shear bond strength was measured in universal testing machine using modified Shell-Nielsen shear test after the cemented samples were stored in water at 25°C for 24 h. Load was applied at a constant cross head speed of 5 mm/min until a sudden decrease in resistance indicative of bond failure was observed. The corresponding force values were recorded, and statistical analysis was done using one-way ANOVA and Newman-Keuls post hoc test. The laser-etched samples showed higher bond strength. Among the three surface treatments, laser etching showed the highest bond strength between titanium alloy implant abutment and provisional restorations. The sand-blasted surfaces demonstrated a significant difference in bond strength compared to laser-etched surfaces. The results of this study confirmed that a combination of surface treatments and bond agents enhances the

  5. Comparative Evaluation of Effects of Laser Modalities on Shear Bond Strengths of Veneering Porcelains to Laser Sintered Substructures: An In Vitro Study.

    Science.gov (United States)

    Gorler, Oguzhan; Saygin, Aysegul Goze

    2017-06-01

    Laser modalities and direct metal laser sintering (DMLS) have a potential to enhance micromechanical bonding between dental super- and infrastructures. However, the effect of different manufacturing methods on the metal-ceramic bond strength needs further evaluation. We investigated the effect of surface treatment with Er:YAG, Nd:YAG, and Ho:YAG lasers on the shear bond strength (SBS) of high-fusion dental porcelains (Vita and G-Ceram) to infrastructures prepared with DMLS in vitro settings. Study specimens (n = 128) were randomly divided into study subsets (n = 8), considering treatment types applied on the surface of infrastructures, including sandblasting and selected laser modalities; infrastructure types as direct laser sintered (DLS) and Ni-Cr based; and superstructure porcelains as Vita and G-Ceram. The SBS test was performed to assess the effectiveness of surface modifications that were also examined with a stereo microscope. Considering laser procedure types, the highest SBS values were obtained by Er:YAG laser, followed by, with a decreasing efficiency, Ho:YAG laser and sandblasting procedures, and Nd:YAG laser procedure (p laser decreases the bonding of Vita and G-Ceram in all the infrastructures compared with sandblasting. Considering porcelains, the highest SBS values were obtained by Vita (p laser procedures caused surface irregularities as revealed by the stereo microscopic examination. In current experimental settings, Er:YAG laser applied to DLS infrastructure veneered with Vita porcelain increases bonding strength more distinctly, and Nd:YAG laser applied to Ni-Cr-based infrastructure veneered with G-Ceram porcelain alters bonding strength unfavorably.

  6. Productivity

    DEFF Research Database (Denmark)

    Spring, Martin; Johnes, Geraint; Hald, Kim Sundtoft

    Productivity is increasingly critical for developed economies. It has always been important: as Paul Krugman puts it, “Productivity isn’t everything, but in the long run it is almost everything. A country’s ability to improve its standard of living over time depends almost entirely on its ability...... to raise its output per worker”(Krugman, 1994). Analyses of productivity have, by and large, been the preserve of economists. Operations Management (OM) is rooted in a similar concern for the efficient use of scarce resources; Management Accounting (MA) is concerned with the institutionalised measurement...... and management of productivity. Yet the three perspectives are rarely connected. This paper is a sketch of a literature review seeking to identify, contrast and reconcile these three perspectives. In so doing, it aims to strengthen the connections between policy and managerial analyses of productivity....

  7. Hot pressing effect on (Bi0⋅25Sb0⋅75)2Te3 mechanical and ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. (Bi0⋅25Sb0⋅75)2Te3 thermoelectric material is a well known p type of compound that has higher fig- ... The crystal of this compound was prepared, pulverized in a particle .... ing fracture surfaces of the materials as shown in figures.

  8. B2 Grain Growth Behavior of a Ti-22Al-25Nb Alloy Fabricated by Hot Pressing Sintering

    Science.gov (United States)

    Jia, Jianbo; Liu, Wenchao; Xu, Yan; Chen, Chen; Yang, Yue; Luo, Junting; Zhang, Kaifeng

    2018-05-01

    Grain growth behavior of a powder metallurgy (P/M) Ti-22Al-25Nb alloy was investigated by applying a series of isothermal treatment tests over a wide range of temperatures and holding times. An isothermal treatment scheme was conducted in the B2 phase region (1070-1110 °C) and α 2 + B2 phase region (1010-1050 °C) at holding times of 10, 30 min, 1, 2, and 3 h, respectively. The effects of temperature and holding time on the microstructure evolution and microhardness of the P/M Ti-22Al-25Nb alloy at elevated temperatures were evaluated using optical microscope, scanning electron microscope, x-ray diffraction, and Vickers hardness test techniques. The results revealed that the alloy's treated microstructure was closely linked to temperature and holding time, respectively. The change law of B2 grain growth with holding time and temperature can be well interpreted by the Beck equation and Hillert equation, respectively. The B2 grain growth exponent n and activation energy Q were acquired based on experimental data in the α 2 + B2 and B2 phase regions. In addition, the grain growth contour map for the P/M Ti-22Al-25Nb alloy was constructed to depict variations in B2 grain size based on holding time and temperature.

  9. Damage Mechanisms and Controlled Crack Propagation in a Hot Pressed Silicon Nitride Ceramic. Ph.D. Thesis - Northwestern Univ., 1993

    Science.gov (United States)

    Calomino, Anthony Martin

    1994-01-01

    The subcritical growth of cracks from pre-existing flaws in ceramics can severely affect the structural reliability of a material. The ability to directly observe subcritical crack growth and rigorously analyze its influence on fracture behavior is important for an accurate assessment of material performance. A Mode I fracture specimen and loading method has been developed which permits the observation of stable, subcritical crack extension in monolithic and toughened ceramics. The test specimen and procedure has demonstrated its ability to generate and stably propagate sharp, through-thickness cracks in brittle high modulus materials. Crack growth for an aluminum oxide ceramic was observed to be continuously stable throughout testing. Conversely, the fracture behavior of a silicon nitride ceramic exhibited crack growth as a series of subcritical extensions which are interrupted by dynamic propagation. Dynamic initiation and arrest fracture resistance measurements for the silicon nitride averaged 67 and 48 J/sq m, respectively. The dynamic initiation event was observed to be sudden and explosive. Increments of subcritical crack growth contributed to a 40 percent increase in fracture resistance before dynamic initiation. Subcritical crack growth visibly marked the fracture surface with an increase in surface roughness. Increments of subcritical crack growth loosen ceramic material near the fracture surface and the fracture debris is easily removed by a replication technique. Fracture debris is viewed as evidence that both crack bridging and subsurface microcracking may be some of the mechanisms contributing to the increase in fracture resistance. A Statistical Fracture Mechanics model specifically developed to address subcritical crack growth and fracture reliability is used together with a damaged zone of material at the crack tip to model experimental results. A Monte Carlo simulation of the actual experiments was used to establish a set of modeling input parameters. It was demonstrated that a single critical parameter does not characterize the conditions required for dynamic initiation. Experimental measurements for critical crack lengths, and the energy release rates exhibit significant scatter. The resulting output of the model produces good agreement with both the average values and scatter of experimental measurements.

  10. Nanotwinned Ti(O,C) induced by oriented attachment in a hot-pressed Nb–Ti–Al alloy

    International Nuclear Information System (INIS)

    Shi, Zhiwu; Wei, Hua; Zhang, Hongyu; Jin, Tao; Sun, Xiaofeng; Zheng, Qi

    2016-01-01

    The microstructures and formation mechanisms of various kinds of Ti(O,C) twins in a Nb–23Ti–15Al alloy have been investigated. The crystallographic features of the twins are systematically characterized using transmission electron microscopy (TEM). Lamellar or corner Ti(O,C) twins consist of coherent {111} twin boundaries (TBs) and incoherent {112} TBs. The three-fold Ti(O,C) twins are newly found, with symmetric Σ9 {114} or asymmetric Σ9 {115}/{111} serving as the secondary TBs. Moreover, slabs on Ti(O,C) TBs showing three-layer periodic contrasts are identified to be the twin overlapping. According to the microstructure characteristics, we propose a new model based on oriented attachment to interpret the formation of Ti(O,C) twins, which involves the contact, rotation, attachment and Ostwald ripening of Ti(O,C) grains. Our results provide new insights on the formation mechanisms of nanotwinned grains.

  11. 40 CFR Appendix A to Subpart Dddd... - Alternative Procedure To Determine Capture Efficiency From Enclosures Around Hot Presses in the...

    Science.gov (United States)

    2010-07-01

    ... calibration standard. 3.7Method 204. The U.S. EPA Method 204, “Criteria For and Verification of a Permanent or..., “Verification of Gas Dilution Systems for Field Instrument Calibrations” (40 CFR part 51, appendix M). 3.9Method... sulfur hexafluoride gas. Self-contained breathing apparatus may be required by rescue workers. Sulfur...

  12. Improvement of microstructure and mechanical properties of high dense SiC ceramics manufactured by high-speed hot pressing

    International Nuclear Information System (INIS)

    Voyevodin, V.; Sayenko, S.; Lobach, K.; Tarasov, R.; Zykova, A.; Svitlychnyi, Ye.; Surkov, A.; Abelentsev, V.; Ghaemi, H.; Szkodo, M.; Gajowiec, G.; Kmiec, M.; Antoszkiewicz, M.

    2017-01-01

    Non-oxide ceramics possess high physical-mechanical properties, corrosion and radiation resistance, which can be used as a protective materials for radioactive wastes disposal. The aim of the present study was the manufacturing of high density SiC ceramics with advanced physical and mechanical parameters. The high performance on the properties of produced ceramics was determined by the dense and monolithic structure. The densified silicon carbide samples possessed good mechanical strength, with a high Vickers micro hardness up to 28.5 GPa.

  13. Production of sodalite waste forms by addition of glass

    International Nuclear Information System (INIS)

    Pereira, C.

    1995-01-01

    Spent nuclear fuel can be treated in a molten salt electrorefiner for conversion into metal and mineral waste forms for geologic disposal. Sodalite is one of the mineral waste forms under study. Fission products in the molten salt are ion-exchanged into zeolite A, which is converted to sodalite and consolidated. Sodalite can be formed directly from mixtures of salt and zeolite A at temperatures above 975 K; however, nepheline is usually produced as a secondary phase. Addition of small amounts of glass frit to the mixture reduced nepheline formation significantly. Loss of fission products was not observed for reaction below 1000 K. Hot-pressing of the sodalite powders yielded dense pellets (∼2.3 g/cm 3 ) without any loss of fission product species. Normalized release rates were below 1 g/m 2 ·day for pre-washed samples in 28-day leach tests based on standard MCC-1 tests but increased with the presence of free salt on the sodalite

  14. 3D quantification of clinical marginal and internal gap of porcelain laminate veneers with minimal and without tooth preparation and 2-year clinical evaluation.

    Science.gov (United States)

    Karagözoğlu, İrem; Toksavul, Suna; Toman, Muhittin

    2016-01-01

    The aims of this clinical study were to compare internal three-dimensional (3D) adaptation of porcelain laminate veneers (PLV) with minimal tooth preparation and without tooth preparation (prepless) and to evaluate the clinical outcomes at baseline and following 6, 12, and 24 months after luting. Thirty-one prepless PLV and 31 PLV with minimal tooth preparation were fabricated using lithium disilicate glass-ceramic material and placed in 12 patients (8 women, 4 men; 18 to 40 years old). All PLV were luted with an adhesive luting system (Variolink veneer). A silicone replica was obtained to measure internal adaptation of each PLV using a low viscosity polyvinyl siloxane impression material just before luting. Silicone replicas were scanned in x-ray micro computerized tomography (micro CT). Clinical evaluations took place at baseline (2 days after luting) and following 6, 12, and 24 months after luting. Marginal integrity, marginal discoloration, secondary caries, tooth sensitivity, and fracture were evaluated following FDI criteria. Replica scores were analyzed using Mann-Whitney U and Student's t test (α = .05). Kaplan-Meier statistical analysis was done for the survival rate of PLV. FDI criteria scores were analyzed using Pearson's chi-square test (α = .05). The median marginal gaps for PLV-without-tooth-preparation and PLV-with-minimal-tooth-preparation groups were 100 μm and 140 μm respectively. There was a statistically significant difference between the two groups with respect to marginal gap (P = .04). The mean internal adaptation for the PLV-without-tooth-preparation group was 217.17 ± 54.72 μm, and was 170.67 ± 46.54 μm for the PLV-with-minimaltooth- preparation group. There was a statistically significant difference between the two groups (P = .001). Based on FDI criteria, 100% of the PLV were rated satisfactory during the 2-year period. In this in-vivo study, mean and median values of marginal gap and internal adaptation for PLV with minimal tooth

  15. Evaluation of bond strength between grooved titanium alloy implant abutments and provisional veneering materials after surface treatment of the abutments: An in vitro study

    Directory of Open Access Journals (Sweden)

    Gowtham Venkat

    2017-01-01

    Full Text Available Introduction: Titanium has become the material of choice with greater applications in dental implants. The success of the dental implant does not only depend on the integration of the implant to the bone but also on the function and longevity of the superstructure. The clinical condition that demands long-term interim prosthesis is challenging owing to the decreased bond between the abutment and the veneering material. Hence, various surface treatments are done on the abutments to increase the bond strength. Aim: This study aimed to evaluate the bond strength between the abutment and the provisional veneering materials by surface treatments such as acid etching, laser etching, and sand blasting of the abutment. Materials and Methods: Forty titanium alloy abutments of 3 mm diameter and 11 mm height were grouped into four groups with ten samples. Groups A, B, C, and D are untreated abutments, sand blasted with 110 μm aluminum particles, etched with 1% hydrofluoric acid and 30% nitric acid, and laser etched with Nd: YAG laser, respectively. Provisional crowns were fabricated with bis-acrylic resin and cemented with noneugenol temporary luting cement. The shear bond strength was measured in universal testing machine using modified Shell–Nielsen shear test after the cemented samples were stored in water at 25°C for 24 h. Load was applied at a constant cross head speed of 5 mm/min until a sudden decrease in resistance indicative of bond failure was observed. The corresponding force values were recorded, and statistical analysis was done using one-way ANOVA and Newman–Keuls post hoc test. Results: The laser-etched samples showed higher bond strength. Conclusion: Among the three surface treatments, laser etching showed the highest bond strength between titanium alloy implant abutment and provisional restorations. The sand-blasted surfaces demonstrated a significant difference in bond strength compared to laser-etched surfaces. The results of this

  16. In Vitro Comparison of Marginal and Internal Fit of Press-on-Metal Ceramic (PoM) Restorations with Zirconium-Supported and Conventional Metal Ceramic Fixed Partial Dentures Before and After Veneering.

    Science.gov (United States)

    Varol, Seda; Kulak-Özkan, Yasemin

    2015-07-01

    To compare marginal and internal fit between 3- and 4-unit press-on-metal (PoM) ceramic, zirconia-supported, and conventional metal ceramic fixed partial dentures (FPDs) before and after veneering. Ten pieces for each 3- and 4-unit MC, IPS InLine PoM, and IPS e.max ZirCAD/Zir Press FPDs were produced. Cross-sections from silicone replicas were examined and measured with a light microscope. Occlusal, axial, intermarginal, and marginal mean adaptation scores of cross-sectioned replicas and means of measurements obtained from 4 sites were calculated independently. Mean values for molars were 78.44 ± 32.01 μm (MC), 89.84 ± 29.20 μm (PoM), and 85.17 ± 28.49 μm (Zir). Premolar values were 76.08 ± 27.92 μm (MC), 89.94 ± 23.49 μm (PoM), and 87.18 ± 28.25 μm (Zir). No difference existed between the means of 3- and 4-unit FPDs except the molar-intermarginal region. The mean value of 4-unit FPDs (93.88 ± 25.41 μm) was less than the 3-unit FPDs (103.68 ± 24.55 μm) at the molar-inter marginal region. A gap increase was observed in all sites except the molar-axio-occlusal region after veneering. According to the mean difference, gap increases at the molar-marginal, molar-intermarginal, and premolar-intermarginal regions were statistically significant. A statistical difference was found at the molar-marginal region for 4-unit MCR (p = 0.041) and 4-unit PoM FPDs (p = 0.042) before and after veneering. Gap increase after veneering of 4-unit metal ceramics at molar-intermarginal, premolar-marginal, and premolar-intermarginal regions (p = 0.020; p = 0.015; p = 0.004) was significant. The gap measurements of the IPS InLine PoM and IPS e.max ZirCAD/Zir Press groups were all clinically acceptable. No studies on marginal and internal fit in the IPS InLine PoM system have been published to date. This study should be supported with future studies. No significant increase was observed after press-veneering the IPS e.max ZirCAD frameworks with an IPS e.max ZirPress material

  17. Preparation and testing of plant seed meal-based wood adhesives.

    Science.gov (United States)

    He, Zhongqi; Chapital, Dorselyn C

    2015-03-05

    Recently, the interest in plant seed meal-based products as wood adhesives has steadily increased, as these plant raw materials are considered renewable and environment-friendly. These natural products may serve as alternatives to petroleum-based adhesives to ease environmental and sustainability concerns. This work demonstrates the preparation and testing of the plant seed-based wood adhesives using cottonseed and soy meal as raw materials. In addition to untreated meals, water washed meals and protein isolates are prepared and tested. Adhesive slurries are prepared by mixing a freeze-dried meal product with deionized water (3:25 w/w) for 2 hr. Each adhesive preparation is applied to one end of 2 wood veneer strips using a brush. The tacky adhesive coated areas of the wood veneer strips are lapped and glued by hot-pressing. Adhesive strength is reported as the shear strength of the bonded wood specimen at break. Water resistance of the adhesives is measured by the change in shear strength of the bonded wood specimens at break after water soaking. This protocol allows one to assess plant seed-based agricultural products as suitable candidates for substitution of synthetic-based wood adhesives. Adjustments to the adhesive formulation with or without additives and bonding conditions could optimize their adhesive properties for various practical applications.

  18. Research physic-mechanical properties of composite materials on the base of peeled veneer and low density polyethylene

    Science.gov (United States)

    Ibragimov, Aleksandr; Vasilkin, Andrey; Fedotov, Aleksandr

    2017-10-01

    Use film of LDPE as thermoplastic binder for production of plywood is proposed. Results of physic-mechanical properties of plywood based on the LDPE film of different thicknesses in comparison with conventional thermosetting synthetic binder are presented.

  19. Method for production of transparent yttrium oxide

    International Nuclear Information System (INIS)

    Dutta, S.K.; Gazza, G.A.

    1975-01-01

    The method comprises vacuum hot pressing the yttrium oxide (Y 2 O 3 ) powder in a graphite die at temperatures of between 1300 to 1500 0 C and uniaxial pressures of between 5000 to 7000 psi, for a period of 1 to 2 hours. (U.S.)

  20. Application of tung oil to improve adhesion strength and water resistance of cottonseed meal and protein adhesives on maple veneer

    Science.gov (United States)

    Cottonseed meal-based products show promise in serving as environment-friendly wood adhesives. However, their practical utilization is currently limited due to low durability and water resistant properties. In this research, we tested the improvement of adhesion strength and water resistance of cott...

  1. The effect of different surface treatments of stainless steel crown and different bonding agents on shear bond strength of direct composite resin veneer

    Directory of Open Access Journals (Sweden)

    Ajami B

    2007-01-01

    Full Text Available Background and Aim: Stainless steel crown (SSC is the most durable and reliable restoration for primary teeth with extensive caries but its metalic appearance has always been a matter of concern. With advances in restorative materials and metal bonding processes, composite veneer has enhanced esthetics of these crowns in clinic. The aim of this study was to evaluate the shear bond strength of SSC to composite resin using different surface treatments and adhesives. Materials and Methods: In this experimental study, 90 stainless steel crowns were selected. They were mounted in molds and divided into 3 groups of 30 each (S, E and F. In group S (sandblast, buccal surfaces were sandblasted for 5 seconds. In group E (etch acidic gel was applied for 5 minutes and in group F (fissure bur surface roughness was created by fissure diamond bur. Each group was divided into 3 subgroups (SB, AB, P based on different adhesives: Single Bond, All Bond2 and Panavia F. Composite was then bonded to specimens. Cases were incubated in 100% humidity at 37°C for 24 hours. Shear bond strength was measured by Zwick machine with crosshead speed of 0.5 mm/min. Data were analyzed by ANOVA test with p0.05 so the two variables were studied separately. No significant difference was observed in mean shear bond strength of composite among the three kinds of adhesives (P>0.05. Similar results were obtained regarding surface treatments (P>0.05. Conclusion: Based on the results of this study, treating the SSC surface with bur and using single bond adhesive and composite can be used successfully to obtain esthetic results in pediatric restorative treatments.

  2. Ceramic (Feldspathic & IPS Empress II) vs. laboratory composite (Gradia) veneers; a comparison between their shear bond strength to enamel; an in vitro study.

    Science.gov (United States)

    Nikzad, S; Azari, Abbas; Dehgan, S

    2010-07-01

    Patient demand for aesthetic dentistry is steadily growing. Laminates and free metal restorations have evolved in an attempt to overcome the invasiveness nature of full veneer restorations. Although many different materials have been used for making these restorations, there is no single material that fits best for all purposes. Two groups of ceramic material (Feldspathic and IPS Empress II) and one group of laboratory composite (Gradia) discs (10 discs in each group; 4 mm in diameter and 2 mm in thickness) were prepared according to the manufacturer's instruction. The surface of ceramic discs were etched and silanized. In Gradia group, liquid primer was applied on composite surfaces. Thirty freshly extracted sound human molars and premolars were randomly divided into three groups. The enamel surface of each tooth was slightly flattened (0.3 mm) on the buccal or lingual side and then primed and cemented to the prepared discs with the aid of a dental surveyor. The finishing specimens were thermocycled between 5 degrees C and 55 degrees C for 2500 cycles and then prepared for shear bond strength testing. The resulting data were analyzed by one-way anova and Tukey HSD test. The fractured surfaces of each specimen were inspected by means of stereomicroscope and SEM. There is significant difference between the bond strength of materials tested. The mean bond strengths obtained with Feldspathic ceramic, IPS Empress II and Gradia were 33.10 +/- 4.31 MPa, 26.04 +/- 7.61 MPa and 14.42 +/- 5.82 MPa, respectively. The fracture pattern was mainly mixed for ceramic groups. More scientific evidence needed for standardization of bonding protocols.

  3. Effects of core-to-dentin thickness ratio on the biaxial flexural strength, reliability, and fracture mode of bilayered materials of zirconia core (Y-TZP) and veneer indirect composite resins.

    Science.gov (United States)

    Su, Naichuan; Liao, Yunmao; Zhang, Hai; Yue, Li; Lu, Xiaowen; Shen, Jiefei; Wang, Hang

    2017-01-01

    Indirect composite resins (ICR) are promising alternatives as veneering materials for zirconia frameworks. The effects of core-to-dentin thickness ratio (C/Dtr) on the mechanical property of bilayered veneer ICR/yttria-tetragonal zirconia polycrystalline (Y-TZP) core disks have not been previously studied. The purpose of this in vitro study was to assess the effects of C/Dtr on the biaxial flexural strength, reliability, and fracture mode of bilayered veneer ICR/ Y-TZP core disks. A total of 180 bilayered 0.6-mm-thick composite resin disks in core material and C/Dtr of 2:1, 1:1, and 1:2 were tested with either core material placed up or placed down for piston-on-3-ball biaxial flexural strength. The mean biaxial flexural strength, Weibull modulus, and fracture mode were measured to evaluate the variation trend of the biaxial flexural strength, reliability, and fracture mode of the bilayered disks with various C/Dtr. One-way analysis of variance (ANOVA) and chi-square tests were used to evaluate the variation tendency of fracture mode with the C/Dtr or material placed down during testing (α=.05). Light microscopy was used to identify the fracture mode. The mean biaxial flexural strength and reliability improved with the increase in C/Dtr when specimens were tested with the core material either up and down, and depended on the materials that were placed down during testing. The rates of delamination, Hertzian cone cracks, subcritical radial cracks, and number of fracture fragments partially depended on the C/Dtr and the materials that were placed down during testing. The biaxial flexural strength, reliability, and fracture mode in bilayered structures of Y-TZP core and veneer ICR depend on both the C/Dtr and the material that was placed down during testing. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Clinical Performance of One-Piece, Screw-Retained Implant Crowns Based on Hand-Veneered CAD/CAM Zirconia Abutments After a Mean Follow-up Period of 2.3 Years.

    Science.gov (United States)

    Schnider, Nicole; Forrer, Fiona Alena; Brägger, Urs; Hicklin, Stefan Paul

    The aim of this study was to evaluate the clinical performance of one-piece, screw-retained implant crowns based on hand-veneered computer-aided design/computer-aided manufacture (CAD/CAM) zirconium dioxide abutments with a crossfit connection at least 1 year after insertion of the crown. Consecutive patients who had received at least one Straumann bone level implant and one-piece, screw-retained implant crowns fabricated with CARES zirconium dioxide abutments were reexamined. Patient satisfaction, occlusal and peri-implant parameters, mechanical and biologic complications, radiologic parameters, and esthetics were recorded. A total of 50 implant crowns in the anterior and premolar region were examined in 41 patients. The follow-up period of the definitive reconstructions ranged from 1.1 to 3.8 years. No technical and no biologic complications had occurred. At the reexamination, 100% of the implants and reconstructions were in situ. Radiographic evaluation revealed a mean distance from the implant shoulder to the first visible bone-to-implant contact of 0.06 mm at the follow-up examination. Screw-retained crowns based on veneered CAD/CAM zirconium dioxide abutments with a crossfit connection seem to be a promising way to replace missing teeth in the anterior and premolar region. In the short term, neither failures of components nor complications were noted, and the clinical and radiographic data revealed stable hard and soft tissue conditions.

  5. Overview and forecast on forestry productions worldwide.

    Science.gov (United States)

    Wenjun, Zhang

    2007-02-01

    Our world is largely dependent upon the forestry productions. Through the exploitation of forest reserves, we manufacture various industrial products, furniture, and obtain fuel and energy. Forestry productions should be conducted without large-scale deforestation and environmental degradation. In present study we perform a review and forecast analysis on forestry productions worldwide, with the objectives of providing an insight into the trend for several types of forestry productions in the future, and providing referential data for sustainable forestry productions and environmental management. Polynomial functions are used to fit trajectories of forestry productions since 1961 and forecasts during the coming 20 years are given in detail. If the past pattern continues, world fibreboard production would dramatically grow and reach 224,300,000 +/- 44,400,000 m(3) by the year 2020, an increase up to 240.7 to 408.9% as compared to the present level. Roundwood production of the world would change by -55.5 to 70.4% and reach 3,526,600,000 +/- 2,066,800,000 m(3) by 2020. In 2020 world production of sawlogs and veneer logs would change by -100 to 164.6% and reach 1,212,900,000 +/- 1,242,600,000 m(3). Global wood fuel production would change by -68.9 to 1.4% and reach 1,130,900,000 +/- 600,800,000 m(3) by 2020. Forestry productions in developed countries would largely surpass productions in developing countries in the near future. World forestry production grew since 1961 excluding wood fuel. Roundwood and wood fuel account for the critical proportions in the forestry productions. Wood fuel production has being declined and rapid growing of roundwood production has slowed in recent years. Widespread use of regenerative wood substitutes and worldwide afforestation against deforestation will be among the most effective ways to reduce deforestation and environment degradation associated with forestry productions.

  6. Beryllium—A critical mineral commodity—Resources, production, and supply chain

    Science.gov (United States)

    Lederer, Graham W.; Foley, Nora K.; Jaskula, Brian W.; Ayuso, Robert A.

    2016-11-14

    Beryllium is a lightweight metallic element used in a wide variety of specialty and industrial applications. As a function of its unique chemical and physical properties, such as a high stiffness-to-weight ratio, resistance to temperature extremes, and high thermal conductivity, beryllium cannot be easily replaced by substitute materials in applications where combinations of these properties make it the material of choice. Because the number of beryllium producers is limited and the use of substitute materials in specific defense-related applications that are vital to national security is inadequate, several studies have categorized beryllium as a critical and strategic material. This categorization has led to the United States Government recommending that beryllium be stockpiled for use in the event of a national emergency. As of December 31, 2015, the National Defense Stockpile inventory of hot-pressed beryllium metal powder, structured beryllium metal powder, and vacuum-cast beryllium metal totaled 78 metric tons (t).The U.S. Geological Survey (USGS) Mineral Resources Program supports research on the occurrence, quality, quantity, and availability of mineral resources vital to the economy and national security. The USGS, through its National Minerals Information Center (NMIC), collects, analyzes, and disseminates information on more than 90 nonfuel mineral commodities from more than 180 countries. This fact sheet provides information on the production, consumption, supply chain, geology, and resource availability of beryllium in a global context.

  7. Demonstration of production of tungsten metal powder and its consolidation into shapes

    International Nuclear Information System (INIS)

    Majumdar, S.; Kishor, J.; Paul, B.; Kain, V.; Dey, G.K.

    2016-01-01

    Tungsten is a strategically important metal used as plasma facing component in fusion reactors, radiation shields in cancer therapy machines, ammunition in defence applications, high speed cutting tools etc. The primary resources or minerals occurring in India contain a very low value (0.25-0.5 wt. %) of tungsten. Mineral beneficiation processes involving crushing, grinding, primary and secondary gravity separation, floatation are essential to produce the ore-concentrate suitable for further processing up to the preparation of the intermediate ammonium para-tungstate (APT). APT was further converted to tungsten tri-oxide (WO_3). Hydrogen reduction of WO_3 producing high purity W metal powder was demonstrated in large scale batches. Densification of W powder was further studied using vacuum hot pressing at 1950°C, and high density W metal plates of 5 mm thickness and 60 mm diameter were produced. The products obtained at every stage were systematically characterized using X-Ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and electron backscattered diffraction (EBSD) techniques. (author)

  8. Effect of cooling rate on tetragonal to monoclinic transformation in hot pressed ZrO2(Y2O3) ceramics

    International Nuclear Information System (INIS)

    Zhu, W.Z.; Ding, Z.S.; Lei, T.C.; Zhou, Y.

    1995-01-01

    It is well documented that the tetragonal (T) to monoclinic (M) transition in either pure zirconia or partially stabilized zirconia is the origin of toughening in that resistance to the propagation of cracks can be greatly enhanced by the concurrent appearance of the stress field of the transformation. In the present paper, the effect of cooling rate on the T → M phase transformation in yttria-containing zirconia and its resultant mechanical properties have been studied by means of thermal expansion analysis. Both the T → M and M → T transformations are affected by the cooling and heating rates, respectively. The amount of M-phase decreases with increasing cooling rate. T → M transition occurring within the interior part of specimen can be completely inhibited by the cooling rate of 100 C/min for ZrO 2 (2mol% Y 2 O 3 ) ceramic sintered at 1,600 C. The start point and end point of the T → M transformation decreases and increases, respectively, with increasing cooling rate. Both the start point and end point of the M → T transformation increase with increasing cooling rate. The divergence between the results of X-ray diffraction and the thermal expansion analysis has been rationalized in terms of the both internal and external factors, namely, preferential sites of surface for the formation of the M-phase and limited sensitivity of measurement of the thermal expansion apparatus. Both the water-cooled and air-cooled specimens show much improved mechanical properties regardless of the sintering temperatures or yttria content because of the relatively higher T-phase fraction retained to room temperature

  9. International Clean Energy System Using Hydrogen Conversion (WE-NET). subtask 4. Development of hydrogen production technology; Suiso riyo kokusai clean energy system gijutsu (WE-NET). subtask 4. Suiso seizo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    This paper describes development of hydrogen production technology as a part of the WE-NET project. For the solid polymer water electrolysis method higher in efficiency and lower in cost than the previous methods, 5 companies have developed element technologies for improving electrolysis cells and synthesis technologies of hot solid polymer electrolyte based on each proper catalyst electrode production method. In fiscal 1996, the initial study on large-scale systems by middle laboratory cells was made as well as improvement of electrolysis performance by small laboratory cells and endurance tests. Among the previous methods such as a hot press method (bonding of an ion exchange membrane to an electrode), an electroless plating method (preparation of porous surface onto a membrane electrode assembly), a zero gap method (preparation of high-efficiency high-current density cells), and a sintered porous electrode method (carrying of the mixture of catalytic powder and ion exchange resin-dissipated solution onto sintered metallic porous electrode surface), the former two methods were adopted for development of bench-scale cells as effective promising methods. 192 refs., 183 figs., 108 tabs.

  10. Fiscal 1997 survey report. Subtask 4 (hydrogen utilization worldwide clean energy system technology) (WE-NET) (development of hydrogen production technology); 1997 nendo seika hokokusho. Suiso riyo kokusai clean energy system gijutsu (WE-NET) subtask 4 suiso seizo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    As a WE-NET subtask, a study has been conducted of the solid polyelectrolyte water electrolysis method by which higher efficiency and lower cost hydrogen production is expected than in the conventional hydrogen production method. Production methods of electrode, electrolyte, etc. were studied. In the electroless plating method, the manufacturing process of membrane-electrode assemblies was realized in a large area of 2500 cm{sup 2} by the porous-surfaced method by studying manufacturing conditions for slurry membrane/membrane assembly/electroless plating processes. In the hot-press method, the refining degree and dispersibility of iridium dioxide powder were studied to improve characteristics of anode catalyst. A method was developed to form polyelectrolyte coatings homogeneously on the surface of electrode layer catalytic powder, and a large area of 2500 cm{sup 2} was realized. Beside the performance test using large single cells, FS was conducted to discuss optimum operating conditions and optimum structures of plants. Both methods indicated the performance exceeding the energy conversion efficiency of 90%, a WE-NET target, at current density of 1A/cm{sup 2} and electrolysis temperature of 80degC. A key was found to a bench-scale development (electrode area of 2500 cm{sup 2}, about 5 layers) to be planned in fiscal 1998. 136 figs., 50 tabs.

  11. Ceramic Hosts for Fission Products Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Peter C Kong

    2010-07-01

    Natural spinel, perovskite and zirconolite rank among the most leach resistant of mineral forms. They also have a strong affinity for a large number of other elements and including actinides. Specimens of natural perovskite and zirconolite were radioisotope dated and found to have survived at least 2 billion years of natural process while still remain their loading of uranium and thorium . Developers of the Synroc waste form recognized and exploited the capability of these minerals to securely immobilize TRU elements in high-level waste . However, the Synroc process requires a relatively uniform input and hot pressing equipment to produce the waste form. It is desirable to develop alternative approaches to fabricate these durable waste forms to immobilize the radioactive elements. One approach is using a high temperature process to synthesize these mineral host phases to incorporate the fission products in their crystalline structures. These mineral assemblages with immobilized fission products are then isolated in a durable high temperature glass for periods measured on a geologic time scale. This is a long term research concept and will begin with the laboratory synthesis of the pure spinel (MgAl2O4), perovskite (CaTiO3) and zirconolite (CaZrTi2O7) from their constituent oxides. High temperature furnace and/or thermal plasma will be used for the synthesis of these ceramic host phases. Nonradioactive strontium oxide will be doped into these ceramic phases to investigate the development of substitutional phases such as Mg1-xSrxAl2O4, Ca1-xSrxTiO3 and Ca1-xSrxZrTi2O7. X-ray diffraction will be used to establish the crystalline structures of the pure ceramic hosts and the substitution phases. Scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX) will be performed for product morphology and fission product surrogates distribution in the crystalline hosts. The range of strontium doping is planned to reach the full substitution of the divalent

  12. Cesium release from ceramic waste form materials in simulated canister corrosion product containing solutions

    Energy Technology Data Exchange (ETDEWEB)

    Vittorio, Luca; Drabarek, Elizabeth; Chronis, Harriet; Griffith, Christopher S

    2004-07-01

    It has previously been demonstrated that immobilization of Cs{sup +} and/or Sr{sup 2+} sorbed on hexagonal tungsten oxide bronze (HTB) adsorbent materials can be achieved by heating the materials in air at temperatures in the range 500 - 1300 deg C. Highly crystalline powdered HTB materials formed by heating at 800 deg C show leach characteristics comparable to Cs-containing hot-pressed hollandites in the pH range from 0 to 12. As a very harsh leaching test, and also to model in a basic manner, leaching in the presence of canister corrosion products in oxidising environments, leaching of the bronzoid phases has been undertaken in Fe(NO{sub 3}){sub 3} solutions of increasing concentration. This is done in comparison with Cs -hollandite materials in order to compare the leaching characteristics of these two materials under such conditions. Both the Cs-loaded bronze and hollandite materials leach severely in Fe(NO{sub 3}){sub 3} losing virtually all of the immobilized Cs in a period of four days at 150 deg C. Total release of Cs and conversion of hollandite to titanium and iron titanium oxides begins to be observed at relatively low concentrations and is virtually complete after four days reaction in 0.5 mol/L Fe(NO{sub 3}){sub 3}. In the case of the bronze, all of the Cs is also extracted but the HTB structure is preserved. The reaction presumably involves an ion-exchange mechanism and iron oxide with a spinel structure is also observed at high Fe concentrations. (authors)

  13. Cesium release from ceramic waste form materials in simulated canister corrosion product containing solutions

    International Nuclear Information System (INIS)

    Vittorio, Luca; Drabarek, Elizabeth; Chronis, Harriet; Griffith, Christopher S.

    2004-01-01

    It has previously been demonstrated that immobilization of Cs + and/or Sr 2+ sorbed on hexagonal tungsten oxide bronze (HTB) adsorbent materials can be achieved by heating the materials in air at temperatures in the range 500 - 1300 deg C. Highly crystalline powdered HTB materials formed by heating at 800 deg C show leach characteristics comparable to Cs-containing hot-pressed hollandites in the pH range from 0 to 12. As a very harsh leaching test, and also to model in a basic manner, leaching in the presence of canister corrosion products in oxidising environments, leaching of the bronzoid phases has been undertaken in Fe(NO 3 ) 3 solutions of increasing concentration. This is done in comparison with Cs -hollandite materials in order to compare the leaching characteristics of these two materials under such conditions. Both the Cs-loaded bronze and hollandite materials leach severely in Fe(NO 3 ) 3 losing virtually all of the immobilized Cs in a period of four days at 150 deg C. Total release of Cs and conversion of hollandite to titanium and iron titanium oxides begins to be observed at relatively low concentrations and is virtually complete after four days reaction in 0.5 mol/L Fe(NO 3 ) 3 . In the case of the bronze, all of the Cs is also extracted but the HTB structure is preserved. The reaction presumably involves an ion-exchange mechanism and iron oxide with a spinel structure is also observed at high Fe concentrations. (authors)

  14. Fiscal 1999 hydrogen utilization international clean energy system technology (WE-NET). Phase 2 R and D (Task 8) - development of hydrogen production technology; 1999 nendo suiso riyo kokusai clean energy system gijutsu (WE-NET) dainiki kenkyu kaihatsu. Task 8. Suiso seizo gijutsu no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    R and D was conducted with the view of establishing hydrogen production technology based on the solid high polymer electrolyte water electrolysis method, which presumably offers higher efficiency and lower cost than conventional methods. This year, as well as implementing development of large-scale cell lamination (electrode area 2,500 cm{sup 2}, 10 cells) by using two hydrogen production methods (electroless plating method and hot press method), work was started for developing cells (electrode area 1,000 cm{sup 2}) for hydrogen stations. In the research on longterm durability improvement, with a 50 cm{sup 2} membrane electrolyte or cell, the evaluation test results were obtained of stable electrolytic performance showing more than 93% energy efficiency after 400 hour operation, under the conditions with electrolysis pressure 0.4MPa and electrolysis temperature 120 degree C. In a test of 1,000 cm{sup 2} prototype cell for hydrogen stations, the evaluation result was obtained for energy efficiency of 92% under the conditions with electrolysis pressure 0.5MPa and electrolysis temperature 120 degree C; thus, this year's target efficiency of over 90% was achieved. Further, enhancement of the quality was contrived for example by improving the electroless plating method and remodeling a roll press machine. (NEDO)

  15. Qualidade de juntas coladas com lâminas de madeira oriundas de três regiões do tronco de Eucalyptus grandis, Eucalyptus saligna e Pinus elliottii Quality of wood joints glued with wood veneers from three trunk regions of Eucalyptus grandis, Eucalyptus saligna and Pinus elliottii

    Directory of Open Access Journals (Sweden)

    Benedito Rocha Vital

    2006-08-01

    Full Text Available Este experimento teve como objetivo avaliar a resistência de juntas coladas formadas pelas combinações de lâminas provenientes de três posições no tronco da madeira de Eucalyptus grandis, Eucalyptus saligna e Pinus elliottii. Foram empregados adesivos à base de poliacetato de vinila de média e alta viscosidade e resorcinol-formaldeído nas gramaturas de 150 g/m², em face simples para o poliacetato de vinila de média e alta viscosidades e 300 g/m², em face dupla, para o adesivo resorcinólico. O teor médio de umidade das lâminas, no momento da colagem, foi igual a 14%. Os valores médios mais elevados de resistência ao cisalhamento foram obtidos nas juntas produzidas com madeira de Eucalyptus saligna, coladas com adesivos de poliacetato de média viscosidade e resorcinol-formaldeído. A maior porcentagem de falha profunda na madeira foi obtida em juntas de madeira de Pinus elliottii, unidas com adesivo de poliacetato de alta viscosidade, seguidas das juntas de Eucalyptus grandis e coladas com adesivo de poliacetato de média viscosidade. As combinações de lâminas oriundas das seguintes posições no tronco: medula e casca, intermediária e casca e casca e casca resultaram em linhas de cola com maiores resistências ao cisalhamento.The objective of this work was to evaluate the shear strength of glued wood joints from pith, outer and intermediary wood of Eucalyptus saligna, Eucalyptus grandis and Pinus elliottii. High and medium viscosity polyvinyl acetate and resorcinol-phenol adhesives were applied at spread rate of 150 g/m² in single line and at spread rate of 300 g/m² in double glue line for the resorcinolic adhesive. The mean wood moisture content was 14%. Higher shear strength was obtained with Eucalyptus saligna veneer glued with medium viscosity polyvinyl resorcinolic adhesive. The highest percentage of wood failure was found on Pinus elliottii veneer glued with high viscosity polyvinyl acetate adhesive followed by

  16. CIRI FINIR KUPAS KAYU JABON (ANTHOCEPHALUS CADAMBA

    Directory of Open Access Journals (Sweden)

    Abigael Kabe

    2013-12-01

    Full Text Available Fast growing jabon is largely rotary-cut to produce veneer for plywood, com-ply, and LVL. In order to provide better information on veneer production and utilization, in this study the effects of wood juvenility and veneer thickness on lathe checks of jabon rotary-cut veneer were evaluated. Before veneer manufacturing, the jabon log was boiled at 50 and 75 °C for 4 and 8 hours respectively. The boiled logs were peeled to produce veneer of 1 and 2 mm thick. Lathe checks of veneers were measured under an optical video microscope. The rotary-cut veneer was grouped and evaluated separately at every segmented ring of 1 cm from pith to bark. The results showed that wood juvenility and veneer thickness had an important effect on lathe checks for the rotary-cut veneer. In general, the number of lathe check of the veneer increases with increasing veneer thickness and increase from pith to bark. Boiling of logs before rotary-cutting could decrease the value of lathe check. The results indicated that boiling of logs at 50 °C for 8 hours, and at 75 °C for 4 and 8 hours could minimize the number of lathe checks in manufacturing of 1 and 2 mm rotary-cut veneer from juvenile wood jabon.

  17. A new approach to defining rotation ages on the basis of productive and technological aspects. Application to natural Pinus sylvestris L. stands in Central Spain

    International Nuclear Information System (INIS)

    Rojo-Alboreca, A.; García-Villabrille, J.D.; Corral-Rivas, J.J.; Alía, R.; Montero, G.

    2017-01-01

    Aim of study: To propose a new approach to defining rotation ages on the basis of productive and technological aspects and to present an example of application of the methodology to natural Pinus sylvestris stands in relation to silvicultural treatment (light or heavy thinning) and site index. Area of study: Central Spain. Material and methods: We assumed that the price per m3 of logwood suitable for veneer is four times higher than logwood not apt for veneer. Considering the yield distribution for different technological and commercial classes, a model of diameter distributions and yield tables, the variation in an average price index for different age classes, site indexes and silvicultural treatments was calculated. The age at which the price index rises by less than 3%, the proportion of trees with d.b.h. higher than 40 cm, and other aspects such as the possible presence of fungal decay in old-growth stands were also taken into account to establish three criteria for defining rotation ages. Main results: The proposed methodology generates a wide range of rotation ages between 100 and 140 years for lightly thinned stands, and between 90 and 140 years for heavily thinned stands, depending on the site index. Research highlights: The proposed approach is based on technological and productive criteria, with the limitations imposed by sanitary risks. The methodology can be applied to generate rotation ages in relation to different site indexes and silvicultural treatments, provided that the timber market prices and the yield distribution for different technological and commercial classes are known, and that a model of diameter distributions and yield tables are available.

  18. A new approach to defining rotation ages on the basis of productive and technological aspects. Application to natural Pinus sylvestris L. stands in Central Spain

    Energy Technology Data Exchange (ETDEWEB)

    Rojo-Alboreca, A.; García-Villabrille, J.D.; Corral-Rivas, J.J.; Alía, R.; Montero, G.

    2017-11-01

    Aim of study: To propose a new approach to defining rotation ages on the basis of productive and technological aspects and to present an example of application of the methodology to natural Pinus sylvestris stands in relation to silvicultural treatment (light or heavy thinning) and site index. Area of study: Central Spain. Material and methods: We assumed that the price per m3 of logwood suitable for veneer is four times higher than logwood not apt for veneer. Considering the yield distribution for different technological and commercial classes, a model of diameter distributions and yield tables, the variation in an average price index for different age classes, site indexes and silvicultural treatments was calculated. The age at which the price index rises by less than 3%, the proportion of trees with d.b.h. higher than 40 cm, and other aspects such as the possible presence of fungal decay in old-growth stands were also taken into account to establish three criteria for defining rotation ages. Main results: The proposed methodology generates a wide range of rotation ages between 100 and 140 years for lightly thinned stands, and between 90 and 140 years for heavily thinned stands, depending on the site index. Research highlights: The proposed approach is based on technological and productive criteria, with the limitations imposed by sanitary risks. The methodology can be applied to generate rotation ages in relation to different site indexes and silvicultural treatments, provided that the timber market prices and the yield distribution for different technological and commercial classes are known, and that a model of diameter distributions and yield tables are available.

  19. The Formation Mechanism of Cu(In0.7Ga0.3Se2 Nanoparticles and the Densification Trajectory of the Se-Rich Quaternary Target by Hot Pressing

    Directory of Open Access Journals (Sweden)

    Qiang Ma

    2018-03-01

    Full Text Available In this paper, a method to obtain the CuInGaSe2 (CIGS absorber layer with an appropriate selenium content is put forward, in which a Se-rich target is used to deposit a CIGS thin-film and this film is annealed in a Se-free inert atmosphere. The key issue of this method is the preparation of a Se-rich target with a homogeneous composition and a high-density. The formation mechanism of CuInSe2 and CuGaSe2 is investigated and the results point to the intermediate phase Cu2−xSe playing a role of a nucleation core. The sintering densification trajectory of the target with the addition of extra selenium is researched. Additionally, an effective way to avoid the sintering defects is proposed. Finally, a conversion efficiency of 11.2% for the CIGS solar cell is reached by sputtering from the obtained Se-rich target.

  20. Value-added products from chicken feather fiber and protein

    Science.gov (United States)

    Fan, Xiuling

    Worldwide poultry consumption has generated a huge amount of feather "waste" annually. Currently, the feather has a low value-being used for animal feed in the world. The quality of fibrous air filters depend on their main component, fibers. The main physical structure of chicken feathers is barbs which can be used directly as fibers. They have small diameter, which makes them a good choice for air filtration. The main chemical structure of chicken feathers is structural fibrous protein, keratin. Therefore, chicken feathers could potentially be used for protein fiber production. To obtain chicken feather fibers, barbs were stripped from the quills by a stripping device and separated with a blender. Some feather fibers were entangled with polyester staple fibers, and needlepunched to form a nonwoven fabric. Some feather fibers were blended with CelBond(TM) bi-component polyester as binder fibers, and pressed between two hot plates to produce thermobonded nonwovens. Whole chicken feathers were ground into powder and their keratin was reduced in water. The reduced keratin was salt precipitated, dried and dissolved in ionic liquid with/without bleach cotton. The reduced chicken feather keratin ionic liquid solutions were spun into regenerated fibers through dry-jet wet spinning. The needlepunched and thermobonded nonwovens were tested for filtration and other properties. With an increase of areal density and feather fiber composition, the air permeability of the needlepunched nonwovens decreased, and their filtration efficiency and pressure drop both increased. The case can be made that feather fibers gave fabrics better filtration at the same fabric weight, but at the expense of air permeability and pressure drop. The scrim and needlepunching process improved the filtration efficiency. Their strength depended on scrim. The hot-press process was very simple. The thermobonded nonwovens had very high air permeability. In them, there was also an inverse relation between

  1. Determining stocks and flows of structural wood products in single family homes in the United States between 1950 and 2010

    DEFF Research Database (Denmark)

    Sianchuk, Robert A.; McFarlane, Paul N.; Ackom, Emmanuel

    2012-01-01

    The stocks and flows of six major structural wood products (SWPs)-lumber, plywood, oriented strand board [OSB], glue laminated timber, I-joists, and laminated veneer lumber (LVL)-in US single family homes were modeled from 1950 to 2010. The consumption of these products in US single family homes...... and their emissions as construction and demolition wastes were estimated. The net consumption of SWPs decreased from 119 kg/m2 constructed in 1986 to 82 kg/m2 in 2010. Softwood lumber was consistently the predominant SWP, but its usage intensity decreased from 95 kg/m2 in 1986 to 52 kg/ m2 in 2010. Since the 1980s......, modern SWPs, such as I-joists, LVL, and OSB, have replaced lumber and plywood products. The needs of the US single family housing industry have been met by a smaller mass of SWPs per unit area constructed. The mass of SWP present in construction wastes was influenced strongly by building cycles...

  2. GRASP - A Prototype Interactive Graphic Sawing Program - (Forest Products Journal)

    Science.gov (United States)

    Luis G. Occeña; Daniel L. Schmoldt

    1996-01-01

    A versatile microcomputer-based interactive graphics sawing program has been developed as a tool for modeling various hardwood processes, from bucking and topping to log sawing, lumber edging, secondary processing, and even veneering. The microcomputer platform makes the tool affordable and accessible. A solid modeling basis provides the tool with a sound geometrical...

  3. Tobacco Products

    Science.gov (United States)

    ... Exposure is High in Multiunit Housing Smokeless Products Electronic Cigarettes Youth Tobacco Prevention Tobacco Products Tobacco Ingredient ... Tweet Share Compartir Find Fact Sheets on Products (Cigars, Bidis and Betel Quid with Tobacco (Gutka) and ...

  4. Graphitization of diamond with a metallic coating on ferritic matrix; Grafitizacao do diamante com revestimento metalico em matriz ferritica

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Stenio Cavalier; Oliveira, Hellen Cristine Prata de; Filgueira, Marcello, E-mail: stenio@uenf.b [Universidade Estadual do Norte Fluminense (PPGECM/CCT/UENF), Campos dos Goytacazes, RJ (Brazil). Centro de Ciencias e Tecnologia. Programa de Pos Graduacao em Engenharia e Ciencia dos Materiais

    2010-07-01

    Iron is a strong catalyst of graphitization of diamonds. This graphitization occurs mainly during the processing of composites - conventional sintering or hot pressing, and during cutting operations. Aiming to avoid or minimize this deleterious effect, there is increasing use of diamond coated with metallic materials in the production of diamond tools processed via powder metallurgy. This work studies the influence of Fe on diamond graphitization diamond-coated Ti after mixing of Fe-diamonds, hot pressing parameters were performed with 3 minutes/35MPa/900 deg C - this is the condition of pressing hot used in industry for production of diamond tools. Microstructural features were observed by SEM, diffusion of Fe in diamond was studied by EDS. Graphitization was analyzed by X-ray diffraction and Raman spectroscopy. It was found that Fe not activate graphitization on the diamond under the conditions of hot pressing. (author)

  5. Graphitization of diamond with a metallic coating on ferritic matrix

    International Nuclear Information System (INIS)

    Cabral, Stenio Cavalier; Oliveira, Hellen Cristine Prata de; Filgueira, Marcello

    2010-01-01

    Iron is a strong catalyst of graphitization of diamonds. This graphitization occurs mainly during the processing of composites - conventional sintering or hot pressing, and during cutting operations. Aiming to avoid or minimize this deleterious effect, there is increasing use of diamond coated with metallic materials in the production of diamond tools processed via powder metallurgy. This work studies the influence of Fe on diamond graphitization diamond-coated Ti after mixing of Fe-diamonds, hot pressing parameters were performed with 3 minutes/35MPa/900 deg C - this is the condition of pressing hot used in industry for production of diamond tools. Microstructural features were observed by SEM, diffusion of Fe in diamond was studied by EDS. Graphitization was analyzed by X-ray diffraction and Raman spectroscopy. It was found that Fe not activate graphitization on the diamond under the conditions of hot pressing. (author)

  6. Synergistic methods for the production of high-strength and low-cost boron carbide

    Science.gov (United States)

    Wiley, Charles Schenck

    2011-12-01

    Boron carbide (B4C) is a non-oxide ceramic in the same class of nonmetallic hard materials as silicon carbide and diamond. The high hardness, high elastic modulus and low density of B4C make it a nearly ideal material for personnel and vehicular armor. B4C plates formed via hot-pressing are currently issued to U.S. soldiers and have exhibited excellent performance; however, hot-pressed articles contain inherent processing defects and are limited to simple geometries such as low-curvature plates. Recent advances in the pressureless sintering of B4C have produced theoretically-dense and complex-shape articles that also exhibit superior ballistic performance. However, the cost of this material is currently high due to the powder shape, size, and size distribution that are required, which limits the economic feasibility of producing such a product. Additionally, the low fracture toughness of pure boron carbide may have resulted in historically lower transition velocities (the projectile velocity range at which armor begins to fail) than competing silicon carbide ceramics in high-velocity long-rod tungsten penetrator tests. Lower fracture toughness also limits multi-hit protection capability. Consequently, these requirements motivated research into methods for improving the densification and fracture toughness of inexpensive boron carbide composites that could result in the development of a superior armor material that would also be cost-competitive with other high-performance ceramics. The primary objective of this research was to study the effect of titanium and carbon additives on the sintering and mechanical properties of inexpensive B4C powders. The boron carbide powder examined in this study was a sub-micron (0.6 mum median particle size) boron carbide powder produced by H.C. Starck GmbH via a jet milling process. A carbon source in the form of phenolic resin, and titanium additives in the form of 32 nm and 0.9 mum TiO2 powders were selected. Parametric studies of

  7. Light weight radioisotope heater unit (LWRHU) production for the Cassini mission

    International Nuclear Information System (INIS)

    Rinehart, G.H.

    1997-01-01

    The Light-Weight Radioisotope Heater Unit (LWRHU) is a [sup 238]PuO[sub 2] fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. The heat sources are required to maintain the temperature of specific components within normal operating ranges. The heat source consists of a hot- pressed [sup 238]PuO[sub 2] fuel pellet, a Pt-3ORh vented capsule, a pyrolytic graphite insulator, and a woven graphite aeroshell assembly. Los Alamos National Laboratory has fabricated 180 heat sources, 157 of which will be used on the Cassini mission

  8. Production of Modularised Product Systems

    DEFF Research Database (Denmark)

    Jacobsen, Peter

    2004-01-01

    but a solution. Modularisation is one tool used in designing the products. Designing and controlling a production system making customized products in an economical way is not an easy task. In order to fulfil the Lean and Agile manufacturing philosophies the production is often carried out in networks. Here...

  9. Product Customization

    DEFF Research Database (Denmark)

    Hvam, Lars; Mortensen, Niels Henrik; Riis, Jesper

    For the majority of industrial companies, customizing products and services is among the most critical means to deliver true customer value and achieve superior competitive advantage. The challenge is not to customize products and services in itself – but to do it in a profitable way...... from more than 40 product configuration projects in companies providing customer tailored products and services........ The implementation of a product configuration system is among the most powerful ways of achieving this in practice, offering a reduction of the lead time for products and quotations, faster and more qualified responses to customer inquiries, fewer transfers of responsibility and fewer specification mistakes...

  10. Workforce productivity.

    Science.gov (United States)

    Williams, Ruth

    2012-10-26

    Managers who are responsible for delivering the workforce productivity element of the Quality, Innovation, Productivity and Prevention (QIPP) programme can network and share best practice through a dedicated NHS Employers webpage.

  11. Primary productivity

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.; Parulekar, A.H.

    Photosynthetic production in the oceans in relation to light, nutrients and mixing processes is discussed. Primary productivity in the estuarine region is reported to be high in comparison to coastal and oceanic waters. Upwelling phenomenon...

  12. Immobilization of radioiodine in synthetic boracite

    Science.gov (United States)

    Babad, H.; Strachan, D.M.

    1982-09-23

    A nuclear waste storage product is disclosed in which radioiodine is incorporated in a synthetic boracite. The boracite may be prepared by reacting a transition metal iodide with an alkali horate under mild hydrothermal conditions, drying the reaction product, and then hot pressing.

  13. Product (RED)

    DEFF Research Database (Denmark)

    Ponte, Stefano

    2011-01-01

    ) and the consumers who buy iconic brand products to help ‘distant others’. While in many other forms of causumerism, labels or certification systems ‘prove’ that a product is just, in RED, aid celebrities provide the proof. From the consumer point of view both labels and celebrities provide a similar simplification...... of complex social, economic, and environmental processes. At the same time, we argue that there are important distinctions as well—labels and certifications are ultimately about improving the conditions of production, whereas RED is about accepting existing production and trade systems and donating......(PRODUCT)RED™ (hereafter RED) is a cobranding initiative launched in 2006 by the aid celebrity Bono to raise money from product sales to support The Global Fund to Fight AIDS, Tuberculosis and Malaria. In this paper we argue that RED is shifting the boundaries of ‘causumerism’ (shopping...

  14. Generalized product

    OpenAIRE

    Greco, Salvatore; Mesiar, Radko; Rindone, Fabio

    2014-01-01

    Aggregation functions on [0,1] with annihilator 0 can be seen as a generalized product on [0,1]. We study the generalized product on the bipolar scale [–1,1], stressing the axiomatic point of view. Based on newly introduced bipolar properties, such as the bipolar increasingness, bipolar unit element, bipolar idempotent element, several kinds of generalized bipolar product are introduced and studied. A special stress is put on bipolar semicopulas, bipolar quasi-copulas and bipolar copulas.

  15. Swine production.

    Science.gov (United States)

    Plain, Ronald L; Lawrence, John D

    2003-07-01

    The US swine industry is large and growing. The quantity of pork desired by consumers of US pork is growing at the rate of 1.5%/y. New production systems and new technology have enabled production per sow to grow at a rate of 4% annually in recent years. Consequently, the number of sows in the United States is declining. Because productivity growth is outpacing demand growth, the deflated price of hogs and pork is declining. Hog production and prices continue to exhibit strong seasonal and cyclic patterns. Pork production is usually lowest in the summer and highest in the fall. Production and prices tend to follow 4-year patterns. The US swine industry continues to evolve toward fewer and larger producers who rely on contracts for both hog production and marketing. In 2000, over half of the hogs marketed were from approximately 156 firms marketing more than 50,000 head annually. These producers finished 60% of their production in contract facilities. Over 90% of their marketings were under contract or were owned by a packer. These producers expressed a high level of satisfaction with hog production. Both they and their contract growers were satisfied with production contracts. These large producers were satisfied with their marketing contracts and planned to continue them in the future. The hog industry has changed a great deal in the last decade. There is little reason to believe this rapid rate of change will not continue. This swine industry is highly competitive and profit driven. Profit margins are too small to allow producers the luxury of ignoring new technology and innovative production systems. Consequently, hog production will continue its rapid evolution from traditional agriculture to typical industry.

  16. Classificação de lâminas de madeira de Pinus spp. contaminadas por fungos manchadores Classification of Pinus spp. veneers wood contaminated by blue stain fungi

    Directory of Open Access Journals (Sweden)

    Mayara Elita Carneiro

    2013-04-01

    Full Text Available A busca por novas tecnologias que garantam a uniformidade da qualidade dos produtos tem se tornado constante, assim este trabalho teve como objetivo estudar a potencialidade de medidas espectroscópicas combinadas a ferramentas estatísticas para classificação de lâminas de madeiras de Pinus spp. contaminadas por fungos manchadores. As amostras foram coletadas em processo industrial, e observou-se que algumas lâminas estavam contaminadas por fungos manchadores. Assim, utilizou-se este material para investigar a influência dessa mancha azul em metodologias espectroscópicas e a possibilidade de discriminação dessa contaminação. Desse material contaminado foram capturados os espectros, na faixa de 400 a 1000 nm. Com esses dados, realizou-se uma análise exploratória por Componentes Principais (PCA e classificação via SIMCA, em que se verificou a discriminação eficiente em dois grupos, madeiras sadias e contaminadas. Observou-se que a técnica de espectroscopia óptica preenche os requisitos necessários para uma possível aplicação na classificação de lâminas no processo produtivo.The search for new technologies that ensure uniformity of product quality has become constant. The objective of this work was to study the potential of spectroscopic measurements combined with statistical tools for sorting sheets of wood of Pinus spp. contaminated by staining fungi. Samples were collected in the industrial process and it was found that some blades were contaminated by fungus staining. Thus, this material was used to investigate its influence on blue stain and spectroscopic methods and the possibility of discrimination by such contamination. Spectra at 400-1000 m range were captured from this contaminated material. By using these data, it was performed an exploratory analysis by Principal Components (PCA and classification via SIMCA, where discrimination was found effective in healthy and diseased wood. It is observed that the use of

  17. Shaping-lathe roundup machine is key to profitable manufacturing of composite sheathing panels in Massachusetts or Maine

    Science.gov (United States)

    N. Springate; I. Plough; P. Koch

    1978-01-01

    A process is described in which a shaping-lathe headrig produces flakes of optimum geometry while rounding 8-foot peeler bolts to their maximum cylindrical diameter. The cylinders are then passed, at a rate of 5 to 7 per minute, to a veneer lathe for production of continuoua veneer, which is subsequently clipped into 4- by 8-foot sheets. Veneer cores are flaked in a...

  18. Shaping-lathe roundup machine is key to profitable manufacture of composite sheathing panels in Massachusetts or Maine

    Science.gov (United States)

    Norman Springate; Peter Koch; Irving Plough

    1978-01-01

    A process is described in which a shaping-lathe headrig produces flakes of optimum geometry while rounding 8-foot peeler bolts to their maximum cylindrical diameter. The cylinder are then passed, at a rate of 5 to 7 per minute, to a veneer lathe for production of continuous veneer, which is Subsequently clipped into 4- by 8-foot sheet.. Veneer cores are flaked in a...

  19. Antiproton production

    International Nuclear Information System (INIS)

    Allaby, J.V.

    1984-01-01

    The basic definitions used in the physics literature on particle production are reviewed. The data on anti p production are interpreted in order to provide an estimate of the yield of anti p's from typical target at the antiproton accumulator, including the effects of re-absorption in the target. (orig.)

  20. The reaction of sintered aluminium products with uranium dioxide and monocarbide

    DEFF Research Database (Denmark)

    Lauritzen, T.; Knudsen, Per

    1965-01-01

    The compatibility of SAP 930 with uranium dioxide and uranium monocarbide was investigated in the temperature range 450–600° C. The results indicate that a severe reaction occurs between SAP 930 and UO2 within 8000 hours at 600° C, a slight reaction at 600° C for 1000 hours and after 11 900 hours...... at 525° C, and no reaction in 14 300 hours at 450° C. Of the three grades of UC tested (hot pressed, arc cast, cold pressed and sintered) the slightly substoichiometric, hot-pressed UC is judged to be least compatible with SAP 930, reaction occurring after 7300 hours at 450° C. No reaction was observed...... between SAP 930 and the other carbides at this temperature. All SAP−UC combinations are incompatible at 600° C for as little as 100 hours of heat treatment. Tests designed to study the effect of a diffusion barrier on the SAP−UC reaction have shown that anodized SAP 930 and the three uranium carbides...

  1. Análise de risco e retorno do setor florestal: produtos da madeira Analysis of risk and return of the forest sector: wood products

    Directory of Open Access Journals (Sweden)

    Rommel Noce

    2005-02-01

    Full Text Available O presente trabalho objetivou descrever, analisar e comparar a relação risco/retorno dos produtos madeira serrada, madeira aplainada, madeira laminada, compensado e pasta química de madeira em função do comportamento de seu preço, durante as três últimas décadas, com base na taxa geométrica de crescimento e na dispersão dos preços. De acordo com os resultados, concluiu-se que os únicos produtos que apresentaram relação favorável à captação de recursos durante essas três décadas foram madeira serrada e madeira aplainada.This work aimed to describe, analyze and to compare the relation risk and return of the forest products: sawn wood, planed wood, veneer, plywood and the chemical pulpwood, in function of the behavior of its price, during the three last decades with base in the geometric rate of growth and in the price dispersion. The results indicated that the only products that presented favorable relation to fund raising, during the three decades, were the sawn and planed wood.

  2. Radioisotope production

    International Nuclear Information System (INIS)

    1988-01-01

    The trial production runs started in the previous report period were continued and have been extended to 67 Ga, 81 Rb/ 81m Kr and 111 In, the production of which will be taken over from the Pretoria cyclotron at the end of this year, when that machine is scheduled to be shut down. After commissioning of the target water cooling system and the helium cooling system for beam foil windows at the beginning of this year, these production runs could also be extended to high beam currents (up to 50 μA). Test consignments of a number of products have been supplied to various potential future users, and 123 I, in the form of Na 123 I capsules as well as 123 I-sodium hippurate, and 52 Fe-citrate have actually been used with success in trial diagnostic studies on patients. A procedure for labelling IPPA and 3-IPMPA with 123 I has been developed, while initial work has also been done on the radioiodination of monoclonal antifibrine antibodies. The last major facility needed for the commencement of the routine radioisotope production programme, namely the multiple-target facility, is now ready for installation in the production vault within the next few weeks, and routine production runs are expected to start in November 1988. 4 figs., 18 refs

  3. Ethanol production

    Energy Technology Data Exchange (ETDEWEB)

    Kolleurp, F; Daugulis, A J

    1985-05-01

    Extractive fermentation is a technique that can be used to reduce the effect of end-product inhibition through the use of a water-immiscible phase which removes fermentation products in situ. This has the beneficial effect of not only removing inhibitory products as they are formed (thus keeping reaction rates high) but also has the potential for reducing product recovery costs. We have chosen to examine the ethanol fermentation as a model system for end product inhibition and extractive fermentation, and have developed a computer model predicting the productivity enhancement possible with this technique. The model predicts an ethanol productivity of 82.6 g/L-h if a glucose feed of 750 g/L is fermented with a solvent having a distribution coefficient of 0.5 at a dilution rate of 5.0 h . This is more than 10 times higher than for a conventional chemostat fermentation of a 250 g/L glucose feed. In light of this, a systematic approach to extractive fermentation has been undertaken involving the screening of more than 1,000 solvents for their extractive properties. UNIFAC and UNIQUAC estimates of distribution coefficients and selectivities were compiled and ranked in a database, together with other important physical properties, such as density, surface tension and viscosity. Preliminary shake-flask and chemostat biocompatibility studies on the most promising solvents have been undertaken. The previous predictive, data base and experimental results are discussed.

  4. Product plots.

    Science.gov (United States)

    Wickham, Hadley; Hofmann, Heike

    2011-12-01

    We propose a new framework for visualising tables of counts, proportions and probabilities. We call our framework product plots, alluding to the computation of area as a product of height and width, and the statistical concept of generating a joint distribution from the product of conditional and marginal distributions. The framework, with extensions, is sufficient to encompass over 20 visualisations previously described in fields of statistical graphics and infovis, including bar charts, mosaic plots, treemaps, equal area plots and fluctuation diagrams. © 2011 IEEE

  5. Tanning Products

    Science.gov (United States)

    ... must obtain a signed, FDA-prescribed risk acknowledgement certification before use that states that they have been informed of the risks to health that may result from use of sunlamp products. Using tanning lamps, booths, or beds: If you ...

  6. Bc production

    International Nuclear Information System (INIS)

    Lusignoli, M.; Masetti, M.; Petrarca, S.

    1991-01-01

    The pseudoscalar meson B c is the simplest particle containing more than one heavy quark of different flavours. Its production cross sections at accelerators presently running or in project are estimated using the HERWIG parton shower Monte Carlo code. (orig.)

  7. Production models

    DEFF Research Database (Denmark)

    Svensson, Carsten

    2002-01-01

    The Project is co-financed with Nilpeter A/S and investigates the industrialization of build to order production. Project content: - Enterprise engineering - Specification processes - Mass Customization/ Build To Order - Knowledge/information management - Configuration - Supply Chain Management...

  8. Marketplace Products

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Office of Enterprise Data and Analytics, within the Centers for Medicare aqnd Medicaid Services (CMS), has developed a set of information products and analytics...

  9. Lean production

    OpenAIRE

    Veselková, Jana

    2011-01-01

    The goal of this Bachelor's Thesis is to describe the general principles of lean production and afterwards apply these principles in a particular company. Due to the changing conditions on the world market is among companies growing concern about such innovative business systems. The theoretical part of this work deals with the general characteristics of lean production, including their history and focus on Toyota, as the originator of most lean systems. Mentioned are also the economic aspect...

  10. Productive Gaming

    OpenAIRE

    Brandstätter , Ulrich; Sommerer , Christa

    2016-01-01

    Part 4: Short Papers; International audience; Video games can be appropriated for productive purposes. Commercial games and game engines are often used for video productions, and game development companies provide development kits and modding environments to gaming communities and independent developers. With gamification, game principles are deployed in non-game contexts for benefits beyond pure entertainment. Most approaches are more focused on using games and their design elements rather t...

  11. Manufacturing and process optimization of porous rice straw board

    Science.gov (United States)

    Liu, Dejun; Dong, Bing; Bai, Xuewei; Gao, Wei; Gong, Yuanjuan

    2018-03-01

    Development and utilization of straw resources and the production of straw board can dramatically reduce straw waste and environmental pollution associated with straw burning in China. However, the straw board production faces several challenges, such as improving the physical and mechanical properties, as well as eliminating its formaldehyde content. The recent research was to develop a new straw board compound adhesive containing both inorganic (MgSO4, MgCO3, active silicon and ALSiO4) and organic (bean gum and modified Methyl DiphenylDiisocyanate, MDI) gelling materials, to devise a new high frequency straw board hot pressing technique and to optimize the straw board production parameters. The results indicated that the key hot pressing parameters leading to porous straw board with optimal physical and mechanical properties. These parameters are as follows: an adhesive containing a 4:1 ratio of inorganic-to-organic gelled material, the percentage of adhesive in the total mass of preload straw materials is 40%, a hot-pressing temperature in the range of 120 °C to 140 °C, and a high frequency hot pressing for 10 times at a pressure of 30 MPa. Finally, the present work demonstrated that porous straw board fabricated under optimal manufacturing condition is an environmentally friendly and renewable materials, thereby meeting national standard of medium density fiberboard (MDF) with potential applications in the building industry.

  12. Biocidal Products and Borderline Products

    OpenAIRE

    Yılmaz, Abdullah

    2015-01-01

    Biocidal product is defined as preparations sold in ready form to use that contains one or more active substances and has control effect, movement restriction or destruction against harmful organisms which has harmful effect on products that people use or produce or animals or environment. These substances which are composed mostly chemicals and ease our lifes are used in increasingly every areas of our life on the other hand they carry variety of risks and threaten our lives. In terms of env...

  13. Environmental products

    International Nuclear Information System (INIS)

    1995-12-01

    This volume in the series of directories of Quebec organizations doing research and development involving biomass-based products or processes focused on environmental products and services. The objective of this, and other directories in the series, was to stimulate interaction, and hence more aggressive development, of products and processes capable of being commercialized, to facilitate interaction between those who possess and those who could utilize biomass resources, and in general, to encourage the development of biomass-based industries. A total of 83 organizations were included in standardized format, describing areas of research interest, principal areas of technological expertise, major equipment, personnel and name and address of contact person. In this volume fields of research interest included environmental audits, waste treatment, biodegradation, composting, oxidation, photodegradation, disinfection and combustion. tabs

  14. Uranium production

    International Nuclear Information System (INIS)

    Spriggs, M.

    1980-01-01

    The balance between uranium supply and demand is examined. Should new resources become necessary, some unconventional sources which could be considered include low-grade extensions to conventional deposits, certain types of intrusive rock, tuffs, and lake and sea-bed sediments. In addition there are large but very low grade deposits in carbonaceous shales, granites, and seawater. The possibility of recovery is discussed. Programmes of research into the feasibility of extraction of uranium from seawater, as a by-product from phosphoric acid production, and from copper leach solutions, are briefly discussed. Other possible sources are coal, old mine dumps and tailings, the latter being successfully exploited commercially in South Africa. The greatest constraints on increased development of U from lower grade sources are economics and environmental impact. It is concluded that apart from U as a by-product from phosphate, other sources are unlikely to contribute much to world requirements in the foreseeable future. (U.K.)

  15. Bottom production

    International Nuclear Information System (INIS)

    Baines, J.; Baranov, S.P.; Bartalini, P.; Bay, A.; Bouhova, E.; Cacciari, M.; Caner, A.; Coadou, Y.; Corti, G.; Damet, J.; Dell-Orso, R.; De Mello Neto, J.R.T.; Domenech, J.L.; Drollinger, V.; Eerola, P.; Ellis, N.; Epp, B.; Frixione, S.; Gadomski, S.; Gavrilenko, I.; Gennai, S.; George, S.; Ghete, V.M.; Guy, L.; Hasegawa, Y.; Iengo, P.; Jacholkowska, A.; Jones, R.; Kharchilava, A.; Kneringer, E.; Koppenburg, P.; Korsmo, H.; Kramer, M.; Labanca, N.; Lehto, M.; Maltoni, F.; Mangano, M.L.; Mele, S.; Nairz, A.M.; Nakada, T.; Nikitin, N.; Nisati, A.; Norrbin, E.; Palla, F.; Rizatdinova, F.; Robins, S.; Rousseau, D.; Sanchis-Lozano, M.A.; Shapiro, M.; Sherwood, P.; Smirnova, L.; Smizanska, M.; Starodumov, A.; Stepanov, N.; Vogt, R.

    2000-01-01

    In the context of the LHC experiments, the physics of bottom flavoured hadrons enters in different contexts. It can be used for QCD tests, it affects the possibilities of B decays studies, and it is an important source of background for several processes of interest. The physics of b production at hadron colliders has a rather long story, dating back to its first observation in the UA1 experiment. Subsequently, b production has been studied at the Tevatron. Besides the transverse momentum spectrum of a single b, it has also become possible, in recent time, to study correlations in the production characteristics of the b and the b. At the LHC new opportunities will be offered by the high statistics and the high energy reach. One expects to be able to study the transverse momentum spectrum at higher transverse momenta, and also to exploit the large statistics to perform more accurate studies of correlations

  16. Bottom production

    Energy Technology Data Exchange (ETDEWEB)

    Baines, J.; Baranov, S.P.; Bartalini, P.; Bay, A.; Bouhova, E.; Cacciari, M.; Caner, A.; Coadou, Y.; Corti, G.; Damet, J.; Dell-Orso, R.; De Mello Neto, J.R.T.; Domenech, J.L.; Drollinger, V.; Eerola, P.; Ellis, N.; Epp, B.; Frixione, S.; Gadomski, S.; Gavrilenko, I.; Gennai, S.; George, S.; Ghete, V.M.; Guy, L.; Hasegawa, Y.; Iengo, P.; Jacholkowska, A.; Jones, R.; Kharchilava, A.; Kneringer, E.; Koppenburg, P.; Korsmo, H.; Kramer, M.; Labanca, N.; Lehto, M.; Maltoni, F.; Mangano, M.L.; Mele, S.; Nairz, A.M.; Nakada, T.; Nikitin, N.; Nisati, A.; Norrbin, E.; Palla, F.; Rizatdinova, F.; Robins, S.; Rousseau, D.; Sanchis-Lozano, M.A.; Shapiro, M.; Sherwood, P.; Smirnova, L.; Smizanska, M.; Starodumov, A.; Stepanov, N.; Vogt, R.

    2000-03-15

    In the context of the LHC experiments, the physics of bottom flavoured hadrons enters in different contexts. It can be used for QCD tests, it affects the possibilities of B decays studies, and it is an important source of background for several processes of interest. The physics of b production at hadron colliders has a rather long story, dating back to its first observation in the UA1 experiment. Subsequently, b production has been studied at the Tevatron. Besides the transverse momentum spectrum of a single b, it has also become possible, in recent time, to study correlations in the production characteristics of the b and the b. At the LHC new opportunities will be offered by the high statistics and the high energy reach. One expects to be able to study the transverse momentum spectrum at higher transverse momenta, and also to exploit the large statistics to perform more accurate studies of correlations.

  17. Phytosanitary products

    International Nuclear Information System (INIS)

    1995-12-01

    One of a series of directories of Quebec universities, industrial and governmental agencies in Quebec actively involved in research and development of phytosanitary products or services derived from or associated with biomass products. This directory contained standardized entries for 79 organizations from the agriculture, forestry and environmental sectors, active in fields ranging from genetic engineering, fertilizers, crop diseases and pest management, forestry management, harvesting methods and bioconversion. Each entry provided information about major fields of research interest, principal technologies utilized, major equipment, personnel, and name and address of person to be contacted for further information. tabs

  18. Aluminium production

    International Nuclear Information System (INIS)

    Winter, B.; Ayers, J.; Sammer, G.

    2001-01-01

    Aluminium is the most important non-ferrous metal by quantity. Aluminium is produced by electrolysis of aluminium oxide (also known as alumina). Alumina is produced by refining bauxite. The quantity of primary and secondary aluminium production in ECE-countries between 1992 and 1998 is shown. The European aluminium industry employs approximately 200 000 employees. The annual aluminium production in the European Union was 3.58 million tonnes in 1994, of which 44 % was secondary aluminium. In 1996 3.96 million tonnes of aluminium were produced in the EU, of which 44 % was secondary aluminium. (author)

  19. Uranium production

    International Nuclear Information System (INIS)

    Jones, J.Q.

    1981-01-01

    The domestic uranium industry is in a state of stagflation. Costs continue to rise while the market for the product remains stagnant. During the last 12 months, curtailments and closures of mines and mills have eliminated over 5000 jobs in the industry, plus many more in those industries that furnish supplies and services. By January 1982, operations at four mills and the mines that furnish them ore will have been terminated. Other closures may follow, depending on cost trends, duration of current contracts, the degree to which mills have been amortized, the feasibility of placing mines on standby, the grade of the ore, and many other factors. Open-pit mines can be placed on standby without much difficulty, other than the possible cost of restoration before all the ore has been removed. There are a few small, dry, underground mines that could be mothballed; however, the major underground producers are wet sandstone mines that in most cases could not be reopened after a prolonged shutdown; mills can be mothballed for several years. Figure 8 shows the location of all the production centers in operation, as well as those that have operated or are on standby. Table 1 lists the same production centers plus those that have been deferred, showing nominal capacity of conventional mills in tons of ore per calendar day, and the industry production rate for those mills as of October 1, 1981

  20. Novolak Production

    Science.gov (United States)

    Aiba, Hiroshi

    Novolak resins are produced by reacting formaldehyde (30-55% concentration) with phenol under acidic conditions, with oxalic acid as the preferred catalyst and in special conditions, sulfuric acid. Depending on the batch size, all raw material components can be introduced into the reactor, or when there is an increase in the batch size as well as in the reactor volume, the reaction exotherm is controlled by a gradual addition of formaldehyde. Modern novolak production facilities are automated and programmed for reduced operational cost. A flow diagram of a general production line for the manufacture of novolak is shown. Recovery of the novolak is accomplished by the removal of water and devolatilization of crude novolak to molten, low-free phenol novolak resin which can be isolated as flake or pastille or dissolved in appropriate solvents. Novolak is stored either in a solid flake or pastille form or in solution. Most production is conducted under atmospheric conditions, but there are some recent, novel activities such as pressure in a hermetically-closed reactor reaching 0.1-10 MPa by using the heat of reaction without reflux to shorten reaction time, accelerating dehydration time by flash distillation, and providing economic benefit in the cost of novolak production.

  1. Bipolar plates for polymer electrolyte membrane fuel cells made of thermal and electrical high conductivity thermoplastics. Formulation, production, characterization and application; Bipolarplatten fuer Polymerelektrolytmembran-Brennstoffzellen aus thermisch und elektrisch hochleitfaehigen thermoplastischen Kunststoffen. Rezeptierung, Herstellung, Charakterisierung und Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Ralf Leonhard

    2008-07-01

    The upcoming lack of primary energy sources and the need of reducing the anthropogenic climate change led to increased research activities in the field of Fuel Cells (FC) technology within the last ten years in Europe, the USA and Japan. Especially the automotive industry is highly interested in developing zero emission cars as a replacement of nowadays cars within the next twenty years. Not only for mobile applications the Polymer Electrolyte Membrane Fuel Cell systems (PEM-FC systems) is the focus of research and development. Also stationary (PEM-) FC applications seem to be more and more interesting for a decentralized energy supply, producing electricity and heat (Vaillant FC-Systems, Bosch/Junkers). For this purpose, system miniaturizing and weight reduction (70-90 wt-% of the stack itself is due to bipolar- and endplate) is not that essential as it is for mobile appliance, resulting in earlier commercial market introduction of these systems within the next few years. Not only the weight reduction of the FC-stack itself, but also the cost cutting of its components is vital for the economic success of this technology. The three most expensive components of the stack are the perfluorsulfonated ion conducting Membranen (PEM: Nafion, Ashai, Ashai glass), the noble metal catalyst (Platinum and/or Ruthenium) and the Bipolar Plate (BPP). The moulding processes (injection and/or compression moulding) of polymer materials allow highly integrated, tool reduced mass production of tailored stack components like the BP, the endplate, cell frame and peripheral components. The objective of this thesis is to describe the development of an conductive functionalised material suitable for moulding BPP, to investigate compounding optimisation methods (DOE) and evaluate the best fit parameters, to analyse the rheological behaviour of these highly filled compounds, to discuss suitable polymer related manufacturing processes like hot pressing, injection moulding and profile

  2. Biofilm architecture of Phanerozoic cryptic carbonate marine veneers

    Science.gov (United States)

    Riding, Robert

    2002-01-01

    Thin (mushrooms, and plumes. All can be interpreted as characteristics of attached bacterial communities, i.e., aggregates as microcolonies, originally embedded in a matrix of extracellular polymeric substances; channels as water conduits and/or uncolonized nutrient-poor spaces; external protuberances as localized growths; and plumes as surface streamers. Cryptic habitat favored pristine biofilm preservation by precluding disturbance and overgrowth, and suggests aphotic and anoxic conditions. These examples provide diagnostic morphologic criteria for wider recognition of biofilm in Phanerozoic and older carbonates.

  3. Design of Multiple Bolted Connections for Laminated Veneer Lumber

    Science.gov (United States)

    Borjen Yeh; Douglas Rammer; Jeff Linville

    2014-01-01

    The design of multiple bolted connections in accordance with Appendix E of the National Design Specification for Wood Construction (NDS) has incorporated provisions for evaluating localized member failure modes of row and group tear-out when the connections are closely spaced. Originally based on structural glued laminated timber (glulam) members made with all L1...

  4. Indirect veneer treatment of anterior maxillary teeth with enamel hypoplasia

    OpenAIRE

    Juniarti, Devi Eka

    2010-01-01

    Background: Nowadays, aesthetic rehabilitation becomes a necessity. It is affected by patient’s background, especially career, social and economic status. The aesthetic abnormality of anterior teeth i.e discoloration, malposition and malformation can affect patient’s appearance, especially during smile. These dental abnormalities, as a result, can decrease patient’s performance. Dental malformation, for instance, can be caused by developmental tooth defect, such as enamel hypoplasia. Enamel h...

  5. Product Configuration Systems and Productivity

    DEFF Research Database (Denmark)

    Pedersen, Jørgen Lindgaard; Edwards, Kasper

    2004-01-01

    Twelve companies have been interviewed with the purpose to get information about technical, economic and organisational matters in respect of Product Configuration Systems (PCS).Combinations of qualitative interviews and quantitative scoring have been used in ranking expected and realized results...

  6. Tequila production.

    Science.gov (United States)

    Cedeño, M

    1995-01-01

    Tequila is obtained from the distillation of fermented juice of agave plant, Agave tequilana, to which up to 49% (w/v) of an adjunct sugar, mainly from cane or corn, could be added. Agave plants require from 8 to 12 years to mature and during all this time cleaning, pest control, and slacken of land are required to produce an initial raw material with the appropriate chemical composition for tequila production. Production process comprises four steps: cooking to hydrolyze inulin into fructose, milling to extract the sugars, fermentation with a strain of Saccharomyces cerevisiae to convert the sugars into ethanol and organoleptic compounds, and, finally, a two-step distillation process. Maturation, if needed, is carried out in white oak barrels to obtain rested or aged tequila in 2 or 12 months, respectively.

  7. Lepton production

    CERN Multimedia

    2002-01-01

    This experiment aims to settle open questions in the hadronic production of electrons, muons and neutrinos. Prominent among these are $e/\\mu$ universality, the contribution of charm decay to lepton pair production, and the "anomalous" low mass pairs.\\\\ The experimental design aims to optimize the combination of:\\\\- electron identification\\\\ - muon identification \\\\ - missing energy measurement for neutrinos \\\\ - vertex identification (for $\\tau \\simeq \\tau_{charm}$). \\\\ \\\\ The major components of the apparatus are shown in the figure. In the vertex region a proton beam of transverse size $\\simeq 50 \\mu$ impinges on a beryllium target of diameter $50 \\mu$, and high precision tracking in the vertex region is achieved by silicon strip detectors. Charged particle momenta are measured using a dipole magnet and high resolution drift chambers. Electrons are identified by the combination of the transition radiation detector and the finely segmented front section of the Uranium/Liquid Argon calorimeter. Essentially t...

  8. Product customization

    DEFF Research Database (Denmark)

    Lueg, Rainer

    2015-01-01

    This case study deals with the extension, customization, and profitability of two new product lines of a bicycle manufacturer. It can serve both as a discussion basis in class as well as an exam for advanced Master students in management, marketing, and ccounting. The case illustrates how variance...... application of financial analysis can lead to dysfunctional decisions that run counter to a company’s business model....

  9. Isotope production

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Dewi M.

    1995-07-15

    Some 2 0% of patients using radiopharmaceuticals receive injections of materials produced by cyclotrons. There are over 200 cyclotrons worldwide; around 35 are operated by commercial companies solely for the production of radio-pharmaceuticals with another 25 accelerators producing medically useful isotopes. These neutron-deficient isotopes are usually produced by proton bombardment. All commonly used medical isotopes can be generated by 'compact' cyclotrons with energies up to 40 MeV and beam intensities in the range 50 to 400 microamps. Specially designed target systems contain gram-quantities of highly enriched stable isotopes as starting materials. The targets can accommodate the high power densities of the proton beams and are designed for automated remote handling. The complete manufacturing cycle includes large-scale target production, isotope generation by cyclotron beam bombardment, radio-chemical extraction, pharmaceutical dispensing, raw material recovery, and labelling/packaging prior to the rapid delivery of these short-lived products. All these manufacturing steps adhere to the pharmaceutical industry standards of Good Manufacturing Practice (GMP). Unlike research accelerators, commercial cyclotrons are customized 'compact' machines usually supplied by specialist companies such as IBA (Belgium), EBCO (Canada) or Scanditronix (Sweden). The design criteria for these commercial cyclotrons are - small magnet dimensions, power-efficient operation of magnet and radiofrequency systems, high intensity extracted proton beams, well defined beam size and automated computer control. Performance requirements include rapid startup and shutdown, high reliability to support the daily production of short-lived isotopes and low maintenance to minimize the radiation dose to personnel. In 1987 a major step forward in meeting these exacting industrial requirements came when IBA, together with the University of Louvain-La-Neuve in Belgium, developed the Cyclone-30

  10. Diboson production

    Directory of Open Access Journals (Sweden)

    Evans D.L.

    2013-05-01

    Full Text Available Measurements of diboson production cross sections in pp collisions at the LHC at a centre of mass energy √s = 7 and 8 TeV, and in pp̅ collisions at the Tevatron at √s = 1.96 TeV are reviewed and compared with standard model predictions. Limits on charged and neutral anomalous triple gauge couplings extracted from the selected diboson event samples are also compared.

  11. Product design - Molecules, devices, functional products, and formulated products

    DEFF Research Database (Denmark)

    Gani, Rafiqul; Ng, Ka M.

    2015-01-01

    Chemical product design is a multidisciplinary and diverse subject. This article provides an overview of product design while focusing on product conceptualization. Four product types are considered - molecular products, formulated products, devices and functional products. For molecular products......, computer-aided design tools are used to predict the physicochemical properties of single molecules and blends. For formulated products, an integrated experiment-modeling approach is used to generate the formula with the specified product attributes. For devices and functional products, conceptual product...... design is carried out by modeling the product based on thermodynamics, kinetics and transport processes, by performing experiments, and by decision making based on rule-based methods The results are product specifications in terms of the type of ingredients, composition, and the structure, form, shape...

  12. New Product

    Institute of Scientific and Technical Information of China (English)

    铭瑄

    2012-01-01

    Double Coin Holdings Launch New OTR Tire REM-15 With the increase of the demand for large-scale bulldozer in American market, Double Coin Group Co., Ltd. developed the Double Coin REM-15 OTR tire. This product is applicable for large-scale loader and bulldozer. The most remarkable characteristic is that it has good energy-saving performance and durability with low operating cost while the performances of tires aren't lowered. The new REM-15 is currently offered in the 17.5R25 size, which will be expanded to larger sizes in the future.

  13. production lines

    Directory of Open Access Journals (Sweden)

    Jingshan Li

    2000-01-01

    Full Text Available In this work, serial production lines with finished goods buffers operating in the pull regime are considered. The machines are assumed to obey Bernoulli reliability model. The problem of satisfying customers demand is addressed. The level of demand satisfaction is quantified by the due-time performance (DTP, which is defined as the probability to ship to the customer a required number of parts during a fixed time interval. Within this scenario, the definitions of DTP bottlenecks are introduced and a method for their identification is developed.

  14. Bottom Production

    CERN Document Server

    Nason, P.; Schneider, O.; Tartarelli, G.F.; Vikas, P.; Baines, J.; Baranov, S.P.; Bartalini, P.; Bay, A.; Bouhova, E.; Cacciari, M.; Caner, A.; Coadou, Y.; Corti, G.; Damet, J.; Dell'Orso, R.; De Mello Neto, J.R.T.; Domenech, J.L.; Drollinger, V.; Eerola, P.; Ellis, N.; Epp, B.; Frixione, S.; Gadomski, S.; Gavrilenko, I.; Gennai, S.; George, S.; Ghete, V.M.; Guy, L.; Hasegawa, Y.; Iengo, P.; Jacholkowska, A.; Jones, R.; Kharchilava, A.; Kneringer, E.; Koppenburg, P.; Korsmo, H.; Kramer, M.; Labanca, N.; Lehto, M.; Maltoni, F.; Mangano, Michelangelo L.; Mele, S.; Nairz, A.M.; Nakada, T.; Nikitin, N.; Nisati, A.; Norrbin, E.; Palla, F.; Rizatdinova, F.; Robins, S.; Rousseau, D.; Sanchis-Lozano, M.A.; Shapiro, M.; Sherwood, P.; Smirnova, L.; Smizanska, M.; Starodumov, A.; Stepanov, N.; Vogt, R.

    2000-01-01

    We review the prospects for bottom production physics at the LHC. Members of the working group who has contributed to this document are: J. Baines, S.P. Baranov, P. Bartalini, A. Bay, E. Bouhova, M. Cacciari, A. Caner, Y. Coadou, G. Corti, J. Damet, R. Dell'Orso, J.R.T. De Mello Neto, J.L. Domenech, V. Drollinger, P. Eerola, N. Ellis, B. Epp, S. Frixione, S. Gadomski, I. Gavrilenko, S. Gennai, S. George, V.M. Ghete, L. Guy, Y. Hasegawa, P. Iengo, A. Jacholkowska, R. Jones, A. Kharchilava, E. Kneringer, P. Koppenburg, H. Korsmo, M. Kraemer, N. Labanca, M. Lehto, F. Maltoni, M.L. Mangano, S. Mele, A.M. Nairz, T. Nakada, N. Nikitin, A. Nisati, E. Norrbin, F. Palla, F. Rizatdinova, S. Robins, D. Rousseau, M.A. Sanchis-Lozano, M. Shapiro, P. Sherwood, L. Smirnova, M. Smizanska, A. Starodumov, N. Stepanov, R. Vogt

  15. Production management (1976)

    International Nuclear Information System (INIS)

    Lee, Sun Ryong

    1976-03-01

    This book introduces production management theory, which gives descriptions of production and system, systems approach, development of production management, Taylor system, Ford system, types of production system, measuring ingredients model of production management, decision of production management, selection of production facilities, arrangement of facilities design of work method and task, work measure system, demanding fore casting, production quality system and credibility system.

  16. From Product Models to Product State Models

    DEFF Research Database (Denmark)

    Larsen, Michael Holm

    1999-01-01

    A well-known technology designed to handle product data is Product Models. Product Models are in their current form not able to handle all types of product state information. Hence, the concept of a Product State Model (PSM) is proposed. The PSM and in particular how to model a PSM is the Research...

  17. Tobacco Products Production and Operations Reports

    Data.gov (United States)

    Department of the Treasury — Monthly statistical reports on tobacco products production and operations. Data for Tobacco Statistical Release is derived directly from the Report – Manufacturer of...

  18. Innovation in Product Development

    DEFF Research Database (Denmark)

    McAloone, Tim C.; Restrepo-Giraldo, John Dairo

    2005-01-01

    The course on Innovation in Product Development attempts to identify and understand the nature of innovation and product development and their important factors. The course takes both a theoretical and a practical approach and employs a mix of lectures, project work and group discussion. Format...... insight. Course content The following aspects of innovation in product development are considered: - Humans and products - Needs and products - Product life - Teams creating products - Products creating business - Product development models - Organising product development - Product development tools...... - The future of product development....

  19. SaferProducts API

    Data.gov (United States)

    US Consumer Product Safety Commission — On March 11, 2011, the U.S. Consumer Product Safety Commission launched SaferProducts.gov. This site hosts the agency's new Publicly Available Consumer Product...

  20. Product and labour market regulations, production prices, wages and productivity

    NARCIS (Netherlands)

    Cette, G.; Lopez, J.; Mairesse, J.

    2015-01-01

    This study is an attempt to evaluate the effects of product and labour market regulations on industry productivity through their various impacts on changes in production prices and wages. In a first stage, the estimation of a regression equation on an industry*country panel, with controls for

  1. Production management (2000)

    International Nuclear Information System (INIS)

    Jung, Chung Yeong

    2000-08-01

    This book includes basic concept of production management, production system, strategy and mission of production, decision of production management, operation of decision making, life cycle of items and development, value of productions, design for reliability of productions, equipment layout and manufacturing process, quantitative forecast, schedule plan, inventory system, concept, input and output of MRP, Montekalo simulation, quality management, and automation system.

  2. Product Service Systems

    DEFF Research Database (Denmark)

    Departing from Product Development models based on physical artefacts. Moving towards integrated Product Development and System Operations models suited Product/Service-systems......Departing from Product Development models based on physical artefacts. Moving towards integrated Product Development and System Operations models suited Product/Service-systems...

  3. Improving Dryer and Press Efficiencies Through Combustion of Hydrocarbon Emissions

    Energy Technology Data Exchange (ETDEWEB)

    Sujit Banerjee

    2005-10-31

    Emission control devices on dryers and presses have been legislated into the industry, and are now an integral part of the drying system. These devices consume large quantities of natural gas and electricity and down-sizing or eliminating them will provide major energy savings. The principal strategy taken here focuses on developing process changes that should minimize (and in some cases eliminate) the need for controls. A second approach is to develop lower-cost control options. It has been shown in laboratory and full-scale work that Hazardous Air Pollutants (HAPs) emerge mainly at the end of the press cycle for particleboard, and, by extension, to other prod-ucts. Hence, only the air associated with this point of the cycle need be captured and treated. A model for estimating terpene emissions in the various zones of veneer dryers has been developed. This should allow the emissions to be concentrated in some zones and minimized in others, so that some of the air could be directly released without controls. Low-cost catalysts have been developed for controlling HAPs from dryers and presses. Catalysts conventionally used for regenerative catalytic oxidizers can be used at much lower temperatures for treating press emissions. Fluidized wood ash is an especially inexpensive mate-rial for efficiently reducing formaldehyde in dryer emissions. A heat transfer model for estimating pinene emissions from hot-pressing strand for the manufacture of flakeboard has been constructed from first principles and validated. The model shows that most of the emissions originate from the 1-mm layer of wood adjoining the platen surface. Hence, a simple control option is to surface a softwood mat with a layer of hardwood prior to pressing. Fines release a disproportionate large quantity of HAPs, and it has been shown both theo-retically and in full-scale work that particles smaller than 400 µm are principally responsible. Georgia-Pacific is considering green

  4. Production of UT Reference Blocks Containing Artificially Introduced Defects

    International Nuclear Information System (INIS)

    Kaya, A. A.; Ucuncuoglu, S.; Kurkcu, N.; Kandemir, A.; Arslan, H.

    2007-01-01

    Metallic blocks of Inconel 718 and Ti-6A1-4V alloys that contain artificially introduced defects of known type, size, shape and location were prepared to serve as calibration standards in ultrasonic inspection. The synthetic defects employed to serve as reflectors were all pertinent to the specific alloy systems used, i.e. compositional defects termed as 'dirty white' 'white spot' and 'freckle' for Inconel 718; 'hard-alpha' for titanium alloy. Furthermore, as a defect type common to all three materials, spherical voids of various sizes were also incorporated into these calibration blocks. The aim of this study is to introduce defects of known type and size into metallic blocks made of superalloy Inconel 718 and titanium Ti-6A1-4V alloy. The scope of the study entailed determination of the correct parameters for manufacturing processes involved. Based on the results of the preceding phases of this study, it was decided that the method of Vacuum Hot Pressing (VHP) was to be used in this project to manufacture the metallic block containing artificial defects

  5. Production monitoring system for understanding product robustness

    DEFF Research Database (Denmark)

    Boorla, Srinivasa Murthy; Howard, Thomas J.

    2016-01-01

    study is used to demonstrate how the monitoring system can be used to efficiently guide corrective action to improve product performance. It is claimed that the monitoring system can be used to dramatically cut the time taken to identify, planand execute corrective action related to typical quality......In the current quality paradigm, the performance of a product is kept within specification by ensuring that its parts are within specification. Product performance is then validated after final assembly. However, this does not control how robust the product performance is, i.e. how much...... it will vary between the specification limits. In this paper, a model for predicting product performance is proposed, taking into account design, assembly and process parameters live from production. This empowers production to maintain final product performance, instead of part quality. The PRECI‐IN case...

  6. Productivity and Performance Measurement

    DEFF Research Database (Denmark)

    Hald, Kim Sundtoft; Spring, Martin

    This study explores conceptually how performance measurement as discussed in the literature, enables or constrains the ability to manage and improve productivity. It uses an inter-disciplinary literature review to identify five areas of concern relating productivity accounting to the ability...... to improve productivity: “Productivity representation”; “productivity incentives”, “productivity intervention”; “productivity trade-off or synergy” and “productivity strategy and context”. The paper discusses these areas of concern and expands our knowledge of how productivity and performance measurement...

  7. Product Structure, the Heart of Product Definition

    Science.gov (United States)

    DeHoog, C., Jr.

    1999-01-01

    This paper describes the LMMSS Product Definition System (PDS) philosophy and approach were the use of each item parts document or software can be traced to a specific end item (EI) serial/tail number of the product. It explains why a part-oriented approach to data organization and configuration management is required. The definition of part-oriented is that all appropriate product definition data products will be collected. Referenced and managed by their linkage/relationship to parts/items, The paper will touch upon how LMMSS store/controls product definition information under each project's top product designator in a two tiered approach. One tier for each product end item and another tier which contain/controls listings of drawings, documents. Specifications and standards that are required for hardware item definition.

  8. Heavy Flavour Production

    CERN Document Server

    Nason, Paolo; Ridolfi, Giovanni

    1995-01-01

    We review the status of heavy flavour production in QCD. Comparison of experimental and theoretical results for top and bottom production are given. Selected topics in charm production are also discussed.

  9. Animal Product Safety Information

    Science.gov (United States)

    ... Home Animal & Veterinary Safety & Health Product Safety Information Product Safety Information Share Tweet Linkedin Pin it More ... to report adverse experiences with veterinary drugs. Additional Product Information Questions and Answers: Evanger’s Dog and Cat ...

  10. Urinary incontinence products

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003973.htm Urinary incontinence products To use the sharing features on this ... There are many products to help you manage urinary incontinence . You can decide which product to choose based ...

  11. Production and characterization of bio plastics from potato starch, poly-hydroxybutyrate and poly-hydroxybutyrate-co-valerate

    International Nuclear Information System (INIS)

    Mendes, Fernanda M.; Curvelo, Antonio A.S.

    2009-01-01

    This work describes the study of thermoplastic starch (TPS) blends obtained from potato starch (plasticised with glycerol) with biodegradable polymers poly-hydroxybutyrate (PHB) and poly-hydroxybutyrate-co-valerate (PHB V). For this purpose it were developed several formulations with TPS/PHB, TPS/PHB V and TPS/PHB/PHB V prepared by physical mixing and water and glycerol as plasticizers. The amount of glycerol was 30% based on starch (dry basis). The starting materials (starch, PHB and PHB V) were characterized by scanning electron microscopy and X-ray diffraction. Then, it was determined the optimal processing conditions for the samples, performed by using an intensive mixer. The materials were hot pressed to produce the standardized samples employed in the characterizations: mechanical testing (tensile strength), dynamic-mechanical thermal analysis (DMTA), scanning electron microscopy and X-ray diffractometry. (author)

  12. COTTAGE CHEESE PRODUCTS FUNCTIONALITY

    Directory of Open Access Journals (Sweden)

    L. V. Golubeva

    2015-01-01

    Full Text Available Cottage cheese products holds a significant place among the dairy and milk-containing products. The range of products includes cheese: cheese, pastes, creams, cakes, etc. Such diversity can be attributed to their popularity among the population and benefit brought by the body from regular use. Curd protein is much better and easier to digest by the body than protein fish, meat or milk. Rich curd products lysine and methionine. Minerals contained in cheese products have a positive effect on bone formation and structure of tissues. The composition of curd products, in addition to cheese and dairy ingredients may include non-dairy ingredients origin. Today, for the production of cheese products use the most advanced technologies to further enrich its structure and significantly improve the nutritional value. Pine nut is widely used in the manufacture of many dairy products. But, in most cases, the production of dairy products as a filler used pine nut cake, which deprives the finished product valuable cedar oil. The authors proposed a technology for producing curd product with the addition of pine nuts and honey (pine nuts and fructose. Compatible with cream cheese filling insertion determined sensory organoleptic point scale. he optimum dosage of components: pine nuts – 5 %, honey – 10 % fructose – 7 %. Technological process of cottage cheese product is different from the traditional operations training components and their introduction into the finished cheese. Identify indicators of quality of the new product. Production of curd products thus expanding the range of dairy products functional orientation.

  13. Overview of mineral waste form development for the electrometallurgical treatment of spent nuclear fuel

    International Nuclear Information System (INIS)

    Pereira, C.; Lewis, M.A.; Ackerman, J.P.

    1996-01-01

    Argonne is developing a method to treat spent nuclear fuel in a molten salt electrorefiner. Wastes from this treatment will be converted into metal and mineral forms for geologic disposal. A glass-bonded zeolite is being developed to serve as the mineral waste form that will contain the fission products that accumulate in the electrorefiner salt. Fission products are ion exchanged from the salt into the zeolite A structure. The crystal structure of the zeolite after ion exchange is filled with salt ions. The salt-loaded zeolite A is mixed with glass frit and hot pressed. During hot pressing, the zeolite A may be converted to sodalite which also retains the waste salt. The glass-bonded zeolite is leach resistant. MCC-1 testing has shown that it has a release rate below 1 g/(m 2 day) for all elements

  14. Evaluation of the effect of tooth and dental restoration material on electron dose distribution and production of photon contamination in electron beam radiotherapy.

    Science.gov (United States)

    Bahreyni Toossi, Mohammad Taghi; Ghorbani, Mahdi; Akbari, Fatemeh; Mehrpouyan, Mohammad; Sobhkhiz Sabet, Leila

    2016-03-01

    The aim of this study is to evaluate the effect of tooth and dental restoration materials on electron dose distribution and photon contamination production in electron beams of a medical linac. This evaluation was performed on 8, 12 and 14 MeV electron beams of a Siemens Primus linac. MCNPX Monte Carlo code was utilized and a 10 × 10 cm(2) applicator was simulated in the cases of tooth and combinations of tooth and Ceramco C3 ceramic veneer, tooth and Eclipse alloy and tooth and amalgam restoration materials in a soft tissue phantom. The relative electron and photon contamination doses were calculated for these materials. The presence of tooth and dental restoration material changed the electron dose distribution and photon contamination in phantom, depending on the type of the restoration material and electron beam's energy. The maximum relative electron dose was 1.07 in the presence of tooth including amalgam for 14 MeV electron beam. When 100.00 cGy was prescribed for the reference point, the maximum absolute electron dose was 105.10 cGy in the presence of amalgam for 12 MeV electron beam and the maximum absolute photon contamination dose was 376.67 μGy for tooth in 14 MeV electron beam. The change in electron dose distribution should be considered in treatment planning, when teeth are irradiated in electron beam radiotherapy. If treatment planning can be performed in such a way that the teeth are excluded from primary irradiation, the potential errors in dose delivery to the tumour and normal tissues can be avoided.

  15. Evaluation of the effect of tooth and dental restoration material on electron dose distribution and production of photon contamination in electron beam radiotherapy

    International Nuclear Information System (INIS)

    Bahreyni Toossi, M.T.; Ghorbani, Mahdi; Akbari, Fatemah; Sabet, Leila S.; Mehrpouyan, Mohammad

    2016-01-01

    The aim of this study is to evaluate the effect of tooth and dental restoration materials on electron dose distribution and photon contamination production in electron beams of a medical linac. This evaluation was performed on 8, 12 and 14 MeV electron beams of a Siemens Primus linac. MCNPX Monte Carlo code was utilized and a 10 × 10 cm 2 applicator was simulated in the cases of tooth and combinations of tooth and Ceramco C3 ceramic veneer, tooth and Eclipse alloy and tooth and amalgam restoration materials in a soft tissue phantom. The relative electron and photon contamination doses were calculated for these materials. The presence of tooth and dental restoration material changed the electron dose distribution and photon contamination in phantom, depending on the type of the restoration material and electron beam’s energy. The maximum relative electron dose was 1.07 in the presence of tooth including amalgam for 14 MeV electron beam. When 100.00 cGy was prescribed for the reference point, the maximum absolute electron dose was 105.10 cGy in the presence of amalgam for 12 MeV electron beam and the maximum absolute photon contamination dose was 376.67 μGy for tooth in 14 MeV electron beam. The change in electron dose distribution should be considered in treatment planning, when teeth are irradiated in electron beam radiotherapy. If treatment planning can be performed in such a way that the teeth are excluded from primary irradiation, the potential errors in dose delivery to the tumour and normal tissues can be avoided.

  16. STRATEGIES FOR INCREASING PRODUCTIVITY IN PRODUCTION SYSTEMS

    Directory of Open Access Journals (Sweden)

    Diego Pacheco

    2014-05-01

    Full Text Available The main objective of this article is to point a set of practical strategies that can be adopted to increase the capacity of constraints resources on production systems, when the constraint is inside the factory and not is in the market. To serve this purpose will be presented strategies based on best practices of the Theory of Constraints, Lean Manufacturing and Total Productive Maintenance. This article also presents the mains tools for the deployment of these methodologies. The survey results have provided an objective set of practical strategy that can be used to increase the capacity and productivity of production systems according to the needs of each manufacturing system.

  17. PDT (Product Data Technology), Production and Society

    DEFF Research Database (Denmark)

    Vesterager, Johan

    1997-01-01

    Information and communication technology (ICT) constitute a genuine technical revolution by enabling a dynamic and flexible support or automation of knowledge and information work. Bearing in mind that products are frozen knowledge, ICT as known will change the way we produce products dramatically....... The use of ICT in engineering of products constitutes product data technology (PDT).This paper presents a a basic platform for an understanding the ongoing revolution with focus on the PDT-area taking outset in the fundamental elements of knowledge and information work: creation, transformation...

  18. Animal Production Research Advances

    African Journals Online (AJOL)

    Animal Production Research Advances is a peer-review journal established expressly to promote the production of all animal species utilized as food. The journal has an international scope and is intended for professionals in animal production and related sciences. We solicit contributions from animal production and ...

  19. Intelligent products : A survey

    NARCIS (Netherlands)

    Meyer, G.G.; Främling, K.; Holmström, J.

    This paper presents an overview of the field of Intelligent Products. As Intelligent Products have many facets, this paper is mainly focused on the concept behind Intelligent Products, the technical foundations, and the achievable practical goals of Intelligent Products. A novel classification of

  20. Making Product Customization Profitable

    DEFF Research Database (Denmark)

    Mortensen, Niels Henrik; Hvam, Lars; Haug, Anders

    2010-01-01

    The main result presented in this paper is the Framework for Product Family Master Plan. This framework supports the identification of a product architecture for companies that customize products and services. The framework has five coherent aspects, the market, product assortment, supply...