Sample records for abrasion tests

  1. Abrasion test of flexible protective materials on hydraulic structures

    Xin WANG


    Full Text Available In this study, several kinds of flexible protective materials sprayed with polyurea elastomers (hereinafter referred to as polyurea elastomer protective material were adopted to meet the abrasion resistance requirement of hydraulic structures, and their abrasion resistances against the water flow with suspended load or bed load were studied systematically through tests. Natural basalt stones were adopted as the abrasive for simulation of the abrasion effect of the water flow with bed load, and test results indicate that the basalt stone is suitable for use in the abrasion resistance test of the flexible protective material. The wear process of the polyurea elastomer protective material is stable, and the wear loss is linear with the time of abrasion. If the wear thickness is regarded as the abrasion resistance evaluation factor, the abrasion resistance of the 351 pure polyurea is about twice those of pure polyurea with a high level of hardness and aliphatic polyurea, and over five times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with suspended load. It is also about 50 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load. Overall, the abrasion resistance of pure polyurea presented a decreasing trend with increasing hardness. Pure polyurea with a Shore hardness of D30 has the best abrasion resistance, which is 60 to 70 times that of high-performance abrasion-resistant concrete under the abrasion of the water flow with bed load, and has been recommended, among the five kinds of pure polyurea materials with different hardness, in anti-abrasion protection of hydraulic structures.

  2. Testing of Commercial Cutting Heads for Abrasive Water Jet Technology

    Klich, J. (Jiří); Hlaváček, P.; M. Zeleňák; Sitek, L. (Libor); Foldyna, J. (Josef)


    Five different cutting heads designed for cutting by high-speed abrasive water jet technology were tested from cutting ability point of view. Straight kerfs were cut in several metal materials by abrasive water jet. Material removal volume was determined as a measure of performance of specific cutting head. Quality of cutting surface was observed, too. Results are compared and discussed.

  3. New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

    Macias, F. J.; Dahl, F.; Bruland, A.


    The tunnel boring machine (TBM) method has become widely used and is currently an important presence within the tunnelling industry. Large investments and high geological risk are involved using TBMs, and disc cutter consumption has a great influence on performance and cost, especially in hard rock conditions. Furthermore, reliable cutter life assessments facilitate the control of risk as well as avoiding delays and budget overruns. Since abrasive wear is the most common process affecting cutter consumption, good laboratory tests for rock abrasivity assessments are needed. A new abrasivity test method by rolling disc named Rolling Indentation Abrasion Test (RIAT) has been developed. The goal of the new test design and procedure is to reproduce wear behaviour on hard rock tunnel boring in a more realistic way than the traditionally used methods. Wear by rolling contact on intact rock samples is introduced and several rock types, covering a wide rock abrasiveness range, have been tested by RIAT. The RIAT procedure indicates a great ability of the testing method to assess abrasive wear on rolling discs. In addition and to evaluate the newly developed RIAT test method, a comprehensive laboratory testing programme including the most commonly used abrasivity test methods and the mineral composition were carried out. Relationships between the achieved results from conventional testing and RIAT results have been analysed.

  4. A review of micro-scale abrasion testing

    Gant, A J; Gee, M G [Electronics and Modelling Group, Division of Industry and Innovation, Module 9, Space G9-A5, Queens Road, Teddington, Middlesex, TW11 0LW (United Kingdom)


    Micro-scale abrasion (commonly referred to as 'ball cratering') is a small-scale tribological test method which can be operated on a desktop. It offers the possibility of providing a quick, cheap, localized abrasion test that can be used with small samples. In principle its operation is simple, but in practice there are issues with wear scar measurement, wear mode and its applicability to a wide variety of monolithic materials and coatings. (topical review)

  5. Standard test method for jaw crusher gouging abrasion test

    American Society for Testing and Materials. Philadelphia


    1.1 This test method covers a laboratory procedure to determine the relative gouging abrasion resistance of materials. Materials homogeneous in structure and properties are the most appropriate test materials; however, surface-treated and composite materials can also be tested. The test involves a small laboratory jaw crusher that crushes presized hard rock materials, such as a hard morainal gravel, or some other crushable substance. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (See 8.1 on Safety Precautions.)

  6. Review of Artificial Abrasion Test Methods for PV Module Technology

    Miller, David C. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Muller, Matt T. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Simpson, Lin J. [National Renewable Energy Lab. (NREL), Golden, CO (United States)


    This review is intended to identify the method or methods--and the basic details of those methods--that might be used to develop an artificial abrasion test. Methods used in the PV literature were compared with their closest implementation in existing standards. Also, meetings of the International PV Quality Assurance Task Force Task Group 12-3 (TG12-3, which is concerned with coated glass) were used to identify established test methods. Feedback from the group, which included many of the authors from the PV literature, included insights not explored within the literature itself. The combined experience and examples from the literature are intended to provide an assessment of the present industry practices and an informed path forward. Recommendations toward artificial abrasion test methods are then identified based on the experiences in the literature and feedback from the PV community. The review here is strictly focused on abrasion. Assessment methods, including optical performance (e.g., transmittance or reflectance), surface energy, and verification of chemical composition were not examined. Methods of artificially soiling PV modules or other specimens were not examined. The weathering of artificial or naturally soiled specimens (which may ultimately include combined temperature and humidity, thermal cycling and ultraviolet light) were also not examined. A sense of the purpose or application of an abrasion test method within the PV industry should, however, be evident from the literature.

  7. Abrasion Properties of Steel Fiber Reinforced Silica Fume Concrete According to Los Angeles and Water Abrasion Tests

    Tsan-Ching CHENG


    Full Text Available The current study mainly investigated the influence of different tests on the abrasion resistance of concrete mixed with steel fibers and silica fume. The abrasion resistance was assessed at 28, 56 and 91 days on concretes with water-binder ratios of 0.35 and 0.55 where in some mixes silica fume was substituted by 5 % of cement by weight. Steel fibers of 0.5 % and 1.0 % of concrete volume were also added into the test concrete by replacement of coarse and fine aggregates. The results showed that concrete with higher compressive strength in Los Angeles abrasion tests also had better abrasion resistance. The inclusion of steel fibers into test concrete with a water-binder ratio of 0.35 resulted in a significant increase in compressive strength. This concrete also displayed better abrasion resistance and splitting tensile strength than reference concrete; in the test sample with a water-binder ratio of 0.55, the added steel fibers was unable to effectively produce cementation with the concrete. The inclusion of silica fume improved the abrasion resistance of concretes. In water abrasion testing, the abrasion resistance of concrete containing steel fiber was worse than that of concrete without steel fibers. In the water abrasion testing, the surface of steel fiber reinforced concrete was eroded by water and steel balls, and the impact caused the steel fibers to separate from the concrete and led to higher wear loss. DOI:

  8. Abrasion Testing of Critical Components of Hydrokinetic Devices

    Worthington, Monty [ORPC Alaska; Ali, Muhammad [Ohio University; Ravens, Tom [University of Alaska Anchorage


    The objective of the Abrasion Testing of Critical Components of Hydrokinetic Devices (Project) was to test critical components of hydrokinetic devices in waters with high levels of suspended sediment – information that is widely applicable to the hydrokinetic industry. Tidal and river sites in Alaska typically have high suspended sediment concentrations. High suspended sediment also occurs in major rivers and estuaries throughout the world and throughout high latitude locations where glacial inputs introduce silt into water bodies. In assessing the vulnerability of technology components to sediment induced abrasion, one of the greatest concerns is the impact that the sediment may have on device components such as bearings and seals, failures of which could lead to both efficiency loss and catastrophic system failures.

  9. Abrasion Properties of Steel Fiber Reinforced Silica Fume Concrete According to Los Angeles and Water Abrasion Tests

    Tsan-Ching CHENG; Cheng, An; Ran HUANG; Lin, Wei-Ting


    The current study mainly investigated the influence of different tests on the abrasion resistance of concrete mixed with steel fibers and silica fume. The abrasion resistance was assessed at 28, 56 and 91 days on concretes with water-binder ratios of 0.35 and 0.55 where in some mixes silica fume was substituted by 5 % of cement by weight. Steel fibers of 0.5 % and 1.0 % of concrete volume were also added into the test concrete by replacement of coarse and fine aggregates. The results showed t...

  10. Standard Test Method for Abrasive Wear Resistance of Cemented

    American Society for Testing and Materials. Philadelphia


    1.1 This test method covers the determination of abrasive wear resistance of cemented carbides. 1.2 The values stated in inch-pound units are to be regarded as the standard. The SI equivalents of inch-pound units are in parentheses and may be approximate. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.


    Ronaldo Câmara Cozza


    Full Text Available The micro-abrasive wear tests by rotating ball (crater wear have played an important role in abrasive wear researches. In this type of test, the contact between a specimen and a ball on rotating motion and abrasive particles supplied between these two elements, results in a crater on the specimen, based on which the abrasive wear behaviour is analysed. The purpose of this work is to study results the reprodutibility and the silicon carbide (SiC abrasive particles fragmentation during micro-abrasive wear tests. Tests were conducted with carburized AISI 1010 steel balls and high speed steel specimens, “with” and “without” titanium nitride (TiN coatings. The abrasive slurry was prepared with black silicon carbide (average particle size of 5 µm and distilled water. Grooving abrasion is related with lower reprodutibility results. For the test conditions of this work, no abrasive particles fragmentation was observed, independently of the sliding distance, what is justified, among others factors, by the low normal force applied.

  12. 16 CFR Figure 8 to Part 1512 - Reflectorized Bicycle Wheel Rim Abrasion Test Device


    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Reflectorized Bicycle Wheel Rim Abrasion... HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Fig. 8 Figure 8 to Part 1512—Reflectorized Bicycle Wheel Rim Abrasion Test Device EC03OC91.074...

  13. A new method to test rock abrasiveness based on physico-mechanical and structural properties of rocks

    V.N. Oparin; A.S. Tanaino


    abstract A new method to test rock abrasiveness is proposed based upon the dependence of rock abrasiveness on their structural and physico-mechanical properties. The article describes the procedure of presentation of properties that govern rock abrasiveness on a canonical scale by dimensionless components, and the integrated estimation of the properties by a generalized index. The obtained results are compared with the known classifications of rock abrasiveness.

  14. Ice Abrasion and Bond Testing of Repair Mortars and High Performance Concrete

    Kirkhaug, Joakim Rydningen


    The purpose of this thesis has been to investigate ice abrasion properties for three different repair mortars, and evaluate their behavior and properties in relation to a typical B60 offshore concrete and a B70 concrete. Bond strength to a B60 concrete has been tested for all mortars. To increase understanding and knowledge in the field of research, a literature study was made. Roughness parameters, bond strength properties and parameters affecting ice abrasion resistance were reviewed. Testi...

  15. Micro-scale Abrasion and Medium Load Multiple Scratch Tests of PVD Coatings.

    S.Poulat; H.Sun; D.GTeer


    Micro-scale abrasion testing is widely used to determine the abrasion resistance of thin film coatings; it is a simple technique that can easily be used as part of a quality control procedure, but it has got the disadvantage of not allowing an easy study of the wear mechanisms involved: it is difficult to estimate the load applied on each abrasive particles in the contact between the loaded ball and the specimen. The possibility of using progressive loading scratch testing, a method widely used to assess the adhesion of thin film coatings, to model the abrasive wear of coatings has been studied in the past; the use of multiple scratch tests to study the wear mechanisms corresponding to a single abrasion scratch event has also been studied in the case of bulk materials (ceramics and hard metals). Two coatings, deposited by Closed Field Unbalanced Magnetron Sputter Ion Plating (CFUBMSIP) on ASP23 powder metallurgy steel substrate are chosen to be representative of the use of protective coatings in industry: titanium nitride, which is widely used to prevent tool wear, and TCL Graphit-iCTM, which is widely used as a wear resistant solid lubricant coating. The two coatings are first characterised by using a standard quality control procedure: their thickness is determined by the cap grinding method, their adhesion by progressive loading scratch. Then micro-scale abrasion tests performed with a slurry at a concentration which promotes grooving wear, and medium load multiple scratch tests performed with diamond indenters are completed; the results of these tests are analysed and compared to determine if there is any correlation between the two sets of results; the multiple scratch tests wear tracks are also observed to determine the wear mechanisms involved.

  16. Abrasion Testing of Candidate Outer Layer Fabrics for Lunar EVA Space Suits

    Mitchell, Kathryn C.


    During the Apollo program, the space suit outer layer fabrics were badly abraded after just a few Extravehicular Activities (EVAs). For example, the Apollo 12 commander reported abrasive wear on the boots, which penetrated the outer layer fabric into the thermal protection layers after less than eight hours of surface operations. Current plans for the Constellation Space Suit Element require the space suits to support hundreds of hours of EVA on the Lunar surface, creating a challenge for space suit designers to utilize materials advances made over the last forty years and improve upon the space suit fabrics used in the Apollo program. A test methodology has been developed by the NASA Johnson Space Center Crew and Thermal Systems Division for establishing comparative abrasion wear characteristics between various candidate space suit outer layer fabrics. The abrasion test method incorporates a large rotary drum tumbler with rocks and loose lunar simulant material to induce abrasion in fabric test cylinder elements, representative of what might occur during long term planetary surface EVAs. Preliminary materials screening activities were conducted to determine the degree of wear on representative space suit outer layer materials and the corresponding dust permeation encountered between subsequent sub -layers of thermal protective materials when exposed to a simulated worst case eight hour EVA. The test method was used to provide a preliminary evaluation of four candidate outer layer fabrics for future planetary surface space suit applications. This Paper provides a review of previous abrasion studies on space suit fabrics, details the methodologies used for abrasion testing in this particular study, and shares the results and conclusions of the testing.

  17. Abrasion and erosion testing of materials used in power production from coal

    Tylczak, Joseph H.; Adler, Thomas A.; Rawers, James C.


    The Albany Research Center (ARC) has a long history of studying abrasive wear, related to mineral testing, handling, and processing. The center has also been instrumental in the design and development of wear test procedures and equipment. Research capabilities at ARC include Pin-on-Drum, Pin-on-Disk, and Dry Sand/Rubber Wheel abrasion tests, Jaw Crusher gouging test, Ball-on-Ball Impact test, and Jet erosion tests. Abrasive and erosive wear studies have been used to develop both new alloys and improved heat treatments of commercial alloys. As part of ARC’s newest iteration on wear testing to evaluate materials for use in new and existing pulverized coal combustion and gasifier power systems, the ARC has designed and constructed a new High Temperature Hostile Atmosphere Erosion Wear Test (HAET). This new piece of test apparatus is designed for erosive particle velocities of 10-40 m/sec and temperatures from room temperature (23°C) to 800+°C, with special control over the gas atmosphere. A variable speed whirling arm design is used to vary the impact energy of the gravity fed erosive particles. The specimens are mounted at the edge of a disk and allow a full range of impingement angles to be selected. An electric furnace heats the specimens in an enclosed retort to the selected temperature. Tests include both oxidizing conditions and reducing conditions. A range of gases, including CO, CO2, CH4, H2, H2S, HCl, N2, O2, and SO2 can be mixed and delivered to the retort. During the erosion testing a stream of abrasive powder is delivered in front of the specimens. This apparatus is designed to use low abrasive fluxes, which simulate real operating conditions in commercial power plants. Currently ~270 μm SiO2 particles are being used to simulate the abrasive impurities typically found in coal. Since operators are always striving for longer lifetimes and higher operating temperatures, this apparatus can help elucidate mechanisms of wastage and identify superior

  18. Abrasive Wear Resistance of the Iron- and WC-based Hardfaced Coatings Evaluated with Scratch Test Method

    A. Vencl


    Full Text Available Abrasive wear is one of the most common types of wear, which makesabrasive wear resistance very important in many industries. Thehard facing is considered as useful and economical way to improve theperformance of components submitted to severe abrasive wear conditions, with wide range of applicable filler materials. The abrasive wear resistance of the three different hardfaced coatings (two iron‐based and one WC‐based, which were intended to be used for reparation of the impact plates of the ventilation mill, was investigated and compared. Abrasive wear tests were carried‐out by using the scratch tester under the dry conditions. Three normal loads of 10, 50 and 100 N and the constant sliding speed of 4 mm/s were used. Scratch test was chosen as a relatively easy and quick test method. Wear mechanism analysis showed significant influence of the hardfaced coatings structure, which, along with hardness, has determined coatings abrasive wear resistance.

  19. Abrasive Wear Resistance of Tool Steels Evaluated by the Pin-on-Disc Testing

    Bressan, José Divo; Schopf, Roberto Alexandre


    Present work examines tool steels abrasion wear resistance and the abrasion mechanisms which are one main contributor to failure of tooling in metal forming industry. Tooling used in cutting and metal forming processes without lubrication fails due to this type of wear. In the workshop and engineering practice, it is common to relate wear resistance as function of material hardness only. However, there are others parameters which influences wear such as: fracture toughness, type of crystalline structure and the occurrence of hard precipitate in the metallic matrix and also its nature. In the present investigation, the wear mechanisms acting in tool steels were analyzed and, by normalized tests, wear resistance performance of nine different types of tool steels were evaluated by pin-on-disc testing. Conventional tool steels commonly used in tooling such as AISI H13 and AISI A2 were compared in relation to tool steels fabricated by sintering process such as Crucible CPM 3V, CPM 9V and M4 steels. Friction and wear testing were carried out in a pin-on-disc automated equipment which pin was tool steel and the counter-face was a abrasive disc of silicon carbide. Normal load of 5 N, sliding velocity of 0.45 m/s, total sliding distance of 3000 m and room temperature were employed. The wear rate was calculated by the Archard's equation and from the plotted graphs of pin cumulated volume loss versus sliding distance. Specimens were appropriately heat treated by quenching and three tempering cycles. Percentage of alloying elements, metallographic analyses of microstructure and Vickers microhardness of specimens were performed, analyzed and correlated with wear rate. The work is concluded by the presentation of a rank of tool steel wear rate, comparing the different tool steel abrasion wear resistance: the best tool steel wear resistance evaluated was the Crucible CPM 9V steel.

  20. A new methodology for hydro-abrasive erosion tests simulating penstock erosive flow

    Aumelas, V.; Maj, G.; Le Calvé, P.; Smith, M.; Gambiez, B.; Mourrat, X.


    Hydro-abrasive resistance is an important property requirement for hydroelectric power plant penstock coating systems used by EDF. The selection of durable coating systems requires an experimental characterization of coating performance. This can be achieved by performing accelerated and representative laboratory tests. In case of severe erosion induced by a penstock flow, there is no suitable method or standard representative of real erosive flow conditions. The presented study aims at developing a new methodology and an associated laboratory experimental device. The objective of the laboratory apparatus is to subject coated test specimens to wear conditions similar to the ones generated at the penstock lower generatrix in actual flow conditions. Thirteen preselected coating solutions were first been tested during a 45 hours erosion test. A ranking of the thirteen coating solutions was then determined after characterisation. To complete this first evaluation and to determine the wear kinetic of the four best coating solutions, additional erosion tests were conducted with a longer duration of 216 hours. A comparison of this new method with standardized tests and with real service operating flow conditions is also discussed. To complete the final ranking based on hydro-abrasive erosion tests, some trial tests were carried out on penstock samples to check the application method of selected coating systems. The paper gives some perspectives related to erosion test methodologies for materials and coating solutions for hydraulic applications. The developed test method can also be applied in other fields.

  1. Standardization of a Volumetric Displacement Measurement for Two-Body Abrasion Scratch Test Data Analysis

    Street, K. W. Jr.; Kobrick, R. L.; Klaus, D. M.


    A limitation has been identified in the existing test standards used for making controlled, two-body abrasion scratch measurements based solely on the width of the resultant score on the surface of the material. A new, more robust method is proposed for analyzing a surface scratch that takes into account the full three-dimensional profile of the displaced material. To accomplish this, a set of four volume- displacement metrics was systematically defined by normalizing the overall surface profile to denote statistically the area of relevance, termed the Zone of Interaction. From this baseline, depth of the trough and height of the plowed material are factored into the overall deformation assessment. Proof-of-concept data were collected and analyzed to demonstrate the performance of this proposed methodology. This technique takes advantage of advanced imaging capabilities that allow resolution of the scratched surface to be quantified in greater detail than was previously achievable. When reviewing existing data analysis techniques for conducting two-body abrasive scratch tests, it was found that the ASTM International Standard G 171 specified a generic metric based only on visually determined scratch width as a way to compare abraded materials. A limitation to this method was identified in that the scratch width is based on optical surface measurements, manually defined by approximating the boundaries, but does not consider the three-dimensional volume of material that was displaced. With large, potentially irregular deformations occurring on softer materials, it becomes unclear where to systematically determine the scratch width. Specifically, surface scratches on different samples may look the same from a top view, resulting in an identical scratch width measurement, but may vary in actual penetration depth and/or plowing deformation. Therefore, two different scratch profiles would be measured as having identical abrasion properties, although they differ

  2. Standard test method for abrasiveness of ink-impregnated fabric printer ribbons and other web materials

    American Society for Testing and Materials. Philadelphia


    1.1 This test method covers the determination of the abrasiveness of ink-impregnated fabric printer ribbons and other web materials by means of a sliding wear test. 1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  3. Methods of data analysis for the micro-scale abrasion test on coated substrates

    Kusano, Y.; Acker, K. Van; Hutchings, I.M.


    The micro-scale abrasive wear test is attractive for coated substrates because it is simple, only small samples are required, and the specific wear rates for both coating and substrate kappa(c) and kappa(s) can be determined simultaneously. This paper reviews and critically discusses the methods...... and the coating thickness. In general the errors in kappa(c) and kappa(s) are determined by the ratio of the specific wear rates kappa(c)/kappa(s), the non-dimensional parameter a(2)/Rt (where a is the inner crater diameter, R is the ball radius and t is the coating thickness), and the relative measurement errors...... another method, termed the KVH plot, is shown to be somewhat more consistently accurate. Detailed guidelines are proposed for analysing the data by this method. (C) 2003 Elsevier B.V. All rights reserved....

  4. Abrasion Testing of Products Containing Nanomaterials, SOP-R-2: Scientific Operating Procedure Series: Release (R)


    chamber with controlled, HEPA-filtered air inflow connected to an instrument bank (CPC, FMPS) and in-line filters to collect abrasion-generated particles...Guiot, G. Uzu, J. Chatenet and F. Tardif. 2011. Characterization of abrasion-induced nanoparticle release from paints into liquids and air. Journal of

  5. Mathematical model for abrasive suspension jet cutting based on orthogonal test design

    HU Gui-hua; ZHU Wen-hua; CAI Hong-xia; XU Chong; BAI Yu-jie; CHENG Jun; YUAN Jin; YU Tao


    This paper describes the application of orthogonal test design coupled with non-linear regression analysis to optimize abrasive suspension jet (AS J) cutting process and construct its cutting model. Orthogonal test design is applied to cutting stainless steel. Through range analysis on experiment results, the optimal process conditions for the cutting depth and the kerf ratio of the bottom width to the top width can be determined. In 'addition, the analysis of ranges and variances are all employed to identify various factors: traverse rate, working pressure, nozzle diameter, standoff distance which denote the importance order of the cutting parameters affecting cutting depth and the kerf ratio of the bottom width to the top width. Furthermore, non-linear regression analysis is used to establish the mathematical models of the cutting parameters based on the cutting depth and the kerf ratio. Finally, the verification experiments of cutting parameters' effect on cutting performance, which show that optimized cutting parameters and cutting model can significantly improve the prediction of the cutting ability and quality of ASJ.

  6. Measurement of the Resistance of Treated Metal Foils to Scrubbing Abrasion Using a Modified Reciprocating Wear Test

    Qu, Jun [ORNL; Blau, Peter Julian [ORNL; Sikka, Vinod K [ORNL


    A reciprocating wear test method has been developed to evaluate the resistance of metal foils to scrubbing abrasion. Development included the definition of a quantitative measure of the scrubbing resistance. In order to test the ability of the new method to differentiate between surface treatments, four versions of Type 316 stainless steel foils were tested: annealed (A-NT), cold-worked (C-NT), annealed plus a case-hardened (A-T), and cold-worked plus case-hardened (C-T). Measurements were made of their scrubbing resistance using commercial kitchen scrub pads as the counterface material. Results showed that the case-hardening process significantly increased the scrubbing resistance both under dry conditions and with cleaning solutions to lubricate the contact. While this linearly-reciprocating method does not simulate the circular, overlapping motion commonly occurring in service, results indicated that the new test method could sufficiently discriminate levels of two-body abrasion behavior, and therefore can be useful for studying the effects of surface treatments on abrasion resistance.

  7. The influence of linear velocity on the wear behaviour of thermal sprayed coatings under dynamic abrasion test conditions

    Kennedy, D.M. [Carlow RTC (Ireland); Hashmi, M.S.J. [Dublin City Univ. (Ireland)


    Surface coatings applied by a high-velocity oxy fuel (HVOF) thermal spray process were subjected to a newly developed dynamic abrasion test. The test consists of combined impact and abrasion. Impact of samples with a round nose stylus was conducted at two specified linear velocities. The wear rates corresponding with the linear velocities were recorded and compared for a number of test cycles. Different substrate materials were used for the test and a number of coating thicknesses were examined. Uncoated samples were subjected to identical tests. Unlike many wear test processes currently in use, the wear test developed and used here is severe and fast acting, making it suitable for thick coatings and situations involving combined wear. The results of the wear tests show the effects of the linear velocity prior to impact on the surfaces in term of material loss and crater depth caused by dynamic wear testing. The influence of rebound following impact, combined with the linear velocity of the reciprocating stylus, has a major effect on the wear rates of the samples tested. (orig.) 11 refs.

  8. Development and Testing of Abrasion Resistant Hard Coats For Polymer Film Reflectors: Preprint

    Jorgensen, G.; Gee, R.; DiGrazia, M.


    Reflective polymer film technology can significantly reduce the cost of solar reflectors and installed Concentrated Solar Power (CSP) plants by both reduced material cost and lower weight. One challenge of polymer reflectors in the CSP environment pertains to contact cleaning methods typically used with glass mirrors. Such contact cleaning methods can scratch the surface of polymer reflectors and thereby reduce specular reflectance. ReflecTech, Inc. (a subsidiary of SkyFuel, Inc.) and the National Renewable Energy Laboratory (NREL) initiated a cooperative research and development agreement (CRADA) to devise and develop an abrasion resistant coating (ARC) suitable for deposition onto polymer based mirror film. A number of candidate ARC products were identified as candidate formulations. Industrial collaborators prepared samples having their ARCs deposited onto ReflecTech Mirror Film pre-laminated to aluminum sheet substrates. Samples were provided for evaluation and subjected to baseline (unweathered) and accelerated exposure conditions and subsequently characterized for abrasion resistance and adhesion. An advanced ARC product has been identified that exhibits outstanding initial abrasion resistance and adhesion to ReflecTech Mirror Film. These properties were also retained after exposure to the various accelerated stress conditions. This material has been successfully manufactured as a 1.5 m wide roll-to-roll construction in a production environment.

  9. Corneal Abrasions

    ... and lead to a serious condition called a corneal ulcer . That's why it's important to see a doctor to get a corneal abrasion checked out. What Causes a Corneal ... and land on your cornea, tears help to wash the particles away. Sometimes, ...

  10. Testing of Alternative Abrasives for Water-Jet Cutting at C Tank Farm

    Krogstad, Eirik J.


    Legacy waste from defense-related activities at the Hanford Site has predominantly been stored in underground tanks, some of which have leaked; others may be at risk to do so. The U.S. Department of Energy’s goal is to empty the tanks and transform their contents into more stable waste forms. To do so requires breaking up, and creating a slurry from, solid wastes in the bottoms of the tanks. A technology developed for this purpose is the Mobile Arm Retrieval System. This system is being used at some of the older single shell tanks at C tank farm. As originally planned, access ports for the Mobile Arm Retrieval System were to be cut using a high- pressure water-jet cutter. However, water alone was found to be insufficient to allow effective cutting of the steel-reinforced tank lids, especially when cutting the steel reinforcing bar (“rebar”). The abrasive added in cutting the hole in Tank C-107 was garnet, a complex natural aluminosilicate. The hardness of garnet (Mohs hardness ranging from H 6.5 to 7.5) exceeds that of solids currently in the tanks, and was regarded to be a threat to Hanford Waste Treatment and Immobilization Plant systems. Olivine, an iron-magnesium silicate that is nearly as hard as garnet (H 6.5 to 7), has been proposed as an alternative to garnet. Pacific Northwest National Laboratory proposed to test pyrite (FeS2), whose hardness is slightly less (H 6 to 6.5) for 1) cutting effectiveness, and 2) propensity to dissolve (or disintegrate by chemical reaction) in chemical conditions similar to those of tank waste solutions. Cutting experiments were conducted using an air abrader system and a National Institute of Standards and Technology Standard Reference Material (SRM 1767 Low Alloy Steel), which was used as a surrogate for rebar. The cutting efficacy of pyrite was compared with that of garnet and olivine in identical size fractions. Garnet was found to be most effective in removing steel from the target; olivine and pyrite were less

  11. Abrasion of ultrafine WC-Co by fine abrasive particles


    Abrasive wear of a series of WC-(5%-14%, mass fiaction)Co hardmetals was investigated employing coarse and fine SiC abrasive under two-body dry abrasion conditions with pin-on-disc and edge-on-disc test arrangements. Unexpectedly, it is found that submicron grades demonstrate substantially higher wear rates comparing with the coarse grades if fine abrasive is utilized in pin-on-disc tests. Such a behavior is attributed to changes in a ratio of abrasive size to size of hard phase as finer abrasive is used.The edge-on-disc test demonstrates that edge wear may be described in two stages with the highest wear rates at the beginning stage.This behavior is associated with a transition of wear mechanisms as edge is wider due to wear. Compared with the ultrafine grades of the same Co content, the coarse grades demonstrate higher wear rates at the beginning, but lower wear rates at the final stage. Wear rates and mechanisms observed at final stage correlate well to the results observed for pin-on-disc tests employing fine abrasive.

  12. Rocks with Asbestos: Risk Evaluation by Means of an Abrasion Test

    Bellopede Rossana


    Full Text Available Naturally occurring asbestos and asbestiform minerals can be found in metamorphic rocks and in the soil of the alluvial plains. Problem statement: The definition of the "free-asbestos rock" and the limit to consider a rock or a soil safe is still a controversial issue. American and European laws did not present any method to define the hazard of the green stones, instead Italian law, in Ministerial Decree1996, established a limit value obtaoined by the determination of the Release Index. In order to detect an asbestos concentration in the rocks, a reliable analytic methodology has been necessary. Approach: An abrasion trial, using the mechanism action of a rotary cylinder, and a Phase Contrast Optical Microscopy (PCOM method to analyze the powder obtained from the mill, had been used. To simplify PCOM analysis, the sample, recovered from the mill, was selected in particle size classes: large, medium and small. Each class was separated by means of sedimentation in fibrous and granular fractions. Results: The separation of asbestos in large and medium classes was quite good and the fibers had been weighed. For the small class the transformation of visible data into numerical data was complex, but the results had been reliable. Conclusion/Recommendations: The suggested method, although semi-quantitative, could be useful to solve the difficult problem of the analysis of the asbestos content in the rocks or soils. The division into granular classes allowed a more representative sample to be analyzed and better quality slides to be prepared. From the results obtained, the analysis of the small classes by means of PCOM was a critical point: The use of the SEM method can improve it.

  13. The increase in cobalt release in metal-on-polyethylene hip bearings in tests with third body abrasives.

    de Villiers, Danielle; Traynor, Alison; Collins, Simon N; Shelton, Julia C


    Hypersensitivity reactions in patients receiving metal-on-metal hip replacements have been attributed to corrosion products as observed by elevated cobalt and chromium ions in the blood. Although the majority of cases are reported in metal-on-metal, incidences of these reactions have been reported in the metal-on-polyethylene patient population. To date, no in vitro study has considered cobalt release for this bearing combination. This study considered four 28 mm and seven 52 mm diameter metal-on-polyethylene bearings tested following ISO standard hip simulator conditions as well as under established abrasive conditions. These tests showed measurable cobalt in all bearings under standard conditions. Cobalt release, as well as polyethylene wear, increased with diameter, increasing from 52 to 255 ppb. The introduction of bone cement particles into the articulation doubled polyethylene wear and cobalt release while alumina particles produced significant damage on the heads demonstrated by cobalt levels of 70,700 ppb and an increased polyethylene wear from a mean value of 9-160 mm(3)/mc. Cobalt release was indicative of head damage and correlated with polyethylene wear at the next gravimetric interval. The removal of third body particles resulted in continued elevated cobalt levels in the 52 mm diameter bearings tested with alumina compared to standard conditions but the bearings tested with bone cement particles returned to standard levels. The polyethylene wear in the bone cement tested bearings also recovered to standard levels, although the alumina tested bearings continued to wear at a higher rate of 475 mm(3)/mc. Cobalt release was shown to occur in metal-on-polyethylene bearings indicating damage to the metal head resulting in increased polyethylene wear. While large diameter metal-on-polyethylene bearings may provide an increased range of motion and a reduced dislocation risk, increased levels of cobalt are likely to be released and this needs to be fully

  14. Rubberized Concrete Durability Against Abrasion

    Md Noor Nurazuwa


    Full Text Available Durability performance of rubberized concrete against abrasion is presented in this paper. Surface depth loss was measured when abrasion load was constantly applied on concrete surface at each 500 interval rotation. Specimen with water-to cement ratio of 0.50 and 0.35 was prepared and tested at 28 days of curing age. In addition, 10% silica fume, SF was added to provide denser concrete and to understand its effectiveness against wear when added with crumb rubber. Results showed that crumb rubber shows good potential in providing abrasion resistance to concrete mix. However, in the case of rubberized concrete with silica fume, abrasion resistance was found to be slightly decreased with compressive strength more than 50N/mm2 due to the lack of low elastic modulus of CR particles to accommodate with denser cement matrix.

  15. Clasp retention and composites: an abrasion study.

    Davenport, J C; Hawamdeh, K; Harrington, E; Wilson, H J


    An in vitro test for screening the abrasion resistance and abrasivity of composite resins when used to provide tooth undercuts for removable partial denture clasps is described. In the present study nine composite resins were tested against wrought stainless steel round clasps. The results indicated that the abrasion of any of the composites tested was unlikely to cause a noticeable loss of retention in the clinical situation. However, there was marked abrasion of the clasps by two of the composites which would be likely to be clinically relevant.

  16. Abrasive Properties of Test and Training Site Soils: Relative Hardness of Fine Particle Fraction


    scales and mea- and examined for striations by incident light micro- surement techniques are reviewed by Sarkar (1980), scopy. Rabinowicz (1965...wear of cordage more likely approaches three- bor 1954, Howell et al. 1959, Rabinowicz 1965, body wear, as described by Rabinowicz (1965). Sarkar 1980...CONCLUSIONS Friction in Textiles. New York: Textile Book Publish- ers (Interscience). Soil specimens from several test and training Rabinowicz , E

  17. Sustainability of abrasive processes

    Aurich, J.C.; Linke, B.; Hauschild, Michael Zwicky


    This paper presents an overview of research on sustainability of abrasive processes. It incorporates results from a round robin study on ‘‘energy-efficiency of abrasive processes’’ which has been carried out within the scientific technical committee ‘‘abrasive processes’’ (STC G) of CIRP...

  18. The abrasion and impact-abrasion behavior of austempered ductile irons

    Hawk, Jeffrey A.; Dogan, Omer N.; Lerner, Y.S. (University of Northern Iowa)


    Austempering of ductile irons has led to a new class of irons, Austempered Ductile Irons (ADIs), with improved mechanical strength and fracture toughness lacking in gray cast irons. Laboratory wear tests have been used to evaluate the abrasive and impact-abrasive wear behavior of a suite of ADIs. The use of high-stress, two-body abrasion, low-stress, three-body abrasion, and impact-abrasion tests provides a clear picture of the abrasive wear behavior of the ADIs and the mechanisms of material removal. When combined with hardness measurements, fracture toughness and a knowledge of the microstructure of the ADIs, the overall performance can be assessed relative to more wear resistant materials such as martensitic steels and high-chromium white cast irons

  19. Restorative resins: abrasion vs. mechanical properties.

    Jørgensen, K D


    The purpose of the present work was to examine whether it is possible by simple and reliable laboratory tests to evaluate the abrasion by food of Class 1 restorative resins. The results point to the following main conclusions: for the smooth-surface resins, i.e. the micro-filled composite and the unfilled resins, the Wallace hardness test appears to be a valid parameter for abrasion; the greater the depth of penetration of the Vickers diamond of this apparatus, the more severe abrasion is to be expected. The mode of abrasion in this type of resin is scratching. Porosity in the resins strongly enhances the abrasion. For the rough-surface resins, i.e. the conventional composites, a dual effect of the filler particles was concluded. The filler particles on the one hand protect the matrix against abrasion, but cause, on the other hand, in time an increase of the surface roughness of the composite and thereby via increased friction an increase of the abrasion. Considerations on possible ways to improve the present-day restorative resins are presented. It is stressed that the results obtained refer only to abrasion of Class 1 fillings by food.

  20. Usage of abrasion-resistant materials in agriculture

    J Votava


    Full Text Available Agricultural soil-processing machines are subject to an extensive abrasive wear. This paper analyses technical materials and their fitness to exchangeable parts of plough bottoms, such as edge-tools and whole plough cutting edges. There were tested abrasion-resistant steels with different microstructures: austenite, martensite-bainite, and carbide. Steel with the pearlite-ferrite structure was used as an etalon. Abrasion resistance tests were processed in compliance with the norm CSN 01 5084, which is a test of abrasion wear on abrasive cloth.

  1. The measurement of abrasive particles velocities in the process of abrasive water jet generation

    Zeleňák, Michal; Foldyna, Josef; Říha, Zdeněk


    An optimization of the design of the abrasive cutting head using the numerical simulation requires gathering as much information about processes occurring in the cutting head as possible. Detailed knowledge of velocities of abrasive particles in the process of abrasive water jet generation is vital for the verification of the numerical model. A method of measurement of abrasive particles at the exit of focusing tube using the FPIV technique was proposed and preliminary tests are described in the paper. Results of analysis of measured velocity fields are presented in the paper.

  2. The effect of bleaching on toothbrush abrasion of resin composites

    Hila Hajizadeh


    Full Text Available Aim: This experimental study was designed to focus on the effects of bleaching on toothbrush abrasion in three types of composites with different filler size. Materials and Methods: Forty eight disks were prepared from three types of composite and divided into 6 groups. In the first three groups the abrasion test was done. The remaining groups were bleached and the abrasion test was performed. The weight of the samples before and after abrasion was measured. Statistical analysis was done with one-way ANOVA and Duncan test. Results: There was a significant difference in abrasion of composites with different filler size (P < 0.05. The most amount of abrasion was observed in Z100 after being bleached. An increase in abrasion was noticed in all three types of tested composite after bleaching. Conclusion: According to the findings, it is suggested to use a nano filled resin composite for restoration if the bleaching treatment is required.

  3. Ultrasonic magnetic abrasive finishing

    LU Ya-ping; MA Ji; ZHANG Jun-qiang; WANG Long-shan


    Put forward a new kind of polishing method, ultrasonic magnetic abrasive finishing (UMAF), and studied its mechanism of improving polishing efficiency. By analyzing all kind of forces acting on single abrasive particle in the polishing process and calculating the size of the composition of forces, get the conclusion that UMAF will enhance the efficiency of the normal magnetic abrasive finishing(MAF) due to the ultrasonic vibration increases the cutting force and depth. At last the idea of designing the UMAF system based on numerical control milling machine is put forward which is convenient to setup and will accelerate the practical application of MAF.

  4. Third abrasive wear mode: is it possible?

    Ronaldo Câmara Cozza


    Full Text Available The objective of this paper is to propose an initial discussion on the characterization of a third abrasive wear mode. The results obtained in a previous work [1] under different test conditions revealed the occurrence of the superposition of the “rolling” and “grooving” abrasive wear modes. This phenomenon was denoted “micro-rolling abrasion” due to the observation that “rolling abrasion” was found to act on “grooving abrasion”.

  5. Investigations on the trajectories of magnetic abrasive grains in magnetic induction-free abrasive wire sawing

    Zhang, Wei; Yao, Chunyan; Tang, Chen; Qiu, Tengwei; Xu, Xuefeng


    This study presents a novel method of magnetic induction-free abrasive wire sawing. The ferromagnetic wire is magnetized in a uniform magnetic field, forming a high-gradient magnetic field that separates into paramagnetic and diamagnetic regions. Paramagnetic abrasive grains are attracted to the paramagnetic region and adhere to the wire surface but are repelled from the diamagnetic region. The trajectory of the magnetic abrasive grains is analyzed in a mathematical model and in COMSOL Multiphysics simulations. The results are verified by test investigations on the motions and adsorption of the magnetic abrasive grains using a dynamic microscope system. The detailed grain trajectories are investigated in a numerical model. Because it actively transports grains toward the wire (where they can be transported to the sawing channel), our proposed method achieves more efficient wire sawing performance than traditional free abrasive wire sawing. Such efficient performance is highly sought in silicon wafering technologies, which are commonly used in the solar and semiconductor industries.

  6. Contact air abrasion.

    Porth, R


    The advantages of contact air abrasion techniques are readily apparent. The first, of course, is the greatly increased ease of use. Working with contact also tends to speed the learning curve by giving the process a more natural dental feel. In addition, as one becomes familiar with working with a dust stream, the potential for misdirecting the air flow is decreased. The future use of air abrasion for deep decay removal will make this the treatment of choice for the next millennium.

  7. The Abrasion-resistance Investigation of Rubberized Concrete

    KANG Jingfu; ZHANG Bo; LI Guangyu


    The abrasion resistance properties of rubberized concrete were comparatively studied by taking silica fume and crumb tire rubber as the additives.The abrasion tests were conducted in accordance with the Chinese standard test method DL/T 5150-2001,two recommended test methods:under water method and ring method,were used.The crumb tire rubbers with the sieve size of 8-mesh and 16-mesh were incorporated into the concrete by replacing same volume of sand and as an additive.The abrasion resistance of concrete was evaluated according to the abrasion resistance strength and the mass loss.Test results show that the addition of silica fume enhanced both compressive strength and abrasion resistance of concrete,and the addition of crumb rubber reduced the compressive strength but increased notably the abrasion resistance of the concrete.Silica fume concrete performed a better abrasion resistance than control concrete,and the rubberized concrete performed a much better abrasion resistance than silica fume concrete.The abrasion resistance of rubberized concrete increased with the increase of rubber content.

  8. Abrasion Resistant Refractory Materials GB/T 23294-2009

    Yu Lingyuan


    @@ 1 Scope This standard specifies the definition, classification, technical requirements, test methods, quality appraisal procedure, packing, marking, transportation, storage, and quality certificate of abrasion resistant refractory materials. This standard is applicable to abrasion resistant refractory materials for circulating fluidized bed boilers, daily waste incinerator, industrial waste incinerator, medical waste incinerator, ordinary solid waste incinerator, hazardous waste incinerator, etc.

  9. Sowing simulation tests of a pneumatic drill equipped with systems aimed at reducing the emission of abrasion dust from maize dressed seed.

    Biocca, Marcello; Conte, Elisa; Pulcini, Patrizio; Marinelli, Enzo; Pochi, Daniele


    The utilization of dressed seed for spring sowing is a widespread practice to control some pests with reduced doses of chemical products. However some insecticides employed in maize seed dressing, namely belonging to the neonicotinoid family and fipronil, have been claimed to play a role in the decline of honeybees (Apis mellifera L.). Pneumatic drills used in maize sowing are charged with contributing to the dispersion of the abrasion dust produced by dressed seeds, favoring the contamination of the honeybee habitat. Different devices similar to air deflectors have been introduced on pneumatic drills in order to reduce dust drift. During previous field tests carried out by the authors during recent years reduction of dust concentration both in the air and at soil surface has been shown as a consequence of their application. As field tests are affected by the variability of environmental parameters (namely wind speed and direction) the results are not always reliable, comparable and of a general validity. This paper refers to a sowing simulation test system in which pneumatic drills can be tested at a fixed point under controlled conditions of the main environmental parameters. In the test area, protected by external influences, artificial wind conditions are created by means of a fan. The drill, suitably placed in the test area, operates the seed distribution "sur place" by means of an electric engine connected to the drill's driving wheel. A 22.5 m long sampling area, leeward with respect to the drill position, has been identified. Along the sampling area a series of Petri dishes has been placed, with the aim of capturing the depositing dust and providing the concentration of the active ingredients (a.i.) at ground level. At the same time, three air samplers with PTFE diskette filters have been used for the detection of the a.i. The test system has been used for the test of a pneumatic drill, equipped with and without air deflectors, using maize seed dressed with

  10. Abrasive water jet cutting as a new procedure for cutting cancellous bone--in vitro testing in comparison with the oscillating saw.

    Schwieger, Karsten; Carrero, Volker; Rentzsch, Reemt; Becker, Axel; Bishop, Nick; Hille, Ekkehard; Louis, Hartmut; Morlock, Michael; Honl, Matthias


    The quality of bone cuts is assessed by the accuracy and biological potency of the cut surfaces. Conventional tools (such as saws and milling machines) can cause thermal damage to bone tissue. Water jet cutting is nonthermal; that is, it does not generate heat. This study investigates whether the abrasive jet cutting quality in cancellous bone with a biocompatible abrasive is sufficient for the implantation of endoprostheses or for osteotomies. Sixty porcine femoral condyles were cut with an abrasive water jet and with an oscillating saw. alpha-lactose-monohydrate was used as a biocompatible abrasive. Water pressure (pW = 35 and 70 MPa) and abrasive feed rate (m = 0.5, 1, and 2 g/s) were varied. As a measure of the quality of the cut surface the cutting gap angle (delta) and the surface roughness (Ra) were determined. The surface roughness was lowest for an abrasive feed rate of m = 2 g/s (jet direction: 39 +/- 16 microm, advance direction: 54 +/- 22 microm). However, this was still significantly higher than the surface roughness for the saw group (jet direction: 28 +/- 12 microm, advance direction: 36 +/- 19 microm) (p cutting gap angle was observed for a mass flow rate of m = 1 g/s (pW = 35 MPa: delta = 2.40 +/- 4.67 degrees ; pW = 70 MPa: delta = 4.13 +/- 4.65 degrees), which was greater than for m = 0.5 g/s (pW = 35 MPa: delta = 1.63 +/- 3.89 degrees ; pW = 70 MPa: delta = 0.36 +/- 1.70 degrees) and m = 2 g/s (pW =70 MPa: delta = 0.06 +/- 2.40 degrees). Abrasive water jets are suitable for cutting cancellous bone. The large variation of the cutting gap angle is, however, unfavorable, as the jet direction cannot be adjusted by a predefined value. If it is possible to improve the cutting quality by a further parameter optimization, the abrasive water jet may be the cutting technique of the future for robotic usage.

  11. Shore plartform abrasion in a para-periglacial environment, Galicia, northwestern Spain


    [EN] The Schmidt Rock Test Hammer was used to study the effect of abrasion on shore platforms in Galicia, northwestern Spain. On platforms where tidally-induced weathering (salt, wetting and drying, etc.) is dominant, rock strength is significantly lower than in areas where abrasion is, or has been active in the recent past. This suggests that abrasion removes weathered surface material, exposing the stronger, less weathered rock below. Abrasion downwearing, measured with a transverse micro-e...

  12. Abrasive wear behaviour of as cast and austempered ductile irons

    Baydogan, M.; Koekden, M.U.; Cimenoglu, H. [Istanbul Technical Univ., Dept. of Metallurgy and Materials Science Engineering Istanbul (Turkey)


    In this study, abrasive wear behaviour of as cast and austempered GGG 50 and GGG 80 quality ductile irons was investigated. In the as cast condition, GGG 50 and GGG 80 quality ductile irons were having ferritic and pearlitic matrix structures, respectively. Austempering at 250 C after austenitisation at 900 C for 100 minutes produced bainitic matrix structure in both of the investigated ductile irons. Abrasive wear tests performed by rubbing the as cast and austempered specimens on Al{sub 2}O{sub 3} abrasive bands, revealed that austempering treatment improves abrasion resistance about 10-70% depending on the abrasive particle size and composition of the base iron. In the as cast condition, pearlitic GGG 80 grade ductile iron, has higher wear resistance than ferritic GGG 50 grade ductile iron. In the austempered condition GGG 50 and GGG 80 grade ductile irons which have bainitic matrix structure, exhibit almost similar wear resistance. (orig.)


    HUANG Xi-bin; YUAN Yin-zhong


    The wall surface of material is prone to silt abrasion by high-velocity sediment-laden flow. The silt abrasion is different form cavitation erosion. In this article, the characteristics of silt abrasion were discussed. The mechanism of silt abrasion was analyzed and the formation and development of ripple shape on wall surface of material were explained thereafter. Based on turbulence theory and test data, some formulas were derived for predicting the abrasion rate of concrete wall surface in high-velocity sediment-laden flow. The calculated results show good agreement with the experimental data.

  14. Test study and model analysis of cutting polysilicon ingot by micro-abrasive water jet%微磨料水射流对多品硅切割的试验研究与模型分析

    李志荣; 封志明; 郭宗环


    笔者根据材料冲蚀磨损原理,分析探讨了微磨料水射流切割多晶硅硅锭的机理。并运用后混合微磨料射流切割装置,对多晶硅硅锭进行了单因素切割试验,从而获得了切割性能曲线。研究结果表明,微磨料水射流对多晶硅的切割完全可行,射流压力和横移速度是重要的试验数据。通过对高压磨料水射流切割挂能的预测和加工参数的优化,最终建立切割表面质量经验模型,根据模型分析得出射流压力、横移速度与切割质量之间的关系。%Based on the principle of material erosion and abrasion, the paper discussed the mechanism of cutting polysilicon ingot by water jet. The single-factor test of cutting polysilicon ingot by mixed micro-abrasive water jet device was carried out, and the cutting performance curves were obtained. The study results showed that cutting polysilicon by micro-abrasive water jet was feasible. Jet pressure and cross speed were important test data. At the time of increasing the cutting depth, the jet pressure could be a bit higher and the cross speed of the nozzle could be a bit lower, so as to enhance the cutting efficiency. After the prediction of high-pressure abrasive water jet cutting performance and the optimization of machining parameters, the experiential model of cutting surface quality was built, and the relationshi[a among jet pressure, cross speed and cutting quality were identified.

  15. Evaluation of particles released from single-wall carbon nanotube/polymer composites with or without thermal aging by an accelerated abrasion test.

    Jiang, Lin; Kondo, Akira; Shigeta, Masahiro; Endoh, Shigehisa; Uejima, Mitsugu; Ogura, Isamu; Naito, Makio


    To provide data required for assessing the environmental health and safety risks of nanocomposites, abrasion-induced particle release from single-wall carbon nanotube (SWCNT)/polymer composites with or without thermal aging were evaluated by a shot blast system. First, overall composite weight loss (i.e., overall particle release) as a result of shot blasting was measured. Incorporating 5 wt% SWCNTs in polystyrene (PS) matrix was observed to reduce overall particle release by approximately 30% compared with pure PS. Heat treatment of the 5 wt% SWCNT/PS composites at 100°C for 10 days induced very slight change in overall particle release due to shot blasting. However, heat treatment at 350°C for 1 hr greatly deteriorated the abrasion resistance of the composites, enhancing overall particle release. Second, to verify the existence and form of SWCNTs released from the composites, released particles were observed by electron microscopy. Micron-sized particles with protruding SWCNTs and submicron-sized SWCNT clusters were observed in the particles released from the composites. Heat treatment of the composites at 350°C for 1 hr enhanced SWCNT release, which mainly formed clusters or rope-like bundles.

  16. The Effect of Microstructure on the Abrasion Resistance of Low Alloyed Steels

    Xu, X.


    The thesis attempts to develop advanced high abrasion resistant steels with low hardness in combination with good toughness, processability and low alloying additions. For this purpose, a novel multi-pass dual-indenter (MPDI) scratch test approach has been developed to approach the real continuous abrasion process and unravel abrasion damage formation in construction steels, i.e. carrying out scratch tests using a large indenter with different pre-loads to generate a wide pre-scratch with sta...

  17. Impact–abrasion wear characteristics of in-situ VC-reinforced austenitic steel matrix composite

    Moghaddam, E.G., E-mail: [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, Tehran (Iran, Islamic Republic of); Karimzadeh, N. [Department of Materials Engineering, Islamic Azad University, Najafabad Branch, Isfahan (Iran, Islamic Republic of); Varahram, N.; Davami, P. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, Tehran (Iran, Islamic Republic of)


    In this investigation, in-situ precipitation of vanadium carbides was employed to reinforce Fe–13Mn and Fe–13Mn–3W alloys by means of conventional melting and casting route. Microstructures were characterized by optical and scanning electron microscopy techniques. Mechanical properties of the materials were determined by hardness, impact toughness and tension tests. It was observed that tungsten improved the strength of the matrix and the reinforcements as well as tensile properties and work hardening rate of the VC-reinforced composite. Ball mill abrasion test was utilized to simulate impact–abrasion wear condition using two types of abrasive minerals. The results showed that the degree of benefit to be gained by the use of in-situ VC-reinforced composite materials depends strongly on crush strength of the abrasives. It was found that the studied particle-reinforced composite materials were only advantageous when the abrasives were relatively soft, providing low-stress abrasion condition.


    陈洪凯; 唐红梅; 吴四飞


    As one weak topic in research of debris flow, abrasion of debris flow shortens obviously application life of control structure composed of concrete. High-speed drainage structure, one of the most effective techniques to control giant debris flow disaster, has shortened one-third application life due to abrasion by debris flow. Based on velocity calculation method founded by two-phase theory, research of abrasion mechanism of debris flow to high-speed drainage structure was made. The mechanism includes both abrasion mechanism of homogeneous sizing and shearing mechanism of particle of debris flow to high-speed drainage trough structure. Further abrasion equations of both sizing and particle were established by Newton movement theory of debris flow. And abrasion amount formula of the high-speed drainage trough structure is set up by dimensional analysis. Amount to calculating in the formula is consistent with testing data in-situ, which is valuable in design of high-speed drainage structure.

  19. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study.

    Tan, Melissa H X; Hill, Robert G; Anderson, Paul


    Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38-80 μm) versus the conventional alumina abrasive (29 μm) in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine.

  20. Comparing the Air Abrasion Cutting Efficacy of Dentine Using a Fluoride-Containing Bioactive Glass versus an Alumina Abrasive: An In Vitro Study

    Melissa H. X. Tan


    Full Text Available Air abrasion as a caries removal technique is less aggressive than conventional techniques and is compatible for use with adhesive restorative materials. Alumina, while being currently the most common abrasive used for cutting, has controversial health and safety issues and no remineralisation properties. The alternative, a bioactive glass, 45S5, has the advantage of promoting hard tissue remineralisation. However, 45S5 is slow as a cutting abrasive and lacks fluoride in its formulation. The aim of this study was to compare the cutting efficacy of dentine using a customised fluoride-containing bioactive glass Na0SR (38–80 μm versus the conventional alumina abrasive (29 μm in an air abrasion set-up. Fluoride was incorporated into Na0SR to enhance its remineralisation properties while strontium was included to increase its radiopacity. Powder outflow rate was recorded prior to the cutting tests. Principal air abrasion cutting tests were carried out on pristine ivory dentine. The abrasion depths were quantified and compared using X-ray microtomography. Na0SR was found to create deeper cavities than alumina (p<0.05 despite its lower powder outflow rate and predictably reduced hardness. The sharper edges of the Na0SR glass particles might improve the cutting efficiency. In conclusion, Na0SR was more efficacious than alumina for air abrasion cutting of dentine.

  1. New concepts in air abrasion.

    Porth, R N


    There is no doubt that air abrasion is going to be part of the millennial shift in dentistry away from traditional treatment modalities. With the change in incidence and morphology of caries as a result of the hardening effect of fluoride on enamel, this ability to remove only decayed areas and permanently seal the less susceptible areas becomes increasingly desirable.

  2. Research on Premixed Abrasive Jet Derusting Machine


    The structure, working principles, and main technological parameters of the premajet derusting machineare introduced. Experiments were made to test the relationship among such jet parameters as working pressure,rate of water flow, abrasive weight consistency and derusting efficiency. Reasonable parameters were decided. Re-su lts prove that the derusting machine is characterized by its high derusting efficiency (as high as 20 m2/h), goodderusting quality (as good as ISO8501-1 Sa 2.5), and low specific power consumption (about 0.3 kW · h/m2).Therefore it is a new type of high efficiency derusting machine.

  3. 30 CFR 72.610 - Abrasive blasting.


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Abrasive blasting. 72.610 Section 72.610... HEALTH STANDARDS FOR COAL MINES Miscellaneous § 72.610 Abrasive blasting. (a) Surface and underground mines. When an abrasive blasting operation is performed, all exposed miners shall properly...

  4. 30 CFR 58.610 - Abrasive blasting.


    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Abrasive blasting. 58.610 Section 58.610... SAFETY AND HEALTH HEALTH STANDARDS FOR METAL AND NONMETAL MINES Miscellaneous § 58.610 Abrasive blasting. (a) Surface and underground mines. When an abrasive blasting operation is performed, all...

  5. Visualisation of Abrasive Particles in Suction Part of Abrasive Cutting Head

    M. Zeleňák; Klich, J. (Jiří); Hlaváček, P.; Foldyna, J. (Josef); Sitek, L. (Libor)


    The development of numerical model of processes occurring in the abrasive water jet cutting head during the process of creation and forming of abrasive water jet is currently in the progress at the Institute of Geonics in Ostrava. Verification of the model requires among others to determine behaviour of abrasive particles at the input of the cutting head. Therefore, visualisation of abrasive particles at the input using various parameters of abrasive jet and subsequent analysis was...

  6. A Profilometric Study to Assess the Role of Toothbrush and Toothpaste in Abrasion Process

    Sandeep Kumar


    Full Text Available Statement of the Problem: Despite of many studies conducted on toothbrushes and toothpaste to find out the culprit for abrasion, there is no clear cut evidence to pin point the real cause for abrasion. Purpose: An in vitro assessment of the role of different types of toothbrushes (soft/ medium/hard in abrasion process when used in conjunction with and without a dentifrice. Materials and Method: Forty five freshly extracted, sound, human incisor teeth were collected for this study. Enamel specimens of approximately 9 mm2 were prepared by gross trimming of extracted teeth using a lathe machine (Baldor 340 Dental lathe; Ohio, USA. They were mounted on separate acrylic bases. The specimens were divided into three groups, each group containing 15 mounted specimens. Group 1 specimens were brushed with soft toothbrush; Group 2 brushed with medium toothbrush and Group 3 with hard toothbrush. Initially, all the mounted specimens in each group were brushed using dentifrice and then the same procedure was repeated with water as control. Profilometric readings were recorded pre and post to tooth brushing and the differences in readings served as proxy measure to assess surface abrasion. These values were then compared to each other. Kruskal Wallis and Mann-Whitney U test were performed. Results: The results showed that brushing, with water alone, caused less abrasion than when toothpaste was added (p< 0.008. When brushed with water, the harder toothbrush caused more abrasion (higher Ra-value, but when toothpaste was added, the softer toothbrush caused more abrasion (p< 0.001. Conclusion: Besides supporting the fact that toothpaste is needed to create a significant abrasion, this study also showed that a softer toothbrush can cause more abrasion than harder ones. The flexibility of bristles is only secondary to abrasion process and abrasivity of dentifrice has an important role in abrasion process.

  7. Air flow exploration of abrasive feed tube

    Zhang, Shijin; Li, Xiaohong; Gu, Yilei


    An abrasive water-jet cutting process is one in which water pressure is raised to a very high pressure and forced through a very small orifice to form a very thin high speed jet beam. This thin jet beam is then directed through a chamber and then fed into a secondary nozzle, or mixing tube. During this process, a vacuum is generated in the chamber, and garnet abrasives and air are pulled into the chamber, through an abrasive feed tube, and mixes with this high speed stream of water. Because of the restrictions introduced by the abrasive feed tube geometry, a vacuum gradient is generated along the tube. Although this phenomenon has been recognized and utilized as a way to monitor nozzle condition and abrasive flowing conditions, yet, until now, conditions inside the abrasive feed line have not been completely understood. A possible reason is that conditions inside the abrasive feed line are complicated. Not only compressible flow but also multi-phase, multi-component flow has been involved in inside of abrasive feed tube. This paper explored various aspects of the vacuum creation process in both the mixing chamber and the abrasive feed tube. Based on an experimental exploration, an analytical framework is presented to allow theoretical calculations of vacuum conditions in the abrasive feed tube.

  8. Behavior of HVOF WC-10Co4Cr Coatings with Different Carbide Size in Fine and Coarse Particle Abrasion

    Ghabchi, Arash; Varis, Tommi; Turunen, Erja; Suhonen, Tomi; Liu, Xuwen; Hannula, S.-P.


    A modified ASTM G 65 rubber wheel test was employed in wet and dry conditions using 220 nm titania particles and 368 μm sand particles, respectively. Both tests were conducted on WC-CoCr coatings produced with two powders with different carbide grain sizes (conventional and sub-micron) to address the effect of carbide size and abrasive medium characteristics on the wear performance. The same spot before and after the wet abrasion wear testing was analyzed in detail using SEM to visualize wear mechanisms. It was shown that the wear mechanism depends on the relative size of the carbide and abrasive particles. Wear mechanisms in dry sand abrasion were studied by analyzing the single scratches formed by individual abrasive particles. Interaction of surface open porosity with moving abrasive particles causes formation of single scratches. By tailoring the carbide size, the wear performance can be improved.

  9. Electrical resistivity measurements to predict abrasion resistance of rock aggregates

    Sair Kahraman; Mustafa Fener


    The prediction of Los Angeles (LA) abrasion loss from some indirect tests is useful for practical applications. For this purpose, LA abrasion, electrical resistivity, density and porosity tests were carried out on 27 different rock types. LA abrasion loss values were correlated with electrical resistivity and a good correlation between the two parameters was found. To see the effect of rock class on the correlation, regression analysis was repeated for igneous rocks, metamorphic rocks and sedimentary rocks, respectively. It was seen that correlation coefficients were increased for the rock classes. In addition, the data were divided into two groups according to porosity and density, respectively. After repeating regression analysis for these porosity and density groups, stronger correlations were obtained compared to the equation derived for all rocks. The validity of the derived equations was statistically tested and it was shown that all derived equations were significant. Finally, it can be said that all derived equations can alternatively be used for the estimation of LA abrasion loss from electrical resistivity.

  10. Wear characterization of abrasive waterjet nozzles and nozzle materials

    Nanduri, Madhusarathi

    Parameters that influence nozzle wear in the abrasive water jet (AWJ) environment were identified and classified into nozzle geometric, AWJ system, and nozzle material categories. Regular and accelerated wear test procedures were developed to study nozzle wear under actual and simulated conditions, respectively. Long term tests, using garnet abrasive, were conducted to validate the accelerated test procedure. In addition to exit diameter growth, two new measures of wear, nozzle weight loss and nozzle bore profiles were shown to be invaluable in characterizing and explaining the phenomena of nozzle wear. By conducting nozzle wear tests, the effects of nozzle geometric, and AWJ system parameters on nozzle wear were systematically investigated. An empirical model was developed for nozzle weight loss rate. To understand the response of nozzle materials under varying AWJ system conditions, erosion tests were conducted on samples of typical nozzle materials. The effect of factors such as jet impingement angle, abrasive type, abrasive size, abrasive flow rate, water pressure, traverse speed, and target material was evaluated. Scanning electron microscopy was performed on eroded samples as well as worn nozzles to understand the wear mechanisms. The dominant wear mechanism observed was grain pullout. Erosion models were reviewed and along the lines of classical erosion theories a semi-empirical model, suitable for erosion of nozzle materials under AWJ impact, was developed. The erosion data correlated very well with the developed model. Finally, the cutting efficiency of AWJ nozzles was investigated in conjunction with nozzle wear. The cutting efficiency of a nozzle deteriorates as it wears. There is a direct correlation between nozzle wear and cutting efficiency. The operating conditions that produce the most efficient jets also cause the most wear in the nozzle.

  11. Two-Body Abrasive Wear of the Surfaces of Pangolin Scales

    Jin Tong; Tie-biao Lü; Yun-hai Ma; Heng-kun Wang; Lu-quan Ren; R. D. Arnell


    The Pangolin, a soil-burrowing animal, is covered with scales. These scales are often abraded by soil and rock and their surface is corrugated. The abrasive wear of the surface of the scales was examined. The scales were taken from a pangolin that had died of natural causes. The tests were run on a rotary disc abrasive wear tester. The abrasive material was quartz sand (96.5 wt.%) and bentonite (3.5 wt.%). The morphology of the abraded surfaces and the abrasion were examined by stereoscopic microscopy and scanning electron microscopy. The concepts are proposed of "Guiding-Effect" and "Rolling-Effect" on the textured surfaces under free abrasive wear conditions and the critical dimensions of the "Rolling-Effect" are discussed.

  12. Progress in abrasive and grinding technology

    Xu, Xipeng


    The grinding and abrasive processing of materials are machining techniques which use bonded or loose abrasives to remove material from workpieces. Due to the well-known advantages of grinding and abrasive processes, advances in abrasive and grinding technology are always of great import in enhancing both productivity and component quality. In order to highlight the recent progress made in this field, the editor invited 21 world-wide contributions with the aim of gathering together all of the achievements of leading researchers into a single publication. The authors of the 21 invited papers, of

  13. An Investigation of Abrasive Wear Behaviour of Al 2014-SiC Composites

    Çalin, Recep; Cilasun, Niyazi Selçuk


    In this study, the effects of SiC reinforcement volume fractions on hardness, porosity and abrasive wear behaviour were examined in Al 2014-SiC (composites (MMCs) of 3%, 6% and 12% reinforcement-volume (R-V) ratios produced by melt-stirring. Abrasive wear tests were carried out by 320 mesh Al2O3 abrasive paper and a pin-on-disc wear test apparatus, under 10N, 20N and 30N load, and at 0.2 ms-1 sliding speed. The same specimens were tested by 150, 240 and 320 mesh abrasive paper at 0.2 ms-1 sliding speed, under 10N, 20N and 30N load. After the tests, the microstructures of the worn surfaces were examined with scanning electron microscope (SEM) studies and EDS analyses. Besides, the amount of hardness and porosity of the specimens were identified. It was recorded that the amounts of hardness and porosity increases as the SiC reinforcement in the composite increases. The highest amount of abrasive wear was recorded in the specimens with 3% reinforcements. It was identified that the amount of abrasive wear decreases while the SiC reinforcement in the composite structure increases by volume, and that the amount of porosity and reinforcement volume (R-V) ratio are important parameters in abrasive wear.

  14. Exposure to crystalline silica in abrasive blasting operations where silica and non-silica abrasives are used.

    Radnoff, Diane L; Kutz, Michelle K


    Exposure to respirable crystalline silica is a hazard common to many industries in Alberta but particularly so in abrasive blasting. Alberta occupational health and safety legislation requires the consideration of silica substitutes when conducting abrasive blasting, where reasonably practicable. In this study, exposure to crystalline silica during abrasive blasting was evaluated when both silica and non-silica products were used. The crystalline silica content of non-silica abrasives was also measured. The facilities evaluated were preparing metal products for the application of coatings, so the substrate should not have had a significant contribution to worker exposure to crystalline silica. The occupational sampling results indicate that two-thirds of the workers assessed were potentially over-exposed to respirable crystalline silica. About one-third of the measurements over the exposure limit were at the work sites using silica substitutes at the time of the assessment. The use of the silica substitute, by itself, did not appear to have a large effect on the mean airborne exposure levels. There are a number of factors that may contribute to over-exposures, including the isolation of the blasting area, housekeeping, and inappropriate use of respiratory protective equipment. However, the non-silica abrasives themselves also contain silica. Bulk analysis results for non-silica abrasives commercially available in Alberta indicate that many contain crystalline silica above the legislated disclosure limit of 0.1% weight of silica per weight of product (w/w) and this information may not be accurately disclosed on the material safety data sheet for the product. The employer may still have to evaluate the potential for exposure to crystalline silica at their work site, even when silica substitutes are used. Limited tests on recycled non-silica abrasive indicated that the silica content had increased. Further study is required to evaluate the impact of product recycling

  15. Comparing Effects of Four Toothpaste Types (Nasim, Crest 7, Crest Sensitivity and Daroghar3) on Rate of Enamel Abrasion


    Introduction: Toothpaste should have the most plaque removal efficacy with the least abrasiveness. The aim of this study was to evaluate enamel abrasion induced by four toothpaste types. Methods: In this in vitro experimental study, 24 dental samples were divided into four groups of six. The initial surface roughness was measured with the roughness measuring device. Regarding abrasion test with Daroghar3, Nasim, Crest7 and Crest sensitivity toothpastes, samples were located in V8cross brus...

  16. A Study of the Pickup of Abrasive Particles during Abrasion of Annealed Aluminum on Silicon Carbide Abrasive Papers,

    annealed aluminium during abrasion on silicon carbide abrasive papers. Neither optical nor scanning electron microscopy adequately characterises the...despite its limitations when examining rough surfaces. The present results show that the pickup of silicon carbide particles increases with increase in

  17. 21 CFR 872.6010 - Abrasive device and accessories.


    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6010 Abrasive device and accessories... disk, guard for an abrasive disk, abrasive point, polishing agent strip, and polishing wheel....

  18. Surface roughness and gloss of current CAD/CAM resin composites before and after toothbrush abrasion.

    Koizumi, Hiroyasu; Saiki, Osamu; Nogawa, Hiroshi; Hiraba, Haruto; Okazaki, Tomoyo; Matsumura, Hideo


    The purpose of this study was to evaluate the gloss and surface roughness behaviors of newly developed CAD/CAM composite blocks with different filler contents and characteristics. The gloss and surface roughness were quantified before and after a toothbrush dentifrice abrasion test; the results were compared to the gloss and surface roughness of a ceramic CAD/CAM block. Knoop hardness was determined before abrasion test. The results were analyzed by ANOVA, Tukey HSD, and Dunnett t test (pVita Enamic>Gradia block>Shofu Block HC, Lava Ultimate≥Katana Avencia block≥Cerasmart. After toothbrush abrasion, a significant difference in the gloss unit was detected between the Shofu Block HC material and the ceramic block. The Ra and Rz of the Cerasmart and Shofu Block HC materials were significantly larger than those of the ceramic block after toothbrush abrasion.

  19. Abrasion properties of homogenous and blended fill materials during pressure hydraulic transport

    Turchaninov, S.P.


    A description is given of tests conducted to determine the abrasive properties of small and large-grain free-flowing fill materials during hydraulic transport of the materials under pressure. Data are given on the size, density, abrasiveness of various sized varieties of rock, sand, and blends comprising homogenous materials, simple and complex mixtures, and on the physical characteristics of various fill materials in relation to the trafficability and parameters of pipelines. Technical specifications are given for fill steel pipes. The study indicates that the durability of hydraulic fill pipelines largely depends on the abrasiveness of the fill materials. 3 references, 2 figures, 2 tables.

  20. Brushing abrasion of luting cements under neutral and acidic conditions.

    Buchalla, W; Attin, T; Hellwig, E


    Four resin based materials (Compolute Aplicap, ESPE; Variolink Ultra, Vivadent; C&B Metabond, Parkell and Panavia 21, Kuraray), two carboxylate cements (Poly-F Plus, Dentsply DeTrey and Durelon Maxicap, ESPE), two glass-ionomer cements (Fuji I, GC and Ketac-Cem Aplicap, ESPE), one resin-modified glass ionomer cement (Vitremer, 3M) one polyacid-modified resin composite (Dyract Cem, Dentsply DeTrey) and one zinc phosphate cement (Harvard, Richter & Hoffmann) were investigated according to their brushing resistance after storage in neutral and acidic buffer solutions. For this purpose 24 cylindrical acrylic molds were each filled with the materials. After hardening, the samples were stored for seven days in 100% relative humidity and at 37 degrees C. Subsequently, they were ground flat and polished. Then each specimen was covered with an adhesive tape leaving a 4 mm wide window on the cement surface. Twelve samples of each material were stored for 24 hours in a buffer solution with a pH of 6.8. The remaining 12 samples were placed in a buffer with a pH of 3.0. All specimens were then subjected to a three media brushing abrasion (2,000 strokes) in an automatic brushing machine. Storage and brushing were performed three times. After 6,000 brushing strokes per specimen, the tape was removed. Brushing abrasion was measured with a computerized laser profilometer and statistically analyzed with ANOVA and Tukey's Standardized Range Test (p < or = 0.05). The highest brushing abrasion was found for the two carboxylate cements. The lowest brushing abrasion was found for one resin based material, Compolute Aplicap. With the exception of three resin-based materials, a lower pH led to a higher brushing abrasion.

  1. Micro-abrasion-corrosion behaviour of a biomedical Ti-25Nb-3Mo-3Zr-2Sn alloy in simulated physiological fluid.

    Wang, Zhenguo; Li, Yan; Huang, Weijiu; Chen, Xiaoli; He, Haoran


    The micro-abrasion-corrosion behaviour of the biomedical Ti-25Nb-3Mo-3Zr-2Sn alloy in Hank׳s solution with protein has been investigated using electrochemical measurements, tribological tests and scanning electron microscope (SEM) observations. The potentiodynamic polarization tests showed that the corrosion potential (Ecorr) exhibits the maximum value at the abrasive concentration of 0.05gcm(-3) despite of the load level. The tribological results indicated that the total material loss of the Ti-25Nb-3Mo-3Zr-2Sn alloy during micro-abrasion increased with the increasing abrasive concentration at a certain applied load. When the abrasive concentration is no more than 0.15gcm(-3), the total material loss increases with increasing load, while the total material loss exhibits the maximum value at a moderate load in case of higher abrasive concentration levels. This was ascribed to the three-body or two-body micro-abrasion-corrosion at different abrasive concentration levels. The wastage map, abrasion mode map and synergy map associated with the applied load and the abrasive concentration were constructed to evaluate the micro-abrasion-corrosion behaviour of the Ti-25Nb-3Mo-3Zr-2Sn alloy in potential biomedical applications.

  2. Abrasive wear property of laser melting/deposited Ti2Ni/TiNi intermetallic alloy


    A wear resistant intermetallic alloy consisting of TiNi primary dendrites and Ti2Ni matrix was fabricated by the laser melting deposition manufacturing process. Wear resistance of Ti2Ni/TiNi alloy was evaluated on an abrasive wear tester at room temperature under the different loads. The results show that the intermetallic alloy suffers more abrasive wear attack under low wear test load of 7, 13 and 25 N than high-chromium cast-iron. However, the intermetallic alloy exhibits better wear resistance under wear test load of 49 N. Abrasive wear of the laser melting deposition Ti2Ni/TiNi alloy is governed by micro-cutting and plowing.Pseudoelasticity of TiNi plays an active role in contributing to abrasive wear resistance.

  3. Life cycle and sustainability of abrasive tools

    Linke, Barbara


    This monograph focuses on abrasive tools for grinding, polishing, honing, and lapping operations. The book describes the life cycle of abrasive tools from raw material processing of abrasive grits and bonding, manufacturing of monolithic or multi-layered tools, tool use to tool end-of-life. Moreover, this work highlights sustainability challenges including economic, environmental, social and technological aspects. The target audience primarily comprises research and industry experts in the field of manufacturing, but the book may also be beneficial for graduate students.

  4. Abrasion behavior of graphite pebble in lifting pipe of pebble-bed HTR

    Shen, Ke; Su, Jiageng [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Zhou, Hongbo [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Chinergy Co., LTD., Beijing 100193 (China); Peng, Wei; Liu, Bing [Institute of Nuclear and New Energy Technology, Advanced Nuclear Energy Technology Cooperation Innovation Center, The Key Laboratory of Advanced Nuclear Engineering and Safety, Ministry of Education, Beijing 10084 (China); Yu, Suyun, E-mail: [Center for Combustion Energy, The Key Laboratory for Thermal Science and Power Engineering, Ministry of Educations, Tsinghua University, Beijing 10084 (China)


    Highlights: • Quantitative determination of abrasion rate of graphite pebbles in different lifting velocities. • Abrasion behavior of graphite pebble in helium, air and nitrogen. • In helium, intensive collisions caused by oscillatory motion result in more graphite dust production. - Abstract: A pebble-bed high-temperature gas-cooled reactor (pebble-bed HTR) uses a helium coolant, graphite core structure, and spherical fuel elements. The pebble-bed design enables on-line refueling, avoiding refueling shutdowns. During circulation process, the pebbles are lifted pneumatically via a stainless steel lifting pipe and reinserted into the reactor. Inevitably, the movement of the fuel elements as they recirculate in the reactor produces graphite dust. Mechanical wear is the primary source of graphite dust production. Specifically, the sources are mechanisms of pebble–pebble contact, pebble–wall (structural graphite) contact, and fuel handling (pebble–metal abrasion). The key contribution to graphite dust production is from the fuel handling system, particularly from the lifting pipe. During pneumatic lift, graphite pebbles undergo multiple collisions with the stainless steel lifting pipe, thereby causing abrasion of the graphite pebbles and producing graphite dust. The present work explored the abrasion behavior of graphite pebble in the lifting pipe by measuring the abrasion rate at different lifting velocities. The abrasion rate of the graphite pebble in helium was found much higher than those in air and nitrogen. This gas environment effect could be explained by either tribology behavior or dynamic behavior. Friction testing excluded the possibility of tribology reason. The dynamic behavior of the graphite pebble was captured by analysis of the audio waveforms during pneumatic lift. The analysis results revealed unique dynamic behavior of the graphite pebble in helium. Oscillation and consequently intensive collisions occur during pneumatic lift, causing

  5. The influence of mixing water and abrasives on the quality of machined surface

    A. Stoić


    Full Text Available This paper shows the impact of mixing water and abrasives in water jet cutting process on the quality of the machined surface. The tests were done with polymer material SIPAS, where the influence of cutting parameters was researched (cutting pressure, cutting feed and abrasive mass flow. The surface roughness was measured on several zones, regarding the depth of materials, because the roughness is increased with the material thickness.

  6. Shotcup petal abrasions in close range .410-caliber shotgun injuries.

    Dowling, G P; Dickinson, J A; Cooke, C T


    Shotcup petal abrasions centered around a shotgun wound of entrance are generally thought to occur at a range of 30 to 90 cm. A suicidal .410-caliber shotgun injury of the right eye is described in which typical petal abrasions were noted around the entrance wound. However, significant soot deposition around the wound suggested that the range of fire was less than 30 cm and perhaps closer to 15 cm. Test-firing of the weapon and ammunition used by the decedent showed some spread of the shotcup petals at a range of 7.5 cm, progressing to maximum spread at 30 to 52.5 cm. Further testing with other .410 ammunition, containing shotcups, confirmed the spread of shotcup petals at ranges less than 30 cm, irrespective of manufacturer, shotshell length, and birdshot size. When a variety of shotguns were tested, it was found that one weapon with a very short barrel and cylinder bore did not exhibit petal spread until a range of 30 cm was reached. The remaining shotguns, with longer barrels and full choke, all demonstrated definite petal spread at a range of 12.5 cm. The long, narrow configuration of .410 shotcup petals may explain their early spread and the production of petal abrasions at ranges of less than 30 cm.

  7. Performance of recycling abrasives in rock cutting by abrasive water jet

    Gokhan Aydin


    Rock cutting performance of recycling abrasives was investigated in terms of cutting depth, kerf width, kerf taper angle and surface roughness. Gravity separation technique was employed to separate the abrasives and the rock particles. The recycling abrasive particles were then dried and sieved for determination of their disintegration behaviors. Before each cutting with recycling abrasives, the abrasive particles less than 106mm were screened out. It is revealed that a considerable amount of used abrasives can be effectively reused in the rock cutting. The reusabilities of abrasives are determined as 81.77%, 57.50%, 34.37%and 17.72%after the first, second, third and fourth cuttings, respectively. Additionally, it is determined that recycling must be restricted three times due to the excessive disintegration of abrasives with further recycling. Moreover, it is concluded that cutting depth, kerf width and surface roughness decreases with recycling. No clear trend is found between the kerf taper angle and recycling. Particle size distribution is determined as an important parameter for improving the cutting performance of recycling abrasives.

  8. A physically-based abrasive wear model for composite materials

    Lee, Gun Y.; Dharan, C.K.H.; Ritchie, Robert O.


    A simple physically-based model for the abrasive wear of composite materials is presented based on the mechanics and mechanisms associated with sliding wear in soft (ductile) matrix composites containing hard (brittle) reinforcement particles. The model is based on the assumption that any portion of the reinforcement that is removed as wear debris cannot contribute to the wear resistance of the matrix material. The size of this non-contributing portion of the reinforcement is estimated by modeling the three primary wear mechanisms, specifically plowing, interfacial cracking and particle removal. Critical variables describing the role of the reinforcement, such as its relative size and the nature of the matrix/reinforcement interface, are characterized by a single contribution coefficient, C. Predictions are compared with the results of experimental two-body (pin-on drum) abrasive wear tests performed on a model aluminum particulate-reinforced epoxy matrix composite material.

  9. Machining of the Flat Surfaces with Abrasive-metallic Lapping Tools

    Adam Barylski


    The constructional principle of abrasion metal disc is that abrasive insertions are spread uniformly on the working surface of a metal base. During lapping by means of such tools only the machining fluid is dosed and that by drop.Abrasive elements of circular shape pellets are produced by mixing boron carbide BC400 micrograins with electrographite components, the pellets were pressed with a load of about 12 kN. Next they were heated in furnace at about 520K for hours,then cooled together with the furnace. Tests were carried out on the making of circular abrasive insertions of which the main components were born carbide and micrograins of electric copper mixed the epoxide resins.

  10. Machining of the Flat Surfaces with Abrasive-metallic Lapping Tools



    The constructional principle of abrasion metal disc is that abrasive insertions are spread uniformly on the working surface of a metal base. During lapping by means of such tools only the machining fluid is dosed and that by drop. Abrasive elements of circular shape pellets are produced by mixing boron carbide BC400 micrograins with electrographite components, the pellets were pressed with a load of about 12 kN. Next they were heated in furnace at about 520K for hours, then cooled together with the furnace. Tests were carried out on the making of circular abrasive insertions of which the main components were born carbide and micrograins of electric copper mixed the epoxide resins.

  11. Development of underwater cutting system by abrasive water-jet

    Demura, Kenji; Yamaguchi, Hitoshi


    The technology to cut objects in the ocean's depths with abrasive water jets was examined for possible application in view of the greater water depths and sophistication involved in work on the ocean floor today. A test model was developed to study this technology's safety and practicability. The test model was designed for use at great water depths and has functions and a configuration that are unlike equipment used on land. A continuous, stable supply of abrasive is a distinctive design feature. In land applications, there had been problems with plugged tubes and an uneven supply. For this reason, the abrasive was converted to slurry form, and a continuous pressurized tube pump system was adopted for supply to the nozzle head. Also, a hydraulic motor that does not employ oil or electric power was used to provide an underwater drive that is environment-friendly. The report outlines the technology's general design concept including its distinctive functions and its configuration for use at great depths, and the report provides great detail on the equipment.

  12. Characterization of Effective Parameters in Abrasive Waterjet Rock Cutting

    Oh, Tae-Min; Cho, Gye-Chun


    The rock cutting performance of an abrasive waterjet is affected by various parameters. In this study, rock cutting tests are conducted with different energy (i.e., water pressure, traverse speed, and abrasive feed rate), geometry (i.e., standoff distance), and material parameters [i.e., uniaxial compressive strength (UCS)]. In particular, experimental tests are carried out at a long standoff distance (up to 60 cm) to consider field application. The effective parameters of the rock cutting process are identified based on the relationships between the cutting performance indices (depth, width, and volume) and parameters. In addition, the cutting efficiency is analyzed with effective parameters as well as different pump types and the number of cutting passes considering the concept of kinetic jet energy. Efficiency analysis reveals that the cutting depth efficiency tends to increase with an increase in the water pressure and traverse speed and with a decrease in the standoff distance and UCS. Cutting volume efficiency strongly depends on standoff distance. High efficiency of cutting volume is obtained at a long standoff distance regardless of the pump type. The efficiency analysis provides a realistic way to optimize parameters for abrasive waterjet rock excavation.

  13. 旋风式砂带磨削机及钢丝磨削试验研究%Research on Cyclone Abrasive Belt Grinding Machine and Steel Wire Grinding Test

    卢剑锋; 李家春; 张萍


    Abrasive belt grinder plays an important role in machining field. It can meet a variety of processing requirements. The concept of abrasive belt grinding was introduced briefly. The working principle and main structure of a new belt grinder for removing rust on steel wire surface were illustrated. Then the relationships among the grinding force,the metal removal rate,belt wear rate, grinding ratio,grinding depth and wire walking speed were studied through experiment. The research work provides rational parameters for wire snagging line with abrasive belt.%砂带磨削在机械加工领域发挥着越来越大的作用,可满足各种加工要求。简单介绍了砂带磨削的概念,阐述了一个针对钢丝表面除锈的新型砂带磨削设备的工作原理及其机床的主要机构,并通过试验研究磨削压力、金属去除率、砂带磨损、磨削比、磨削深度、钢丝走速之间的关系,为砂带修磨线材生产线提供了合理的磨削工艺参数。

  14. Evaluation of Rheological Properties of Gel Abrasive in Magnetic Abrasive Finishing

    A-Cheng Wang


    Full Text Available The purpose of this study was aimed at the evaluation of the mechanism of magnetic finishing with gel abrasive (MFGA, during which the performance of MFGA was compared to that of magnetic abrasive finishing (MAF. Of importance is that MFGA performs better than MAF based on the polishing-efficiency criterion. Silicone gels, however, are semisolid polymer gels with deforming properties that are temperature dependent, ultimately influencing significantly the polishing efficiency in MFGA. Therefore, taking as examples cylindrical rods which were polished using silicone gels with different plasticities to determine the corresponding temperatures of abrasive media in the working area, this study evaluated the MFGA mechanism to elucidate the properties of silicone gels and attain both the finished effect and effective gel abrasives in MFGA to produce a highly efficient polished surface. Next, circulating effects of abrasive media were identified to ensure the efficiency in MFGA and establish the relation between the concentrations of abrasive media and circulating effects in the working area. Experimental results show that silicone gels with low plasticity produce high temperature of abrasive media in MFGA; high temperature of abrasive medium makes excellent circulating effects in the working area, inducing high material removal and fine surface roughness.

  15. Dynamic Mechanical Analysis and Three-Body Abrasive Wear Behaviour of Thermoplastic Copolyester Elastomer Composites

    Hemanth Rajashekaraiah


    Full Text Available Various amounts of short fibers (glass and carbon and particulate fillers like polytetrafluoroethylene (PTFE, silicon carbide (SiC, and alumina (Al2O3 were systematically introduced into the thermoplastic copolyester elastomer (TCE matrix for reinforcement purpose. The mechanical properties such as storage modulus, loss modulus, and Tan δ by dynamic mechanical analysis (DMA and three-body abrasive wear performance on a dry sand rubber wheel abrasion tester have been investigated. For abrasive wear study, the experiments were planned according to L27 orthogonal array by considering three factors and three levels. The complex moduli for TCE hybrid composites were pushed to a higher level relative to the TCE filled PTFE composite. At lower temperatures (in the glassy region, the storage modulus increases with increase in wt.% of reinforcement (fiber + fillers and the value is maximum for the composite with 40 wt.% reinforcement. The loss modulus and damping peaks were also found to be higher by the incorporation of SiC and Al2O3 microfillers. The routine abrasive wear test results indicated that TCE filled PTFE composite exhibited better abrasion resistance. Improvements in the abrasion resistance, however, have not been achieved by short-fiber and particlaute filler reinforcements. From the Taguchi’s experimental findings, optimal combination of control factors were obtained for minimum wear volume and also predictive correlations were proposed. Further, the worn surface morphology of the samples was discussed.

  16. Microstructure and abrasion wear behavior of Ni-based laser cladding alloy layer at high temperature

    LIU Yong; LIU Su-qin; WANG Shun-xing


    Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21+20%WC+0.5%CeO2, Ni25+20%WC+0.5%CeO2 and Ni60+20%WC+0.5%CeO2, the experimental results show that Ni21+20%WC+0.5%CeO2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature.

  17. Abrasive wear: The efects of fibres size on oil palm empty fruit bunch polyester composite

    Kasolang, S.; Kalam, A.; Ahmad, M. A.; Rahman, N. A.; Suhadah, W. N.


    This paper presents an experimental investigation carried out to determine the effect of palm oil empty fruit bunch (OPEFB) fibre size in dry sliding testing of polyester composite. These composite samples were produced by mixing raw OPEFB fibre with resin. The samples were prepared at different sizes of fibre (100, 125, 180 and 250μm). Abrasion Resistance Tester (TR-600) was used to carried out abrasive wear tests in dry sliding conditions. These tests were performed at room temperature for two different loads (10 and 30N) and at a constant sliding velocity of 1.4m/s. The specific wear rates of OPEFB polyester composites were obtained. The morphology of composite surface before and after tests was also examined using 3D microscope imaging. Preliminary work on thermal distribution at the abrasive wheel point was also conducted for selected samples.

  18. Basics of cutting and abrasive processes

    Toenshoff, Hans Kurt


    Manufacturing is the basic industrial activity generating real value. Cutting and abrasive technologies are the backbone of precision production in machine, automotive and aircraft building as well as of production of consumer goods. We present the knowledge of modern manufacturing in these technologies on the basis of scientific research. The theory of cutting and abrasive processes and the knowledge about their application in industrial practice are a prerequisite for the studies of manufacturing science and an important part of the curriculum of the master study in German mechanical engineering. The basis of this book is our lecture “Basics of cutting and abrasive processes” (4 semester hours/3 credit hours) at the Leibniz University Hannover, which we offer to the diploma and master students specializing in manufacturing science.

  19. The application of air abrasion in dentistry

    Mandinić Zoran


    Full Text Available One of the main objectives of contemporary dentistry is to preserve healthy tooth structure by applying techniques of noninvasive treatment. Air abrasion is a minimally invasive nonmechanical technique of tooth preparation that uses kinetic energy to remove carious tooth structure. A powerful narrow stream of moving aluminum-oxide particles hit the tooth surface and they abrade it without heat, vibration or noise. Variables that affect speed of cutting include air pressure, particle size, powder flow, tip’s size, angle and distance from the tooth. It has been proposed that air abrasion can be used to diagnose early occlusal-surface lesions and treat them with minimal tooth preparation using magnifier. Reported advantages of air abrasion include reduced noise, vibration and sensitivity. Air abrasion cavity preparations have more rounded internal contours than those prepared with straight burs. This may increase the longevity of placed restorations because it reduces the incidence of fractures and a consequence of decreased internal stresses. However, air abrasion cannot be used for all patients, i.e. in cases involving severe dust allergy, asthma, chronic obstructive lung disease, recent extraction or other oral surgery, open wounds, advanced periodontal disease, recent placement of orthodontic appliances and oral abrasions, or subgingival caries removal. Many of these conditions increase the risk of air embolism in the oral soft tissues. Dust control is a challenge, and it necessitates the use of rubber dam, high-volume evacuation, protective masks and safety eyewear for both the patient and the therapist. [Projekat Ministarstva nauke Republike Srbije, br. 46009

  20. PC controlled toothbrush/dentifrice abrasion machine.

    Bal, G; Uçtaşli, S; Bekiroğlu, E


    A toothbrush/dentifrice abrasion machine was developed to use in dental research laboratory. The mechanism was designed as a hexagonal block driven by two stepping motors which move the mechanism in four directions. In order to control the stepping motors speed, position and direction commands or signals were generated by a software written in C Programming Language and then these commands were applied the stepping motor drives through parallel port of a personal computer. The toothbrush/dentifrice abrasion machine was finally used to measure different longevity of tooth brush. It was experimentally shown that the mechanism can be used for highly accurate position and speed applications.

  1. Predicting Los Angeles abrasion loss of rock aggregates from crushability index

    S Kahraman; O Y Toraman


    Predicting Los Angeles abrasion loss of aggregate material from some simpler tests will be useful for especially preliminary studies. For this reason, to investigate the possibility of predicting the Los Angeles abrasion loss from the crushability index, Los Angeles abrasion, crushability, density and porosity tests were performed on 11 different rock types collected from different areas of Turkey. The results of the tests were analysed using simple and multiple regression analyses. Generally significant correlations were obtained from both simple and multiple regression analyses. The correlation coefficients and estimation capabilities of the two multiple regression equations are slightly higher than that of the simple regression equation. It was concluded that the simple regression equation is practical and reliable enough for estimation purposes. However, the two multiple regression equations can be used for a more accurate estimation.

  2. Surface roughness and wear of resin cements after toothbrush abrasion

    Sérgio Kiyoshi ISHIKIRIAMA


    Full Text Available Increased surface roughness and wear of resin cements may cause failure of indirect restorations. The aim of this study was to evaluate quantitatively the surface roughness change and the vertical wear of four resin cements subjected to mechanical toothbrushing abrasion. Ten rectangular specimens (15 × 5 × 4 mm were fabricated according to manufacturer instructions for each group (n = 10: Nexus 3, Kerr (NX3; RelyX ARC, 3M ESPE (ARC; RelyX U100, 3M ESPE (U100; and Variolink II, Ivoclar/Vivadent (VL2. Initial roughness (Ra, µm was obtained through 5 readings with a roughness meter. Specimens were then subjected to toothbrushing abrasion (100,000 cycles, and further evaluation was conducted for final roughness. Vertical wear (µm was quantified by 3 readings of the real profile between control and brushed surfaces. Data were subjected to analysis of variance, followed by Tukey’s test (p < 0.05. The Pearson correlation test was performed between the surface roughness change and wear (p < 0.05. The mean values of initial/final roughness (Ra, µm/wear (µm were as follows: NX3 (0.078/0.127/23.175; ARC (0.086/0.246/20.263; U100 (0.296/0.589/16.952; and VL2 (0.313/0.512/22.876. Toothbrushing abrasion increased surface roughness and wear of all resin cements tested, although no correlation was found between those variables. Vertical wear was similar among groups; however, it was considered high and may lead to gap formation in indirect restorations.

  3. Performance Enhancement of Abrasive Waterjet Cutting

    Vu Ngoc Pi


    Abrasive Waterjet (AWJ) Machining is a recent non-traditional machining process. This technology is widely used in industry for cutting difficult-to-machine-materials, milling slots, polishing hard materials etc. AWJ machining has many advantages, e.g. it can cut net-shape parts, no heat is generate

  4. Concrete ice abrasion rig and wear measurements

    Shamsutdinova, G.; Rike, P.B.; Hendriks, M.A.N.; Jacobsen, S.


    The wear of concrete material due to ice movement is a challenge for offshore and coastal structures. Concrete surfaces exposed to moving ice are subjected to wear at various rates depending on concrete and ice properties. At NTNU, Department of Structural Engineering, concrete ice abrasion phenomen

  5. Evaluation and Treatment of Perioperative Corneal Abrasions

    Kira L. Segal


    Full Text Available Purpose. To evaluate perioperative risk factors for corneal abrasion (CA and to determine current care for perioperative CA in a tertiary care setting. Methods. Hospital-based, cross-sectional study. In Operating Room and Post-Anesthesia Care Units patients, a comparison of cases and controls was evaluated to elucidate risk factors, time to treatment, and most common treatments prescribed for corneal abrasions. Results. 86 cases of corneal abrasion and 89 controls were identified from the 78,542 surgical procedures performed over 2 years. Statistically significant risk factors were age (P=0.0037, general anesthesia (P<0.001, greater average estimated blood loss (P<0.001, eyes taped during surgery (P<0.001, prone position (P<0.001, trendelenburg position (P<0.001, and supplemental oxygen en route to and in the Post-Anesthesia Care Units (P<0.001. Average time to complaint was 129 minutes. 94% of cases had an inpatient ophthalmology consult, with an average time to consult of 164 minutes. The most common treatment was artificial tears alone (40%, followed by combination treatment of antibiotic ointment and artificial tears (35.3%. Conclusions. Trendelenburg positioning is a novel risk factor for CA. Diagnosis and treatment of perioperative corneal abrasions by an ophthalmologist typically require three hours in the tertiary care setting.

  6. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder...

  7. 9 CFR 311.14 - Abrasions, bruises, abscesses, pus, etc.


    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Abrasions, bruises, abscesses, pus... PARTS § 311.14 Abrasions, bruises, abscesses, pus, etc. All slight, well-limited abrasions on the tongue... a carcass which is badly bruised or which is affected by an abscess, or a suppurating sore shall...

  8. Shrinkage, abrasion, erosion and sorption of clay plasters

    Minke, G.


    Full Text Available At the Buildung Research Institute (FEB, Faculty of Architecture, University of Kassel, Germany, in the last years several hundred tests were made to study the characteristics of different loam mortars in respect of their linear shrinkage, absorption of humidity and their resistance against abrasion and erosion. In order to get data about abrasion and erosion new test methods and special apparatusses were developed. The mortars tested, chosen from the market, showed extremely varying test results.

    En el Laboratorio de Construcciones Experimentales (FEB de la Facultad de Arquitectura, Universidad de Kassel, Alemania, fueron testeados cientos de diferentes pruebas de revoque de barro para estudiar su contracción durante el secado, su absorción de humedad y su resistencia contra abrasión, erosión y absorción. Para recibir datos sobre abrasión y erosión, nuevas aparatos y metodos fueron desarrollados. Los resultados de los revoques comprados en el mercado muestran gran diferencias en los valores.

  9. Effect of carbonitride precipitates on the abrasive wear behaviour of hardfacing alloy

    Yang, Ke; Yu, Shengfu; Li, Yingbin; Li, Chenglin


    Hardfacing alloy of martensitic stainless steel expect higher abradability to be achieved through the addition of nitrogen being provided by the fine scale precipitation of complex carbonitride particles. Niobium and titanium as the most effective carbonitride alloying elements were added in the Fe-Cr13-Mn-N hardfacing alloy to get carbonitride precipitates. Carbonitride was systematically studied by optical microscopy, scanning electronic microscopy and energy spectrum analysis. Abrasive wear resistance of hardfacing alloy in as-welded and heat-treated conditions was tested by using the belt abrasion test apparatus where the samples slide against the abrasive belt. It is found that carbonitride particles in the hardfacing alloy are complex of Cr, Ti and Nb distributing on the grain boundary or matrix of the hardfacing alloy with different number and size in as-welded and heat-treated conditions. A large number of carbonitrides can be precipitated with very fine size (nanoscale) after heat treatment. As a result, the homogeneous distribution of very fine carbonitride particles can significantly improve the grain-abrasion wear-resisting property of the hardfacing alloy, and the mass loss is plastic deformation with minimum depth of grooving by abrasive particles and fine delamination.

  10. Abrasive wear characteristics and mechanisms of Al2O3/PA1010 composite coatings

    JIA Xian; LING Xiaomei


    The abrasive wear characteristics of Al2O3/PA1010 composite coatings on the surface of quenched and low-temperature temper steel 45 were tested on the mmplate abrasive wear testing machine and the same uncoated steel 45 was used as a reference material. Experimental results showed that the abrasive wear resistance of Al2O3//PAl010 composite coatings has a good linear relationship with the volume fraction of Al2O3 particles in Al2O3/PAl010 composite coatings, and the linear correlative coefficient is 0.979. Under the experimental conditions, the size of Al2O3 particles (40.5-161.0 μm) has little influence on the abrasive wear resistance of Al2O3/PA l010 composite coatings. By treating the surface of Al2O3 particles with a suitable bonding agent, the distribution of Al2O3 particles in matrix PAl010 is more homogeneous and the bonding state between Al2O3 particles and matrix PAl010 is better. Therefore, the ml2O3 particles in Al2O3/PA1010 composite coatings make the Al2O3/PAl010 composite coatings have better abrasive wear resistance than PA1010 coatings. The wear resistance of Al2O3/PA 1010 composite coatings is about 45% compared with that of steel 45.

  11. Abrasive Wear Behavior of High Chromium Cast Iron and Hadfield Steel-- A Comparison

    Mehdi Mazar Atabaki; Sajjad Jafari; Hassan Abdollah-pour


    Wear properties of two different crushers used for grinding raw materials of cement industry are compared using pin-on-disk wear test.The wear test was carried out with different loads on a pin.Abrasive wear behavior of two alloys was evaluated by comparing mass loss,wear resistance,microhardness and friction coefficient.The microstructure of the specimens was detected using optical microscope.The results showed that abrasive wear of high chromium cast iron is lower than that of Hadfield steel.Due to the presence of M7C3 carbides on the high chromium cast iron matrix,impact crushers exhibited higher friction coefficient

  12. Abrasion Resistance of as-Cast High-Chromium Cast Iron

    Pokusová Marcela


    Full Text Available High chromium cast irons are widely used as abrasion resistant materials. Their properties and wear resistance depend on carbides and on the nature of the matrix supporting these carbides. The paper presents test results of irons which contain (in wt.% 18-22 Cr and 2-5 C, and is alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve the toughness. Tests showed as-cast irons with mostly austenitic matrix achieved hardness 36-53 HRC but their relative abrasion-resistance was higher than the tool steel STN 19436 heat treated on hardness 60 HRC.

  13. Thermal aspects of ice abrasive water jet technology

    Marko Jerman


    Full Text Available During the last few years, different research groups have been developing systems for the transition of abrasive water jet into ice abrasive water jet. The aim of this new technology is to make the technology cleaner from both practical and ecological points of view. Mineral abrasive is replaced with ice grains that melt away after the machining process, leaving the workpiece uncontaminated. Several different approaches to this technology were studied. Thermal aspects of integrating the ice abrasive water jet technology into commercially available machines were considered. The results and analyses of water temperature measurements on the ice abrasive water jet machine are presented in this article.

  14. Relationship among wear-resistance of three-body abrasion,substructure and property in martensite steels


    The effects of subsurface hardness on wear-resistance of martensitic steel 20Cr, 40CrSi, 60Mn, T8 and T10 in three-body abrasion under static load was investigated. It shows that the characteristic ofthe subsurface hardness distribution and the abrasive wear resistanceis related to the substructure near the worn surface. The substructure of the tested martensite steel has an apparent relationship with thecarbon content and steels with moderate carbon content and hardness exhibit good resistance to abrasive wear. The competition of the work-hardening effect and the temper softening effect, which resulted from deformation and friction heat generating during abrasive wear is considered to be a main reason for the relation among wear-resistance, hardness and substructure. At the test conditions, the wear-resistance of 40CrSi is the best.

  15. Properties, structure and machnining capabilities sintered corundum abrasives

    Cz.J. Niżankowski


    Full Text Available The diversity of sintered corundum abrasives used in both bonded and in the embankment of abrasive tools currently poses substantialproblems for their choice of technology to specific tasks. Therefore performed a comparative study of ownership structures and capacitiesof elected representatives machnining sintered corundum abrasives of different generations, and this is normal sintered alumina,submicrocrystalline alumina sintered and nanocrystalline alumina sintered. Were studied some properties of a set of abrasive particles,physicochemical properties and structural and mechanical and technological properties. The studies used the method of microscopicmeasurement to determine the shape of abrasive particles, the pycnometer to determine the density of abrasive, a spectrometer todetermine the chemical composition of the magnetic analyzer for determining the magnetic fraction, scanning electron microscope toanalysis of abrasive grains and a special position to designate the machining capacity abrasive grains. The results showed a significantincrease in machining capacity sintered corundum abrasives with increasing degree of fragmentation of the crystallites sintered corundum abrasives and distinctive bands in the emerging microchip. The originality of the development provides a comparative summary ofproperties of sintered corundum abrasives of different generations and functions obtained by the author making the change in value indexof machininhcapacity grit from cutting speeds for different generations of sintered corundum.

  16. Computational Fluid Dynamic Simulation of Flow in Abrasive Water Jet Machining

    Venugopal, S.; Sathish, S.; Jothi Prakash, V. M.; Gopalakrishnan, T.


    Abrasive water jet cutting is one of the most recently developed non-traditional manufacturing technologies. In this machining, the abrasives are mixed with suspended liquid to form semi liquid mixture. The general nature of flow through the machining, results in fleeting wear of the nozzle which decrease the cutting performance. The inlet pressure of the abrasive water suspension has main effect on the major destruction characteristics of the inner surface of the nozzle. The aim of the project is to analyze the effect of inlet pressure on wall shear and exit kinetic energy. The analysis could be carried out by changing the taper angle of the nozzle, so as to obtain optimized process parameters for minimum nozzle wear. The two phase flow analysis would be carried by using computational fluid dynamics tool CFX. It is also used to analyze the flow characteristics of abrasive water jet machining on the inner surface of the nozzle. The availability of optimized process parameters of abrasive water jet machining (AWJM) is limited to water and experimental test can be cost prohibitive. In this case, Computational fluid dynamics analysis would provide better results.

  17. Comparative evaluation of enamel abrasivity by toothbrush and velcro: An in vitro scanning electron microscope study

    Saroj Kumar Ojha


    Full Text Available Context: Plaque control has been shown to be pivotal in maintaining the optimal periodontal health. Mechanical plaque control is the most popular option for establishing the optimal oral health. Toothbrushes have been the novel tool for mechanical cleansing. However, the abrasive potential of the toothbrushes on the enamel surface is an area in gray. Aims: The aim of this in vitro study is to evaluate the abrasivity of the toothbrush versus the velcro fasteners. Settings and Design: Forty extracted clinically healthy premolars were grouped in two groups. Group A comprising of teeth that were subjected to toothbrush bristles and group B to velcro fasteners (hook and loop. Materials and Methods: The mounted teeth of both the groups were subjected to abrasion test, and the tooth surfaces were observed for the possible abrasions from the oscillating strokes (toothbrush and frictional contacts (hook and loop velcro and examined under the scanning electron microscope. Results: Comparative assessment of both velcro (hook and loop and toothbrush bristles did not reveal any evidence of abrasion on the tooth specimens. Conclusions: Veclro fasteners are safe and qualitatively at par to the manual toothbrush for their efficacy and efficiency in teeth cleansing

  18. Abrasive Performance of Chromium Carbide Reinforced Ni3Al Matrix Composite Cladding

    LI Shang-ping; LUO He-li; FENG Di; CAO Xu; ZHANG Xi-e


    The Microstructure and room temperature abrasive wear resistance of chromium carbide reinforced NiM3Al matrix composite cladding at different depth on nickel base alloy were investigated. The results showed that there is a great difference in microstructure and wear resistance of the Ni3 Al matrix composite at different depth. Three kinds of tests, designed for different load and abrasive size, were used to understand the wear behaviour of this material. Under all three wear conditions, the abrasion resistance of the composite cladding at the depth of 6 mm, namely NC-M2, was much higher than that of the composite cladding at the depth of 2 mm, namely NC-M1. In addition, the wear-resistant advantage of NC-M2 was more obvious when the size of the abrasive was small. The relative wear resistance of NC-M2 increased from 1.63 times to 2.05 times when the size of the abrasive decreased from 180 μm to 50μm. The mierostructure of the composite cladding showed that the size of chromium carbide particles, which was mainly influenced by cooling rate of melting pool, was a function of distance from the interface between the coating and substrate varied gradually. The chromium carbide particles near the interface were finer than that far from inter-face, which was the main reason for the different wear resistance of the composite cladding at different depth.

  19. The effect of heat treatment on the gouging abrasion resistance of alloy white cast irons

    Are, I. R. S.; Arnold, B. K.


    A series of heat treatments was employed to vary the microstructure of four commercially important alloy white cast irons, the wear resistance of which was then assessed by the ASTM jaw-crusher gouging abrasion test. Compared with the as-cast condition, standard austenitizing treatments produced a substantial increase in hardness, a marked decrease in the retained aus-tenite content in the matrix, and, in general, a significant improvement in gouging abrasion resistance. The gouging abrasion resistance tended to decline with increasing austenitizing tem-perature, although the changes in hardness and retained austenite content varied, depending on alloy composition. Subcritical heat treatment at 500 ° following hardening reduced the retained austenite content to values less than 10 pct, and in three of the alloys it caused a significant fall in both hardness and gouging abrasion resistance. The net result of the heat treatments was the development of optimal gouging abrasion resistance at intermediate levels of retained aus-tenite. The differing responses of the alloys to both high-temperature austenitizing treatments and to subcritical heat treatments at 500 ° were related to the effects of the differing carbon and alloying-element concentrations on changes in the M s temperature and secondary carbide precipitation.




    Full Text Available An internal magnetic abrasive finishing (MAF process was proposed to produce highly finished inner surfaces of workpieces used in critical applications. The process principle and the finishing characteristics of magnetic abrasive finishing of cylindrical pipes using sintered magnetic abrasives are described in this research work. Thesintered magnetic abrasive is a mixture of Al2O3 abrasive and ferromagnetic particles. The Al2O3 based sintered magnetic abrasives have been developed in sintering machine. The surface roughness measurements resulting from finishing experiments demonstrate the effects of the abrasive behavior on the surface modifications. Thesurface finish was analysed in terms of percent improvement in surface finish (PISF. Also surface finish was analysed using Response Surface Methodology (RSM. The obtained maximum PISF was 95% and minimum surface roughness was 0.05 μm Ra. To further study the improvement in surface finish, the surface was microscopically examined using X-Ray Diffraction (XRD.

  1. An Research on Abrasion Resistance of Muzzle Shunt Rail Gun Rail Boronized with Self-protecting B4C Paste

    HUJin-suo; CHENGShu-kang; ZHENGZhen-zhong; MAYuan; LIZhi-yuan


    Based on large numbers of experiments, together with some theoretic support such as equations related to the experiment, thermodynamic principles and so on, one useful and reasonable self-protecting boron formulation is got to reintorce the muzzle shunt rail gun rail. The preliminary friction and abrasion test results show that the formulation is acceptable and the abrasion resistance of the steel rail enhances to some extent after the surface reinforcement.

  2. An Research on Abrasion Resistance of Muzzle Shunt Rail Gun Rail Boronized with Self-protecting B4C Paste

    HU Jin-suo; CHENG Shu-kang; ZHENG Zhen-zhong; MA Yuan; LI Zhi-yuan


    Based on large numbers of experiments, together with some theoretic support such as equations related to the experiment, thermodynamic principles and so on, one useful and reasonable self-protecting boron formulation is got to reinforce the muzzle shunt rail gun rail. The preliminary friction and abrasion test results show that the formulation is acceptable and the abrasion resistance of the steel rail enhances to some extent after the surface reinforcement.

  3. Computational Fluid Dynamics Analysis of Nozzle in Abrasive Water Jet Machining

    Venugopal, S.; Chandresekaran, M.; Muthuraman, V.; Sathish, S.


    Abrasive water jet cutting is one of the most recently developed non-traditional manufacturing technologies. The general nature of flow through the machining, results in rapid wear of the nozzle which decrease the cutting performance. It is well known that the inlet pressure of the abrasive water suspension has main effect on the erosion characteristics of the inner surface of the nozzle. The objective of the project is to analyze the effect of inlet pressure on wall shear and exit kinetic energy. The analysis would be carried out by varying the inlet pressure of the nozzle, so as to obtain optimized process parameters for minimum nozzle wear. The two phase flow analysis would be carried by using computational fluid dynamics tool CFX. The availability of minimized process parameters such as of abrasive water jet machining (AWJM) is limited to water and experimental test can be cost prohibitive.

  4. The Effect of Microstructure on the Abrasion Resistance of Low Alloyed Steels

    Xu, X.


    The thesis attempts to develop advanced high abrasion resistant steels with low hardness in combination with good toughness, processability and low alloying additions. For this purpose, a novel multi-pass dual-indenter (MPDI) scratch test approach has been developed to approach the real continuous a

  5. Air-propelled abrasive grit for postemergence in-row weed control in field corn

    Organic growers need additional tools for weed control. A new technique involving abrasive grit propelled by compressed air was tested in field plots. Grit derived from corn cobs was directed at seedlings of summer annual weeds growing at the bases of corn plants when the corn was at differing early...

  6. A new dimension to conservative dentistry: Air abrasion.

    Hegde, Vivek S; Khatavkar, Roheet A


    Air abrasion dentistry has evolved over a period of time from a new concept of an alternative means of cavity preparation to an essential means of providing a truly conservative preparation for preservation of a maximal sound tooth structure. The development of bonded restorations in combination with air abrasion dentistry provides a truly minimal intervention dentistry. This article reviews the development of air abrasion, its clinical uses, and the essential accessories required for its use.

  7. Abrasion Resistance Comparison between Rotor and Ring Spun Yarn

    YANG Jian-ping; YU Chong-wen


    On the base of literature review and the analysis of yarn properties, yarn structure and some other facts, the abrasion resistance of both rotor spun yarn and ring spun yarns are discussed. The results show that with the same raw material and twist, the rotor spun yarn has lower abrasion resistance than that of ring spun yarn, because of the higher twist employed, the abrasion resistance of rotor spun yarn is higher than that of ring spun yarn.

  8. A new dimension to conservative dentistry: Air abrasion

    Hegde Vivek


    Full Text Available Air abrasion dentistry has evolved over a period of time from a new concept of an alternative means of cavity preparation to an essential means of providing a truly conservative preparation for preservation of a maximal sound tooth structure. The development of bonded restorations in combination with air abrasion dentistry provides a truly minimal intervention dentistry. This article reviews the development of air abrasion, its clinical uses, and the essential accessories required for its use.

  9. Thermal aspects of ice abrasive water jet technology

    Marko Jerman; Henri Orbanić; Mihael Junkar; Andrej Lebar


    During the last few years, different research groups have been developing systems for the transition of abrasive water jet into ice abrasive water jet. The aim of this new technology is to make the technology cleaner from both practical and ecological points of view. Mineral abrasive is replaced with ice grains that melt away after the machining process, leaving the workpiece uncontaminated. Several different approaches to this technology were studied. Thermal aspects of integrating the ice a...

  10. Thermal aspects of ice abrasive water jet technology

    Orbanić, Henri; Lebar, Andrej; Junkar, Mihael; Jerman, Marko


    During the last few years, different research groups have been developing systems for the transition of abrasive water jet into ice abrasive water jet. The aim of this new technology is to make the technology cleaner from both practical and ecological points of view. Mineral abrasive is replaced with ice grains that melt away after the machining process, leaving the workpiece uncontaminated. Several different approaches to this technology were studied. Thermal aspects of integrating the ice a...

  11. Machining human dentin by abrasive water jet drilling.

    Kohorst, Philipp; Tegtmeyer, Sven; Biskup, Christian; Bach, Friedrich-Wilhelm; Stiesch, Meike


    The aim of this experimental in-vitro study was to investigate the machining of human dentin using an abrasive water jet and to evaluate the influence of different abrasives and water pressures on the removal rate. Seventy-two human teeth had been collected after extraction and randomly divided into six homogeneous groups (n=12). The teeth were processed in the area of root dentin with an industrial water jet device. Different abrasives (saccharose, sorbitol, xylitol) and water pressures (15 or 25 MPa) were used in each group. Dimensions of dentin removal were analysed using a stripe projection microscope and both drilling depth as well as volume of abrasion were recorded. Morphological analyses of the dentin cavities were performed using scanning electron microscopy (SEM). Both drilling depth and volume of abrasion were significantly influenced by the abrasive and the water pressure. Depending on these parameters, the drilling depth averaged between 142 and 378 μm; the volume of abrasion averaged between 0.07 and 0.15 mm3. Microscopic images revealed that all cavities are spherical and with clearly defined margins. Slight differences between the abrasives were found with respect to the microroughness of the surface of the cavities. The results indicate that abrasive water jet machining is a promising technique for processing human dentin.

  12. Controlled toothbrush abrasion of softened human enamel.

    Voronets, J; Jaeggi, T; Buergin, W; Lussi, A


    The aim of this in vitro study was to compare toothbrush abrasion of softened enamel after brushing with two (soft and hard) toothbrushes. One hundred and fifty-six human enamel specimens were indented with a Knoop diamond. Salivary pellicle was formed in vitro over a period of 3 h. Erosive lesions were produced by means of 1% citric acid. A force-measuring device allowed a controlled toothbrushing force of 1.5 N. The specimens were brushed either in toothpaste slurry or with toothpaste in artificial saliva for 15 s. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% CI) were recorded in ten treatment groups: (1) soft toothbrush only [28 (17-39) nm]; (2) hard toothbrush only [25 (16-34) nm]; (3) soft toothbrush in Sensodyne MultiCare slurry [46 (27-65) nm]; (4) hard toothbrush in Sensodyne MultiCare slurry [45 (24-66) nm]; (5) soft toothbrush in Colgate sensation white slurry [71 (55-87) nm]; (6) hard toothbrush in Colgate sensation white slurry [85 (60-110) nm]; (7) soft toothbrush with Sensodyne MultiCare [48 (39-57) nm]; (8) hard toothbrush with Sensodyne MultiCare [40 (29-51) nm]; (9) soft toothbrush with Colgate sensation white [51 (37-65) nm]; (10) hard toothbrush with Colgate sensation white [52 (36-68) nm]. Neither soft nor hard toothbrushes produced significantly different toothbrush abrasion of softened human enamel in this model (p > 0.05).

  13. Abrasive water jet: a complementary tool

    Duarte, J. P.


    Full Text Available The abrasive water jet is a powerful cutting tool, whose main advantages lie in the absence of thermal effects and the capability of cutting highly thick materials. Compared with Laser, the abrasive water jet allows the cutting of a larger range of thicknesses and a wider variety of materials such as: ornamental stones, metals, polymers, composites, wood, glass and ceramics. The application of this technology has suffered an extensive growth, with successful applications in varied industrial sectors like the automotive, aerospace, textile, metalworking, ornamental stones, etc. The present communication aims at introducing the abrasive water jet as a complementary tool to laser cutting, presenting its advantages by showing some documented examples of pieces cut for different industries.

    O jacto de água abrasivo é uma poderosa ferramenta de corte, tendo como principais vantagens a ausência de processo térmico e permitir o corte de elevadas espessuras. Comparativamente com o laser o jacto de água abrasivo permite cortar uma maior gama de espessuras, e uma maior diversidade de materiais: rochas ornamentais, metais, polimeros, compósitos, madeiras, vidro e cerâmicos. A aplicação desta tecnologia tem sofrido um crescimento acentuado, existindo aplicações de sucesso nos mais variados sectores industriáis como a indústria automóvel, aeroespacial, têxtil, metalomecânica e rochas ornamentáis. Esta comunição pretende apresentar o corte por jacto de agua abrasivo como uma ferramenta de corte complementar ao corte por laser, apresentando as suas vantagens documentadas através de alguns exemplos de peças executadas para as diferentes indústrias.

  14. [Temperature measurements during abrasive water jet osteotomy].

    Schmolke, S; Pude, F; Kirsch, L; Honl, M; Schwieger, K; Krömer, S


    Working on bone is a major aspect of orthopaedic surgery. Despite its well-known appreciable thermal effects on the edges of the bone cut, the oscillating bone saw blade the oscillating saw remains the standard instrument both for cutting long bones and creating a bed for an endoprosthesis. The application of abrasive water jets offers the possibility of achieving an extremely precise curved cut in bone with no accompanying thermal effect. The thermographically measured absolute temperature increase at the cut edges seen with the water jet was 13 K maximum. The small process forces permit the application in automated handling systems.

  15. Ultrasonic Abrasion: An Alternative for Cavity Preparation

    Áurea Simone Barrôso VIEIRA


    Full Text Available Introduction: Restorative dentistry aims to repair damages caused by caries disease. Along the years, researchers have developed effective and less invasive methods with the goal of preserving the teeth from caries destruction. Therefore, the improvement of scientific knowledge, auxiliary diagnostic systems, dental materials, and new instruments has changed the approaches and treatments in this field. In addition to conservative removal of carious tissue, patient’s comfort has also become a concern in modern dentistry.Purpose: Considering that ultrasonic abrasion has attracted great interest of dental professionals, this article discusses an alternative technique for cavity preparation by literature review, addressing its indications, contra-indications, advantages and limitations compared to the conventional high-speed method.Conclusion: There are not many studies on this subject. The available studies have demonstrated several qualities of the ultrasonic abrasion system, but some aspects remain unclear. Therefore, it is important to highlight that laboratorial and clinical studies in primary/permanent teeth should be conducted to elucidate questionable issues, such as time of cavity preparation, topography, presence of smear layer and microleakage, in order to offer safety to the extensive use of this new technology for both the professional and the patient. In this context, the dentist should always be attentive to innovations referring to minimally invasive techniques.

  16. Diamond-Fluoroplastic Composites for Abrasive Tools

    Adrianova, O. A.; Kirillin, A. D.; Chersky, I. N.


    Composite materials based on polytetrafluoroethylene (PTFE) and natural technical diamond powders from Yakutia diamond deposits are developed. It is shown that the compositions based on PTFE and a technical diamond powder at a content of up to 60 wt.%, due to their good physicomechanical characteristics, low friction coefficient, and good wetting of diamond particles by polymer, make is possible to create abrasive tools for polishing and grinding hard metals and semiprecious and precious stones with high serviceability and operational life combined with a considerable increase in the quality of treated surfaces and operational stability of the tools. It is found that PTFE, being a more elastic and softer matrix than the traditional ones, exhibits a self-sharpening effect of diamond grains upon grinding hard surfaces, when the grains go deep into the elastic matrix, the matrix wears out, and the working part of the tool becomes enriched with the diamond powder. These conclusions are confirmed by electron microscopic investigations. It is shown that the introduction of ultradisperse fillings (up to 2 wt.%) into such compositions allows us to improve the characteristics of abrasive tools considerably, especially for grinding hard semiprecious stones. The physicomechanical and frictional characteristics of the compositions and specific examples of their application in the jewelry industry and in stone working are discussed.

  17. A Finite Element Approach to Modeling Abrasive Wear Modes

    Woldman, M.; Heide, van der E.; Tinga, T.; Masen, M.A.


    Machine components operating in sandy environments will wear because of the abrasive interaction with sand particles. In this work, a method is derived to predict the amount of wear caused by such abrasive action, in order to improve the maintenance concept of the components. A finite element model

  18. Soybean seedlings tolerate abrasion from air-propelled grit

    New tools for controlling weeds would be useful for soybean production in organic systems. Air-propelled abrasive grit is one such tool that performs well for in-row weed control in corn, but crop safety in soybean is unknown. We examined responses to abrasion by corn-cob grit of soybean seedlings a...

  19. Micro-scale abrasion behaviour of electroless Ni-P-SiC coating on aluminium alloy


    Electroless nickel (EN) and electroless nickel composite (ENC) coatings were deposited on aluminium alloy substrate, LM24. The micro abrasion test was conducted to study the wear behaviour of the coatings with the effect of SiC concentration. Microhardness of the coatings was tested also. The wear scars were analysed using optical microscope and scanning electron microscope (SEM). The wear resistance was found to be improved in composite coating that has higher microhardness as compared to pa...

  20. Research and development of blasting abrasive made of steelmaking slag

    TANG Oujing


    This study focuses on the development of a new type of nonmetallic steelmaking slag abrasive.The performance,processing,and application of steelmaking slag as a nonmetallic abrasive are introduced.The chemical composition,hardness,crushing value,and particle gradation of steelmaking slag are analyzed.A processing method for steelmaking slag as a blasting abrasive is suggested and evaluated.Compared with conventional abrasives such as copper ore sand and cast iron shot,processed steelmaking slag exhibits similar performance and can satisfy abrasive technical requirements.The derusting effect provided by steelmaking slag for a ship deck can reach the Sa2.0 level,and its recyclability is higher than that of copper ore sand.The derusting performance of steelmaking slag is similar to that of copper ore,and it can thus be used in repairing ship decks.

  1. Hydro-abrasive erosion: Problems and solutions

    Winkler, K.


    The number of hydro power plants with hydro-abrasive erosion is increasing worldwide. An overall approach is needed to minimize the impact of this phenomenon. Already at the start of the planning phase an evaluation should be done to quantify the erosion and the impact on the operation. For this, the influencing parameters and their impact on the erosion have to be known. The necessary information for the evaluation comprises among others the future design, the particle parameters of the water, which will pass the turbine, and the power plant owner's framework for the future operation like availability or maximum allowable efficiency loss, before an overhaul needs to be done. Based on this evaluation of the erosion, an optimised solution can then be found, by analysing all measures in relation to investments, energy production and maintenance costs as decision parameters. Often a more erosion-resistant design, instead of choosing the turbine design with the highest efficiency, will lead to higher revenue. The paper will discuss the influencing parameters on hydro-abrasive erosion and the problems to acquire this information. There are different optimisation possibilities, which will be shown in different case studies. One key aspect to reduce the erosion and prolong the operation time of the components is to coat all relevant parts. But it is very important that this decision is taken early in the design stage, as the design has to be adapted to the requirements of the coating process. The quality of coatings and their impact on the operation will be discussed in detail in the paper as due to the non-availability of standards many questions arise in projects.

  2. The effect of abrasive blasting on the strength of a joint between dental porcelain and metal base.

    Pietnicki, Krzysztof; Wołowiec, Emilia; Klimek, Leszek


    This paper presents the effect of selected parameters of abrasive blasting on the strength of a joint between dental porcelain and metal base. Experiments were conducted for different grain sizes of abrasive material and different blasting angles, with a constant blasting pressure. InLine dental porcelain was fused on samples of cobalt-chromium alloy following abrasive blasting; they were subsequently subjected to shearing forces on a testing machine. The fractures were observed under an electron scanning microscope in order to determine the character and course of fracturing. Strength tests showed that the grain size of abrasive material was a parameter with the greatest effect on the strength. The best effects were achieved for samples subjected to abrasive blasting with material with grain size of 110 μm. No statistically significant differences were found for the strength of samples worked at different angles. The results of the fractographic examinations have shown that in all the samples, fracturing occurred mainly along the porcelain-metal boundary, with few cases of fracturing through porcelain.

  3. Influence of Utilization of High-Volumes of Class F Fly Ash on the Abrasion Resistance of Concrete

    William PRINCE


    Full Text Available Utilization of large volumes of fly ash in various concrete applications is a becoming a more general practice in an efforts towards using large quantities of fly ash. Around the world, Class C or Class F or both as available have been used in high volumes in cement-based materials. In India, majority of fly generated is of Class F type as per ASTM C 618. Yearly fly ash generation in India is approximately 95 million tonnes. Out of which around 15-20% is utilized in cement production and cement/concrete related activities. In order to increase its percentage utilization, an investigation was carried out to use it in concrete.In this paper, abrasion resistance of high volume fly ash (HVFA concretes made with 35, 45, 55, and 65% of cement replacement was evaluated in terms of its relation with compressive strength. Comparison was made between ordinary Portland cement and fly ash concrete. Test results indicated that abrasion resistance of concrete having cement replacement up to 35 percent was comparable to the normal concrete mix with out fly ash. Beyond 35% cement replacement, fly ash concretes exhibited slightly lower resistance to abrasion relative to non-fly ash concretes. Test results further indicated that abrasion resistance of concrete is closely related with compressive strength, and had a very good correlation between abrasion resistance and compressive strength (R2 value between 0.9018 and 0.9859 depending upon age.

  4. Effect of Bioactive Glass air Abrasion on Shear Bond Strength of Two Adhesive Resins to Decalcified Enamel

    Eshghi, Alireza; Khoroushi, Maryam; Rezvani, Alireza


    Objective: Bioactive glass air abrasion is a conservative technique to remove initial decalcified tissue and caries. This study examined the shear bond strength of composite resin to sound and decalcified enamel air-abraded by bioactive glass (BAG) or alumina using etch-and-rinse and self-etch adhesives. Materials and Methods: Forty-eight permanent molars were root-amputated and sectioned mesiodistally. The obtained 96 specimens were mounted in acrylic resin; the buccal and lingual surfaces remained exposed. A demineralizing solution was used to decalcify half the specimens. Both sound and decalcified specimens were divided into two groups of alumina and bioactive glass air abrasion. In each group, the specimens were subdivided into two subgroups of Clearfil SE Bond or OptiBond FL adhesives (n=12). Composite resin cylinders were bonded on enamel surfaces cured and underwent thermocycling. The specimens were tested for shear bond strength. Data were analyzed using SPSS 16.0 and three-way ANOVA (α=0.05). Similar to the experimental groups, the enamel surface of one specimen underwent SEM evaluation. Results: No significant differences were observed in composite resin bond strength subsequent to alumina or bioactive glass air abrasion preparation techniques (P=0.987). There were no statistically significant differences between the bond strength of etch-and-rinse and self-etch adhesive groups (P=1). Also, decalcified or intact enamel groups had no significant difference (P=0.918). However, SEM analysis showed much less enamel irregularities with BAG air abrasion compared to alumina air abrasion. Conclusion: Under the limitations of this study, preparation of both intact and decalcified enamel surfaces with bioactive glass air abrasion results in similar bond strength of composite resin in comparison with alumina air abrasion using etch-&-rinse or self-etch adhesives. PMID:25628694

  5. Effect of Bioactive Glass air Abrasion on Shear Bond Strength of Two Adhesive Resins to Decalcified Enamel.

    Alireza Eshghi


    Full Text Available Bioactive glass air abrasion is a conservative technique to remove initial decalcified tissue and caries. This study examined the shear bond strength of composite resin to sound and decalcified enamel air-abraded by bioactive glass (BAG or alumina using etch-and-rinse and self-etch adhesives.Forty-eight permanent molars were root-amputated and sectioned mesiodistally. The obtained 96 specimens were mounted in acrylic resin; the buccal and lingual surfaces remained exposed. A demineralizing solution was used to decalcify half the specimens. Both sound and decalcified specimens were divided into two groups of alumina and bioactive glass air abrasion. In each group, the specimens were subdivided into two subgroups of Clearfil SE Bond or OptiBond FL adhesives (n=12. Composite resin cylinders were bonded on enamel surfaces cured and underwent thermocycling. The specimens were tested for shear bond strength. Data were analyzed using SPSS 16.0 and three-way ANOVA (α=0.05. Similar to the experimental groups, the enamel surface of one specimen underwent SEM evaluation.No significant differences were observed in composite resin bond strength subsequent to alumina or bioactive glass air abrasion preparation techniques (P=0.987. There were no statistically significant differences between the bond strength of etch-and-rinse and self-etch adhesive groups (P=1. Also, decalcified or intact enamel groups had no significant difference (P=0.918. However, SEM analysis showed much less enamel irregularities with BAG air abrasion compared to alumina air abrasion.Under the limitations of this study, preparation of both intact and decalcified enamel surfaces with bioactive glass air abrasion results in similar bond strength of composite resin in comparison with alumina air abrasion using etch-&-rinse or self-etch adhesives.

  6. Influence of Shot Peening on Abrasion Wear in Real Conditions of Ni-Cu-Ausferritic Ductile Iron

    Wieczorek A. N.


    Full Text Available The paper presents results of the wear tests of chain wheels made of austempered ductile iron with various content of residual austenite. The aim of this study was to demonstrate the impact of the dynamic surface treatment (shot peening on wear properties of surface layers of the chain wheels tested that were subjected to the action of quartz abrasive. Apart from determining the value of the abrasive wear, examinations of the magnetic phase content in the microstructure were carried out and plots of hardness of the surface layer as a function of the distance from the surface and microstructure of the materials were prepared. Based on the results, the following was found: an increase in the abrasive wear and a reduction in the hardness of the surface layer of chain wheels subjected to shot peening, as well as reduction of susceptibility to negative action of the shot for cast irons with the structure of upper ausferrite.

  7. The impact of the bead width on the properties of the anti-abrasion surfacing weld

    Beczkowski, Robert; Gucwa, Marek; Wróbel, Joanna; Kulawik, Adam


    This work presents the results of research on the anti-abrasion surfacing welds designated to operate under wear conditions. The main purpose of the work was to produce single-layer surface welds by means of semi-automatic hard-facing/surface welding with the use of filler material containing carbide precipitate and with the use of 10mm- and 20mm- wide beads. The samples were subject to visual and penetrant testing and to destructive testing in the form of macro and micro metallographic testing, hardness testing and bend testing with a view to determine the effect which the beads of various widths have on the analysed factors.

  8. Effect of abrasive grit size on wear of manganese-zinc ferrite under three-body abrasion

    Miyoshi, Kazuhisa


    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and deformed layers produced in single-crystal Mn-Zn ferrites under three-body abrasion. The abrasion mechanism of Mn-Zn ferrite changes drastically with the size of abrasive grits. With 15-micron (1000-mesh) SiC grits, abrasion of Mn-Zn ferrite is due principally to brittle fracture; while with 4- and 2-micron (4000- and 6000-mesh) SiC grits, abrasion is due to plastic deformation and fracture. Both microcracking and plastic flow produce polycrystalline states on the wear surfaces of single-crystal Mn-Zn ferrites. Coefficient of wear, total thickness of the deformed layers, and surface roughness of the wear surfaces increase markedly with an increase in abrasive grit size. The total thicknesses of the deformed layers are 3 microns for the ferrite abraded by 15-micron SiC, 0.9 microns for the ferrite abraded by 4-micron SiC, and 0.8 microns for the ferrite abraded by 1-micron SiC.

  9. Abrasive Wear Performance of Aluminium Modified Epoxy-Glass Fiber Composites

    Kamble, Vikram G.; Mishra, Punyapriya; Al Dabbas, Hassan A.; Panda, H. S.; Fernandez, Johnathan Bruce


    For a long time, Aluminum filled epoxies molds have been used in rapid tooling process. These molds are very economical when applied in manufacturing of low volume of plastic parts. To improve the thermal conductivity of the material, the metallic filler material is added to it and the glass fiber improves the wear resistance of the material. These two important parameters establish the life of composites. The present work reports on abrasive wear behavior of Aluminum modified epoxy and glass fiber composite with 5 wt.% and 10 wt.% of aluminum particles. Through pin on disc wear testing machine, we studied the wear behaviors of composites, and all these samples were fabricated by using hand layup process. Epoxy resin was used as matrix material which was reinforced with Glass fiber and Aluminum as filler. The composite with 5 wt.% and 10 wt.% of Al was cast with dimensions 100 × 100 × 6 mm. The specimens were machined to a size of 6 × 6 × 4 mm for abrasive testing. Abrasive tests were carried out for different grit paper sizes, i.e., 150, 320, 600 at different sliding distance, i.e., 20, 40, 60 m at different loads of 5, 10 and 15 N and at constant speed. The weight loss due to wear was calculated along with coefficient of friction. Hardness was found using Rockwell hardness machine. The SEM morphology of the worn out surface wear was analyzed to understand the wear mechanism. Results showed that the addition of Aluminum particles was beneficial for low abrasive conditions.

  10. Refractory, Abrasive, and Other Industrial Minerals Operations - Direct Download

    U.S. Geological Survey, Department of the Interior — This map layer includes refractory, abrasive, and other industrial minerals operations in the United States. The data represent commodities covered by the Minerals...

  11. Anti-abrasive nanocoatings current and future applications


    This book provides an overview of the fabrication methods for anti-abrasive nanocoatings. The connections among fabrication parameters, the characteristics of nanocoatings and the resulting properties (i.e. nanohardness, toughness, wear rate, load-bearing ability, friction coefficient, and scratch resistance) are discussed. Size-affected mechanical properties of nanocoatings are examined, including their uses. Anti-abrasive nanocoatings, including metallic-, ceramic-, and polymeric-based layers, as well as different kinds of nanostructures, such as multi-layered nanocomposites and thin films, are reviewed. * Provides a comprehensive overview of the fabrication methods for anti-abrasive nanocoatings* Discusses the connections among fabrication parameters, the characteristics of nanocoatings and the resulting properties* Reviews advantages and drawbacks of fabrication methods for anti-abrasive nanocoatings and clarifies the place of these nanocoatings in the world of nanotechnology

  12. An Investigation of Different Material on Abrasive Water jet Machine



    Full Text Available Abrasive water jet machine (AWJM is a nontraditional machining process. Abrasive water jet machining is a process of removal of material by impact erosion of high pressure (1500-4000 bar, high velocity of water and entrained high velocity of grit abrasives on a work piece. It’s a non-conventional machining process. At herefirst works on theoretical work after it make some experimental work and then analyses both results. Theoretical MRR found equal to the experimental MRR. In this paper investigation for three different materials like en8,acrylic and aluminum is carried out using Taguchi design of experiment method. Experiments are carried out using L25 Orthogonal array by varying Material traverse speed and abrasive mass flow rate for each material respectively. Anova carried out for identifies significant parameters.

  13. [Dependence of the dentinal abrasion of human teeth on their microhardness].

    Remizov, S M; Pruzhanskiĭ, L Iu


    The dentin resistance against abrasion was studied as related to its microhardness. Sections of 15 intact teeth were investigated (central upper incisors). Water suspensions (40% weight-to weight) of dicalcium phosphate (DCP, FRG; and DKF-1 and DKF-2, USSR) were used as abrasives. Dentin microhardness was measured with a PMT-3 device, and abrasion assessed with profilographic technique. Dentin abrasion was related to its microhardness and to the kind of abrasive used. Dentin abrasion increased as its microhardness decreased. DCF showed minimal abrasive effect, DKF-2 had maximal effect with DKF-1 keeping the intermediate position.

  14. Computed tomography to quantify tooth abrasion

    Kofmehl, Lukas; Schulz, Georg; Deyhle, Hans; Filippi, Andreas; Hotz, Gerhard; Berndt-Dagassan, Dorothea; Kramis, Simon; Beckmann, Felix; Müller, Bert


    Cone-beam computed tomography, also termed digital volume tomography, has become a standard technique in dentistry, allowing for fast 3D jaw imaging including denture at moderate spatial resolution. More detailed X-ray images of restricted volumes for post-mortem studies in dental anthropology are obtained by means of micro computed tomography. The present study evaluates the impact of the pipe smoking wear on teeth morphology comparing the abraded tooth with its contra-lateral counterpart. A set of 60 teeth, loose or anchored in the jaw, from 12 dentitions have been analyzed. After the two contra-lateral teeth were scanned, one dataset has been mirrored before the two datasets were registered using affine and rigid registration algorithms. Rigid registration provides three translational and three rotational parameters to maximize the overlap of two rigid bodies. For the affine registration, three scaling factors are incorporated. Within the present investigation, affine and rigid registrations yield comparable values. The restriction to the six parameters of the rigid registration is not a limitation. The differences in size and shape between the tooth and its contra-lateral counterpart generally exhibit only a few percent in the non-abraded volume, validating that the contralateral tooth is a reasonable approximation to quantify, for example, the volume loss as the result of long-term clay pipe smoking. Therefore, this approach allows quantifying the impact of the pipe abrasion on the internal tooth morphology including root canal, dentin, and enamel volumes.

  15. Study of abrasive wear rate of silicon using n-alcohols

    Danyluk, S.


    The work carried out at the University of Illinois at Chicago for the Flat-Plate Solar Array Project under contract No. 956053 is summarized. The abrasion wear rate of silicon in a number of fluid environments and the parameters that influence the surface mechanical properties of silicon were determined. Three tests were carried out in this study: circular and linear multiple-scratch test, microhardness test and a three-point bend test. The pertinent parameters such as effect of surface orientation, dopant and fluid properties were sorted. A brief review and critique of previous work is presented.

  16. Study on comprehensive properties of duplex austenitic surfacing alloys for impacting abrasion


    In this paper, comprehensive property crack resistance, work hardening and abrasion resistance of a series of double-phases austenitic alloys(FAW) has been studied by means of SEM, TEM and type MD-10 impacting wear test machine. FAW alloys are of middle chromium and low manganese, including Fe-Cr-Mo-C alloy,Fe-Cr-Mn-C alloy and Fe-Cr-Mn-Ni-C alloy, that are designed for working in condition of impacting abrasion resistance hardfacing.Study results show that the work hardening mechanism of FAW alloys are mainly deformation high dislocation density and dynamic carbide aging, the form of wearing is plastic chisel cutting. Adjusting the amount of carbon, nickel, manganese and other elements in austenitic phase area, the FAW alloy could fit different engineering conditions of high impacting, high temperature and so on.

  17. A New Method for Descaling Wool Fibres by Nano Abrasive Calcium Carbonate Particles in Ultrasonic Bath

    Ali rezaghasemi


    Full Text Available Up to now, the most conventional methods for descaling of wool fibre are based on chemical degradation and resin covering of scales or a combination of them. These methods are producing wastewater and can cover physical properties of the fibres beside scales orderly. In this study, a new and clean method is developed on the basis of abrasion effect of calcium carbonate Nano particles (CCNP in an ultrasonic bath. Woolen Samples (fibre and yarn were sonicated with different levels of CCNP. Tensile properties of the yarns, directional friction effect of the fibres and scanning electron microscope images of the fibres were studied. Test results showed that sonicated Nano treatment of woolyarn reduced its tenacity, extension and work of rupture and increased its coefficient of friction. Scanning electron microscope images of fibres and measurement of fibres directional displacement confirmed descaling of Nano abrasive treated wool samples in comparison to the raw wool.

  18. Effect of Pearlite Interlamellar Spacing on Predominant Abrasive Wear Mechanism of Fully Pearlitic Steel

    J.Ahmadi; M.Monirvaghefi; M.Salehi; B.Niroumand


    The aim of this investigation was the determination of the predominant wear mechanism an three-body abrasion of fully pearlitic low ahoy steel. Furthermore. the effect of pearlite interlamellar spacing on wear behavior was investigated, For this purpase, the samples were subjected to the different heat treating to artainthg different interlamellar spacing. Mechanical properties such as hardness, yield strength, tensile strength, elongation, and impact toughness were evaluated. Three body abrasion tests were conducted under ASTM standard condition using a rubber wheel abrasion test apparatus. Abraded surface and wear debris were investigated by light optical microscopy and scanning electron microscopy. The results showed that wear resistance of fully pearlitic steel depended to pearlite interlamellar spacing the and lower spacing has the greater wear realstance, so it may be due to subsurface work hardening and interlamellar spacing and cernentite in fine and/or coarse pearlite, thai influence on surface destruction during wear. Although during wear process the several mechanisms play roles, but study of surface and debris shows that with decreasing interlamellar spacing, the predominant mechanism wear changed front ploughing to cuttthg mode.

  19. Effect of Pearlite Interlamellar Spacing on Predominant Abrasive Wear Mechanism of Fully Pearlitic Steel

    J. Ahmadi; M. Monirvaghefi; M. Salehi; B. Niroumand


    The aim of this investigation was the determination of the predominant wear mechanism on three-body abrasion of fully pearlitic low alloy steel. Furthermore, the effect of pearlite interlamellar spacing on wear behavior was investigated.For this purpose, the samples were subjected to the different heat treating to attaining different interlamellar spacing.Mechanical properties such as hardness, yield strength, tensile strength, elongation, and impact toughness were evaluated.Three body abrasion tests were conducted under ASTM standard condition using a rubber wheel abrasion test apparatus.Abraded surface and wear debris were investigated by light optical microscopy and scanning electron microscopy.The results showed that wear resistance of fully pearlitic steel depended to pearlite interlamellar spacing the and lower spacing has the greater wear resistance, so it may be due to subsurface work hardening and interlamellar spacing and cementite in fine and/or coarse pearlite, that influence on surface destruction during wear. Although during wear process the several mechanisms play roles, but study of surface and debris shows that with decreasing interlamellar spacing, the predominant mechanism wear changed from ploughing to cutting mode.

  20. Wear characteristics of second-phase-reinforced sol-gel corundum abrasives

    Mayer, Joachim [Central Facility for Electron Microscopy (GFE), RWTH Aachen University, 52056 Aachen (Germany)]. E-mail:; Engelhorn, Robert [Laboratory for Machine Tools and Production Engineering (WZL), RWTH Aachen University, 52056 Aachen (Germany); Bot, Rosemarie [Laboratory for Machine Tools and Production Engineering (WZL), RWTH Aachen University, 52056 Aachen (Germany); Weirich, Thomas [Central Facility for Electron Microscopy (GFE), RWTH Aachen University, 52056 Aachen (Germany); Herwartz, Cleo [Central Facility for Electron Microscopy (GFE), RWTH Aachen University, 52056 Aachen (Germany); Klocke, Fritz [Laboratory for Machine Tools and Production Engineering (WZL), RWTH Aachen University, 52056 Aachen (Germany)


    The use of sol-gel technologies makes it possible to manufacture new corundum-based abrasives with superior performance in terms of grinding processes. The aim of the present work is to reveal the detailed wear mechanisms on a nanometre scale and relate them to the particular microstructure of these new materials. A commercial sol-gel corundum (Cubitron 321{sup TM}) was used. In the grinding experiments, wheels consisting of four different mixtures with 0%, 30%, 50% and 100% of sol-gel corundum were used to machine a tool steel (100Cr6V) by plane grinding. Changes to the contact zone were studied after controlled abrasion experiments on hard steel substrates using a pin-on-wheel tribometer, in single grit scratch tests and after tests of resistance to heat shock. Cross-sections through contact areas of a sol-gel grain were prepared using a focused ion beam workstation and investigated using conventional and analytical transmission electron microscopy. The results indicate that the combined effect of controlled propagation of subsurface shear cracks and plastic deformation leads to the formation of flat contact zones. On these contact zones, a nanocrystalline FeO debris layer adheres to the alumina. The results of our investigations were verified in grinding experiments and give insight into the physical reasons of the superior tribological properties of the sol-gel corundum abrasives.

  1. Coupling behavior between adhesive and abrasive wear mechanism of aero-hydraulic spool valves

    Chen Yunxia; Gong Wenjun; Kang Rui


    Leakage due to wear is one of the main failure modes of aero-hydraulic spool valves. This paper established a practical coupling wear model for aero-hydraulic spool valves based on dynamic system modelling theory. Firstly, the experiment for wear mechanism verification proved that adhesive wear and abrasive wear did coexist during the working process of spool valves. Sec-ondly coupling behavior of each wear mechanism was characterized by analyzing actual time-variation of model parameters during wear evolution process. Meanwhile, Archard model and three-body abrasive wear model were utilized for adhesive wear and abrasive wear, respectively. Furthermore, their coupling wear model was established by calculating the actual wear volume. Finally, from the result of formal test, all the required parameters for our model were obtained. The relative error between model prediction and data of pre-test was also presented to verify the accuracy of model, which demonstrated that our model was useful for providing accurate prediction of spool valve’s wear life.

  2. Correlating field and laboratory rates of particle abrasion, Rio Medio, Sangre de Cristo Mountains, New Mexico

    Polito, P. J.; Sklar, L. S.


    as lithologic composition for 100 clasts at each location. To better characterize the size distribution of poorly represented lithologies we also measured every grain we could find of these minority lithologies within a one square meter area on adjacent bar top surfaces. At each sampling site we also measured channel gradient, and bank-full width and depth. We collected gravel samples for laboratory tumbling experiments and larger bedrock blocks from which we extracted cores for the Brazilian tensile splitting strength test. Preliminary results show very rapid fining of the weak sedimentary rocks downstream of the fault, much less rapid fining of the quartzite and a net downstream coarsening of the granitic sediments, which dominate the bed in the downstream end of the study reach. This enigmatic downstream coarsening may be a legacy of Pliestocene glaciation, which is evident in the landscape upstream of the fault. Outburst floods or debris flows from upstream moraines may have delivered large quantities of coarse sediments to downstream reaches, which are now relatively immobile. Despite these complications, the Rio Medio site may yet provide sufficient information to test our proposed method for scaling laboratory particle abrasion rates to the field.

  3. Effect of sodium bicarbonate air abrasive polishing on resistance to sliding during tooth alignment and leveling: An in vitro study

    Jorge C. B. L. Filho


    Full Text Available Objective: The aim of this in vitro study was to evaluate the Resistance to Sliding (RS provided by metallic brackets and 3 types of orthodontic wires (TMA, SS and NiTi, before and after the use of sodium bicarbonate airborne particle abrasion, in an experimental model with 3 non leveled brackets. Materials and Methods: The bicarbonate airborne abrasion was applied perpendicularly to the bracket slots at a distance of 2 mm, for 5 seconds (T2 and 10 seconds (T3 on each bracket slot. In a universal testing machine, the wires were pulled through a set of 3 non leveled brackets at a cross head speed of 50 mm/min for a distance of 10 mm, and static and kinetic friction readings were registered at T1 (no airborne abrasion, T2 and T3. Results: For all tested wires, a significant RS increase between T1 and T3 (P<0.001 was seen. For SS and TMA wires, there was a statistically significant RS increase between T1 and T2 (P<0.001. Between T2 and T3, RS increase was significant for TMA (P<0.001 and NiTiwires (P<0.05. Conclusions: Sodium bicarbonate air abrasive polishing during orthodontic treatment is not recommended, once this procedure promoted a significant RS increase between the metallic brackets and all the three types of wires tested.

  4. Effects of hybrid composition of LCP and glass fibres on abrasive wear of reinforced LLDPE

    S A R Hashmi; Ajay Naik; Navin Chand


    The hybrid of liquid crystalline polymer (LCP) fibres and glass fibres (GF) provide a combination of modulus and toughness to semi-crystalline linear-low-density-polyethylene (LLDPE). LCP and GF fibres reinforced composites were studied using two-body abrasion tester under different applied loads. Two sets of fibre reinforced LLDPE, 10 and 20 vol%, were investigated. The contents of LCP and glass fibres were varied as 25, 50, 75 and 100 vol% of overall volume of fibres in LLDPE. The effect of replacing glass fibre with LCP fibre on wear is reported. Wear loss increased with the applied loads and glass fibre contents in LLDPE. The replacements of glass fibres with LCP fibres improved abrasive wear resistance of composite. The composite containing 20 vol% of glass fibres in LLDPE showed the specific wear rate nearly double to that of LCP fibre reinforced LLDPE. Incorporation of LCP fibre improved wear resistance of glass fibre reinforced LLDPE. Worn surfaces were studied using SEM. Glass fibres were broken in small debris and removed easily whereas LCP fibres yielded to fibrillation during abrasive action. The overall wear rate was governed by the composition and test conditions.

  5. Mechanical and Abrasive Wear Properties of Anodic Oxide Layers Formed on Aluminium

    W.Bensalah; K.Elleuch; M.Feki; M.Wery; H.F.Ayedi


    Aluminium oxide coatings were formed on aluminium substrates in oxalic acid-sulphuric acid bath. Abrasion tests of the obtained anodic layers were carried out on a pin-on-disc machine in accordance with the ISO/DP 825 specifications. The Vickers microhardness, D (HV0.2). and the abrasion weight loss, Wa (mg) were measured. Influence of oxalic acid concentration (Cox), bath temperature (T) and anodic current density (J) on D and Wa has been examined, and the sulphuric acid concentration (Caul) was maintained at 160 g.L-1. It was found that high microhardness and abrasive wear resistance of oxide layers were produced under low temperatures and high current densities with the addition of oxalic acid. The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy (SEM), atomic force microscopy (AFM), optical microscopy and glow-discharge optical emission spectroscopy (GDOES). It was found that the chemistry of the anodizing electrolyte, temperature, and current density are the controlling factors of the mechanical properties of the anodic oxide layer.

  6. Microstructure and Abrasive Wear Performance of Ni-Wc Composite Microwave Clad

    Bansal, Amit; Zafar, Sunny; Sharma, Apurbba Kumar


    In the present work, Ni-WC powder was deposited on mild steel substrate to develop clads through microwave hybrid heating technique. The cladding trials were carried out in an industrial microwave applicator at 1.1 kW for 540 s. The Ni-WC composite clads were characterized for microstructure and abrasive wear performance through combination of x-ray diffraction, electron and optical microscopy, microhardness, and wear tests. Phase analysis of the Ni-WC clad indicated the presence of stable carbides such as WC, W2C, Ni2W4C, and Fe6W6C. The microstructure study of the clad layer revealed the presence of a uniformly distributed interlocked WC-based reinforcement embedded in the Ni-based matrix. The average Vicker's microhardness in the clad layer was observed to be 1028 ± 90 HV, which was approximately three times the microhardness of the substrate. Abrasive wear resistance of the microwave clads was superior to the MS substrate. Abrasion was the main wear mechanism in the Ni-WC clads and the substrate samples. However, the presence of WC-based reinforcement in the composite clads reduced microcutting, resulting in enhanced wear resistance.

  7. Rock Cutting Depth Model Based on Kinetic Energy of Abrasive Waterjet

    Oh, Tae-Min; Cho, Gye-Chun


    Abrasive waterjets are widely used in the fields of civil and mechanical engineering for cutting a great variety of hard materials including rocks, metals, and other materials. Cutting depth is an important index to estimate operating time and cost, but it is very difficult to predict because there are a number of influential variables (e.g., energy, geometry, material, and nozzle system parameters). In this study, the cutting depth is correlated to the maximum kinetic energy expressed in terms of energy (i.e., water pressure, water flow rate, abrasive feed rate, and traverse speed), geometry (i.e., standoff distance), material (i.e., α and β), and nozzle system parameters (i.e., nozzle size, shape, and jet diffusion level). The maximum kinetic energy cutting depth model is verified with experimental test data that are obtained using one type of hard granite specimen for various parameters. The results show a unique curve for a specific rock type in a power function between cutting depth and maximum kinetic energy. The cutting depth model developed here can be very useful for estimating the process time when cutting rock using an abrasive waterjet.

  8. Portable mixed abrasive water jet equipment for rescue in high gas mine shaft

    ZENG Rui; DU Chang-long; XU Rui; ZHAO Jing


    In order to rescue a trapped miner and clean out roadways quickly in a high gas mine shaft after a mining mishap, a special portable cold-cutting equipment is needed, the main technology parameters were calculated according to the advanced cold-cutting technology of high pressure abrasive water jet and the portable mixed abrasive water jet equipment (PAWE) was designed to meet the needs of emergency rescue in high gas mine shafts. Tested the PAWE in a high gas environment, and the result shows that the maximum cutting depth of solid iron pipe is 18 mm and the recoilforce of the sprayer is 28.9 N under the conditions that actual cutting pressure is 29 MPa, starting target distance is 10 mm, cutting speed is 180 mm/min and concentration of abrasive is 32%. The course of the experiment in the high gas environment was smooth and continuous, without any explosion. The PAWE is easy to move and operate, but the nozzle which was worn badly in the sprayer should be changed every 8 minutes.

  9. Effects of different lasers and particle abrasion on surface characteristics of zirconia ceramics.

    Sakineh Arami


    Full Text Available The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP after surface treatment with lasers and airborne-particle abrasion.First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7 and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ and no treatment (controls. Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM.According to ANOVA and Tukey's test, the mean surface roughness (Ra after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers.Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic.

  10. The influence of aluminum and carbon on the abrasion resistance of high manganese steels

    Buckholz, Samuel August

    Abrasive wear testing of lightweight, austenitic Fe-Mn-Al-C cast steel has been performed in accordance with ASTM G65 using a dry sand, rubber wheel, abrasion testing apparatus. Testing was conducted on a series of Fe-30Mn-XAl-YC-1Si-0.5Mo chemistries containing aluminum levels from 2.9 to 9.5 wt.% and carbon levels from 0.9 to 1.83 wt.%. Solution treated materials having an austenitic microstructure produced the highest wear resistance. Wear resistance decreased with higher aluminum, lower carbon, and higher hardness after age hardening. In the solution treated condition the wear rate was a strong function of the aluminum to carbon ratio and the wear rate increased with a parabolic dependence on the Al/C ratio, which ranged from 1.8 to 10.2. Examination of the surface wear scar revealed a mechanism of plowing during abrasion testing and this method of material removal is sensitive to work hardening rate. Work hardening behavior was determined from tensile tests and also decreased with increasing Al/C ratio and after aging hardening. The loss of wear resistance is related to short range ordering of Al and C in the solution treated materials and kappa-carbide precipitation in age hardened materials and both contribute to planar slip and lower work hardening rates. A high carbon tool steel (W1) and a bainitic low alloy steel (SAE 8620) were also tested for comparison. A lightweight steel containing 6.5 wt.% Al and 1.2 wt.% C has wear resistance comparable to within 5% of the bainitic SAE 8620 steel forging currently used for the Bradley Fighting Vehicle track shoe and this cast Fe-Mn-Al-C steel, at equivalent tensile properties, would be 10% lighter.

  11. Minimal alterations on the enamel surface by micro-abrasion: in vitro roughness and wear assessments

    Marcela Charantola Rodrigues


    Full Text Available Objective: To evaluate the in vitro changes on the enamel surface after a micro-abrasion treatment promoted by different products. Material and Methods: Fifty (50 fragments of bovine enamel (15 mm × 5 mm were randomly assigned to five groups (n=10 according to the product utilized: G1 (control= silicone polisher (TDV, G2= 37% phosphoric acid (3M/ESPE + pumice stone (SS White, G3= Micropol (DMC Equipment, G4= Opalustre (Ultradent and G5= Whiteness RM (FGM Dental Products. Roughness and wear were the responsible variables used to analyze these surfaces in four stages: baseline, 60 s and 120 s after the micro-abrasion and after polishing, using a Hommel Tester T1000 device. After the tests, a normal distribution of data was verified, with repeated ANOVA analyses (p≤0.05 which were used to compare each product in different stages. One-way ANOVA and Tukey tests were applied for individual comparisons between the products in each stage (p≤0.05. Results: Means and standard deviations of roughness and wear (µm after all the promoted stages were: G1=7.26(1.81/13.16(2.67, G2=2.02(0.62/37.44(3.33, G3=1.81(0.91/34.93(6.92, G4=1.92(0.29/38.42(0.65 and G5=1.98(0.53/33.45(2.66. At 60 seconds, all products tended to produce less surface roughness with a variable gradual decrease over time. After polishing, there were no statistically significant differences between the groups, except for G1. Independent of the product utilized, the enamel wear occurred after the micro-abrasion. Conclusions: In this in vitro study, enamel micro-abrasion presented itself as a conservative approach, regardless of the type of the paste compound utilized. These products promoted minor roughness alterations and minimal wear. The use of phosphoric acid and pumice stone showed similar results to commercial products for the micro-abrasion with regard to the surface roughness and wear.

  12. Abrasive wear and surface roughness of contemporary dental composite resin.

    Han, Jian-min; Zhang, Hongyu; Choe, Hyo-Sun; Lin, Hong; Zheng, Gang; Hong, Guang


    The purpose of this study was to evaluate the abrasive wear and surface roughness of 20 currently available commercial dental composite resins, including nanofilled, supra-nanofilled, nanohybrid and microhybrid composite resins. The volume loss, maximum vertical loss, surface roughness (R(a)) and surface morphology [Scanning electron microscopy (SEM)] were determined after wear. The inorganic filler content was determined by thermogravimetric analysis. The result showed that the volume loss and vertical loss varied among the materials. The coefficients of determination (R(2)) of wear volume loss and filler content (wt%) was 0.283. SEM micrographs revealed nanofilled composites displayed a relatively uniform wear surfaces with nanoclusters protrusion, while the performance of nanohybrid composites varied. The abrasive wear resistance of contemporary dental composite resins is material-dependent and cannot be deduced from its category, filler loading and composite matrix; The abrasive wear resistance of some flowable composites is comparable to the universal/posterior composite resins.

  13. Comminution of Mica by Cavitation Abrasive Water Jet

    GUO Chu-wen; LIU Lin-sheng; HAN Dong-tai; LI Ai-min; ZHANG Dong-hai


    The comminution of mica with an abrasive water jet is mainly based on three knids of effects, that is, high-speed collision, cavitating effect and shearing effect. Cavitation abrasive water jet was applied for the comminution of mica because cavitation abrasive water jet can make full use of the three effects mentioned above. Besides high speed impacting among particles,cavitation and shearing were also enhanced due to the divergent angle at the outlet of the cavitation nozzle.A JME-200CX transmission electron microscope was used for observing the size distribution of particles.Variance analysis on the experimental results indicates that the effect of cavitation is much more significant than that of collision.The effect of pressure on comminution results becomes less with the decrease of the particle size.

  14. Design and manufacturing of abrasive jet machine for drilling operation

    Mittal Divyansh


    Full Text Available Wide application of Abrasive Jet Machine (AJM is found in machining hard and brittle materials. Machining of brittle materials by AJM is due to brittle fracture and removal of micro chips from the work piece. Embedment of the abrasive particles in the brittle materials results in decrease of machining efficiency. In this paper design and manufacturing of AJM has been presented. Various parts of AJM have been designed using ANSYS 16.2 software. The parts are then manufactured indigenously as per designed parameters. The machine fabricated in this work will be used further for process optimization of AJM parameters for machining of glass and ceramics.

  15. In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing.

    Worschech, Claudia Cia; Rodrigues, José Augusto; Martins, Luis Roberto Marcondes; Ambrosano, Gláucia Maria Bovi


    The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive pastes. A perfilometer was used to measure roughness average (Ra) values of the initial surface roughness and at each 7-day-interval after the beginning of treatment. The bleaching was performed on the surface of the fragments for 1 hour a week, and the surface cleaning treatment for 3 minutes daily. The samples were stored in individual receptacles with artificial saliva. Analysis of variance and the Tukey test revealed significant differences in surface roughness values for G2 and G3, which showed an increase in roughness over time; G1 and G4 showed no significant roughness differences. The bleaching with 35% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with brushing with abrasive dentifrices, there was a significant increase in roughness values.

  16. In vitro evaluation of human dental enamel surface roughness bleached with 35% carbamide peroxide and submitted to abrasive dentifrice brushing

    Worschech Claudia Cia


    Full Text Available The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 35% carbamide peroxide at different times and submitted to different superficial cleaning treatments: G1 - not brushed; G2 - brushed with fluoride abrasive dentifrice; G3 - brushed with a non-fluoride abrasive dentifrice; G4 - brushed without dentifrice. Sixty fragments of human molar teeth with 4 x 4 mm were obtained using a diamond disc. The specimens were polished with sandpaper and abrasive pastes. A perfilometer was used to measure roughness average (Ra values of the initial surface roughness and at each 7-day-interval after the beginning of treatment. The bleaching was performed on the surface of the fragments for 1 hour a week, and the surface cleaning treatment for 3 minutes daily. The samples were stored in individual receptacles with artificial saliva. Analysis of variance and the Tukey test revealed significant differences in surface roughness values for G2 and G3, which showed an increase in roughness over time; G1 and G4 showed no significant roughness differences. The bleaching with 35% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with brushing with abrasive dentifrices, there was a significant increase in roughness values.

  17. System Design of Continuous Feeding Abrasive for Pre-mixed Abrasive Jet and Its Experiment%前混合磨料射流新型连续加砂系统设计与实验

    左伟芹; 卢义玉; 夏彬伟; 刘勇; 葛兆龙


    Pre-mixed abrasive water jets have high capabilities on machining hard materials, such as rock,metal,ceramics etc. However,it is difficult to popularize this technology extensively,due to its inconsecutive abrasive feeding process. To address this problem, a novel abrasive feeding system was put forward in this paper. In this system, a jet pump can add abrasive to two tanks and the tanks are controlled by air-operated valves to supply abrasive to the main pipe line in turn. The results of the separate tests to the jet pump indicated the optimal distance between throat and orifice was 1. 5d1 and the density of the abrasive had very few influence on the entrainment process. The experiment on the whole system with an abrasive jets nozzle of 3mm in diameter also was conducted. Under the operating parameter with the pressure of 20MPa and the abrasive mass concentration of 8% , the test consumed 200kg abrasive with the duration of 30min by switching over between tow tanks 4 times. Hence, It is proved that the novel pre-mixed abrasive water jets system can meet the practical requirement appropriately and has great potential application value.%前混合磨料射流连续加砂难以实现,大大降低了工作效率,制约了该技术的推广运用.针对这一问题,提出在系统中并联两个磨料罐,运用气动闸阀实现磨料罐在加砂、供料两个状态间切换,运用射流泵自行加砂,为前混合磨料射流连续加砂提供新思路.对该系统的主要部件——射流泵进行实验研究,得出吸砂时最优喉嘴距为1.5d1左右,表明引射物的密度对射流泵最优喉嘴距影响较小;用直径为3mm的喷嘴在20MPa压力、8%磨料浓度下进行了30min的实验,共消耗4罐磨料,实现了前混合磨料射流的连续加砂;根据实验条件计算每罐磨料所使用的时间,调整两磨料罐状态切换的间隔时间即可实现不同实验条件下的连续加砂.

  18. Healing effect of Sodium-Sucrose-Octasulfate and EGF on epithelial corneal abrasions in rabbits

    Johansen, Sven; Heegaard, Steffen; Bjerrum, Kirsten Birgitte;


    ophthalmology, Sjögrens syndrome, cornea, abrasion, epidermal growth factor, sodium-sucrose-octasulfate......ophthalmology, Sjögrens syndrome, cornea, abrasion, epidermal growth factor, sodium-sucrose-octasulfate...

  19. Numerical study of agglomerate abrasion in a tumbling mixer

    Thanh Nguyen, [No Value; Willemsz, Tofan; Frijlink, Henderik; Maarschalk, Kees van der Voort


    A numerical simulation using the Discrete Element Method (DEM) was performed to investigate the phenomena concerning the abrasion and breakage of agglomerates in a diffusion powder mixer. Agglomerates were created by defining a single structure of particles with bonds of different strengths using th

  20. Protective effect of green tea on dentin erosion and abrasion

    Melissa Thiemi Kato


    Full Text Available OBJECTIVE: This in situ study evaluated the protective effect of green tea on dentin erosion (ERO and erosion-abrasion (ABR. MATERIAL AND METHODS: Ten volunteers wore intraoral palatal appliances with bovine dentin specimens subjected to ERO or ERO + toothbrushing abrasion performed immediately (ERO+I-ABR or 30 min after erosion (ERO+30-min-ABR. During 2 experimental 5-day crossover phases, the volunteers rinsed with green tea or water (control, 1 min between each erosive (5 min, cola drink and abrasive challenge (30 s, toothbrushing, 4x/day. Dentin wear was measured by profilometry. RESULTS: The green tea reduced the dentin wear significantly for all conditions compared to control. ERO+I-ABR led to significantly higher wear than ERO, but it was not significantly different from ERO+30-min-ABR. ERO+30-min-ABR provoked significant higher wear than ERO, only for the placebo treatment. CONCLUSIONS: From the results of the present study, it may be concluded that green tea reduces the dentin wear under erosive/abrasive conditions.

  1. Abrasive blasting agents: designing studies to evaluate relative risk.

    Hubbs, Ann; Greskevitch, Mark; Kuempel, Eileen; Suarez, Fernando; Toraason, Mark

    Workers exposed to respirable crystalline silica used in abrasive blasting are at increased risk of developing a debilitating and often fatal fibrotic lung disease called silicosis. The National Institute for Occupational Safety and Health (NIOSH) recommends that silica sand be prohibited as abrasive blasting material and that less hazardous materials be used in blasting operations. However, data are needed on the relative risks associated with exposure to abrasive blasting materials other than silica. NIOSH has completed acute studies in rats (Hubbs et al., 2001; Porter et al., 2002). To provide dose-response data applicable to making recommendation for occupational exposure limits, NIOSH has collaborated with the National Toxicology Program (NTP) to design longer term studies with silica substitutes. For risk assessment purposes, selected doses will include concentrations that are relevant to human exposures. Rat lung burdens achieved should be comparable to those estimated in humans with working lifetime exposures, even if this results in "overloading" doses in rats. To quantify both dose and response, retained particle burdens in the lungs and lung-associated lymph nodes will be measured, as well as biochemical and pathological indices of pulmonary response. This design will facilitate assessment of the pulmonary fibrogenic potential of inhaled abrasive blasting agents at occupationally relevant concentrations.

  2. 29 CFR 1926.303 - Abrasive wheels and tools.


    ... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Tools-Hand and Power § 1926.303 Abrasive wheels and tools. (a) Power. All grinding machines shall be supplied with sufficient power to maintain...

  3. Exaggerated abrasion/erosion of human dental enamel surfaces

    Westergaard, J; Moe, D; Pallesen, Ulla


    An atypical, rapidly proceeding abrasion/erosion of the labial enamel surfaces of the maxillary and mandibular incisors and canines in a 27-yr-old man is reported. Ultrastructural examination of a replica of the teeth showed a practically structureless enamel surface both at the initial examinati...

  4. Potential of Air-Propelled Abrasives for Selective Weed Control

    Novel forms of selective weed control are needed by many types of growers, but especially organic growers who are restricted from using synthetic herbicides. Abrasive grit made from corn cobs was expelled from a sand blaster at 517 kPa pressure and aimed at seedlings of common lambsquarters and corn...

  5. Gears castings from ductile iron of improved abrasion wear resistance

    D. Kopyciński


    Full Text Available The aim of this study was to develop an industrial technological process for the manufacturing of castings from alloyed ductile iron characterized by improved resistance to abrasion wear. The outcome of the study was the implementation of developed technology under the industrial conditions of ASPAMET Foundry Plant and start up of production of a wide range of cast gears.

  6. Maintenance and Preservation of Concrete Structures. Report 3. Abrasion-Erosion Resistance of Concrete.


    the length of service that may be expected from a specific concrete. It can be used to determine the relative resistance of a material to the abrasive... CONTRAT 5) ATA CMNTFC IIICU 385 I E.p....s e - F.u 5 IA# RIEIE5, ROOF? *Fpa*RSt ftaE A, --EtI PA.. ,.md II, CRD-C 9. ANA .REdF. IA.. ... 1.(2,. TIB...intended to provide a quantitative measurement of the length of service that may be expected from a specific concrete. Note: Other test methods for

  7. Studies on the Structure and Properties of Multiphase Al2O3 Abrasion-resistant Ceramics

    WU Ren-Ping; YU Yan; RUAN Yu-Zhong


    The Al2O3 abrasion-resistant ceramics is successfully prepared by using waste aluminum sludge as the main raw material with the addition of a little clay, talc and barium carbonate. The crystal structure and microstructure of ceramic are characterized by means of XRD,SEM, etc., and the physical and mechanical properties are also tested. The results show that besides the phase of corundum, a little mullite, Mg-Al spinel and hyalophane phases also exist in the product. These phases are produced via reaction in-situ, which can inhibit the overgrowth of Al2O3grain in grain boundary, and improve the integral property of the material.

  8. Incidence of lameness and abrasions in piglets in identical farrowing pens with four different types of floor

    Nilsson Ebba


    Full Text Available Abstract Background Lameness in piglets is a major animal welfare issue. Floor abrasiveness is a common cause of superficial injury in piglets in farrowing pens. The abrasion achieved may act as a gate for infections, which in turn may induce development of infectious arthritis. In this study, the influence of improvements of the floor quality and of increased ratios of straw in identical farrowing pens was measured. Methods The study was carried out at a herd with four identical farrowing units with solid concrete floor bedded with 1 kg chopped straw per sow and 1 hg per piglet and day. Nothing was changed in the management of the four identical farrowing units, but four experimental groups were created: Group I – control, Group II – the amount of bedding was doubled. The surface of the floor was repaired in two units, Group III – Piglet Floor®, Flowcrete Sweden AB, Perstorp, Sweden and Group IV – Thorocrete SL®, Växa Halland, Sweden. Three farrowing batches were studies in each unit. In total, 93 litters (1,073 piglets were examined for foot and skin lesions until the age of 3 weeks. The occurrence of lameness was registered until weaning at an average age of 4.5 weeks. Twenty seven lame piglets were culled instead of medicinally treated and subjected to necropsy including histopathological and microbiological examinations. Isolates of streptococci, staphylococci and E. coli were tested with respect to antimicrobial resistance. Results Piglet born on the repaired floors had the lowest prevalences of abrasions at carpus. Also the doubled straw ration decreased the abrasions. Skin lesions at carpus decreased significantly in magnitude in all four systems from day 10. At day 3, the sole bruising scores of the control unit were greater than the other three units (p Streptococcus dysgalactiae subsp. equisimilis (60%, Staphylococcus hyicus subsp. hyicus (35% and Escherichia coli (5%. These isolates were sensitive to all antibiotics

  9. Loose abrasive lapping hardness of optical glasses and its interpretation.

    Lambropoulos, J C; Xu, S; Fang, T


    We present an interpretation of the lapping hardness of commercially available optical glasses in terms of a micromechanics model of material removal by subsurface lateral cracking. We analyze data on loose abrasive microgrinding, or lapping at fixed nominal pressure, for many commercially available optical glasses in terms of this model. The Schott and Hoya data on lapping hardness are correlated with the results of such a model. Lapping hardness is a function of the mechanical properties of the glass: The volume removal rate increases approximately linearly with Young's modulus, and it decreases with fracture toughness and (approximately) the square of the Knoop hardness. The microroughness induced by lapping depends on the plastic and elastic properties of the glass, depending on abrasive shape. This is in contrast to deterministic microgrinding (fixed infeed rate), where it is determined from the plastic and fracture properties of the glass. We also show that Preston's coefficient has a similar dependence as lapping hardness on glass mechanical properties, as well as a linear dependence on abrasive size for the case of brittle material removal. These observations lead to the definition of an augmented Preston coefficient during brittle material removal. The augmented Preston coefficient does not depend on glass material properties or abrasive size and thus describes the interaction of the glass surface with the coolant-immersed abrasive grain and the backing plate. Numerical simulations of indentation are used to locate the origin of subsurface cracks and the distribution of residual surface and subsurface stresses, known to cause surface (radial) and subsurface (median, lateral) cracks.

  10. Application of laser scanning microscopy in the development of highly abrasion-resistant glazes for fast-fired hard paste porcelain

    Pham-Gia, K.; Moertel, H. [Erlangen-Nuernberg Univ., Erlangen (Germany). Lehrstuhl fuer Glas und Keramik; Melchner, R.; Voit, K. [Porzellanfabrik Christian Seltmann GmbH, Weiden (Germany)


    To strengthen the competitiveness of porcelain manufacturers in national and international markets with their ever increasing quality requirements, the research presented was aimed at developing highly abrasion-resistant glazes for fast-fired hard paste porcelain. By increasing the degree of cross-linking in the glass structure, it was possible to improve the mechanical abrasion resistance of porcelain glazes. Uniform and defect-free glaze application is particularly important for achieving this improvement. To determine the abrasion resistance of the glazes, a new testing method was developed in which the glaze surface is analysed topographically with a laser scanning microscope before and after defined sand-blasting and the roughness parameters compared. The glaze development work could be minimized with the help of fractional factorial statistical test planning according to the Taguchi method. (orig.)

  11. In vitro comparative bond strength of contemporary self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion.

    Blatz, Markus B; Phark, Jin-Ho; Ozer, Fusun; Mante, Francis K; Saleh, Najeed; Bergler, Michael; Sadan, Avishai


    This study compared shear bond strengths of six self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. One hundred twenty zirconia samples were air-abraded (group SB; n = 60) or left untreated (group NO). Composite cylinders were bonded to the zirconia samples with either BisCem (BC), Maxcem (MC), G-Cem (GC), RelyX Unicem Clicker (RUC), RelyX Unicem Applicator (RUA), or Clearfil SA Cement (CSA). Shear bond strength was tested after thermocycling, and data were analyzed with analysis of variance and Holm-Sidak pairwise comparisons. Without abrasion, RUA (8.0 MPa), GC (7.9 MPa), and CSA (7.6 MPa) revealed significantly higher bond strengths than the other cements. Air-particle abrasion increased bond strengths for all test cements (p MDP/4-META) were superior to other compositions.

  12. Etude de la degradation des refractaires aluminosiliceux par abrasion, chocs thermiques et corrosion par l'aluminium: Correlation et interaction des mecanismes

    Ntakaburimvo, Nicodeme

    Aluminosilicate refractories used for melting and holding furnaces on which the present work was focused are submitted to mechanical abuse such as abrasion, mechanical impact and erosion, on one hand; and to chemical degradation by corrosion, as well as to thermal stresses, mostly due to thermal shocks; on the other hand. This thesis is focused on four main objectives. The first one is related to the designing of an experimental set-up allowing abrasion testing of refractories. The second deals with the separate study of the deterioration of aluminosilicate refractories by abrasion, thermal shock and corrosion. The third is the correlation between these three mechanisms while the fourth is related to the interaction between thermal shock and corrosion. One of the contributions of this thesis is the realisation of the above mentioned experimental set-up, which permits to carry out refractories abrasion testing, as well as at room and high temperature, in the absence or in the presence of molten metal. The fact of testing refractory resistance when it is submitted separately and simultaneously to the action of dynamic corrosion, erosion and abrasion leads to the studying of the influence of each of these three mechanisms on the other. One of the characteristics of the designed set-up is the fact that it allows to adjust the seventy testing conditions according to the mechanical resistance of the test material. The other important point is related to the fact the abrasion tests were carried out in such manner to permit degradation quantification, otherwise than by the traditional method of loss of weight measurement; particularly by measuring the wear depth and the residual material properties, such as the rupture force and the strength. A perfect correlation was observed between the wear depth and the loss of weight, both being negatively correlated with the residual rupture force. The abrasion resistance was found to be globally positively correlated with the

  13. Research on the abrasive wear resistance of YDCrMoV coating produced by CO2 shielded flux-cored wire surfacing


    Caterpillar construction machines play an important part in many fields such as hydraulic and electric engineering, the construction of highway, for its particular of structure. The walking system of caterpillar construction machines is always under the condition of three-body abrasive wear. The abrasive wear of walking system is very severe, which always results in damages of components or structures of walking system of caterpillar construction machines. It is very important to repair the walking system by cladding technique. The abrasive wear properties of four kinds coatings produced by the shielded flux-cored wire surfacing for the repair of the damaged components of walking system of caterpillar construction machines have been studied experimentally on an MLS-23 type wet sand rubber wheel abrasive tester. The surfaces morphologies of the abrasively worn specimens and their microstructures are investigated by transmitting electron microscopy (TEM) after wear testing. Results show that the wear mechanism of cladding metals of the flux-cored wire No.1 and the No.2 is micro-cutting while that of the No.3 and the No.4 is micro-ploughing. The four kinds of flux-cored wire coatings present great potential applications for the repairing of caterpillar construction machines in the Three Gorges Engineering.

  14. Abrasive Wear Study of NiCrFeSiB Flame Sprayed Coating

    Sharma, Satpal


    In the present study, abrasive wear behavior of NiCrFeSiB alloy coating on carbon steel was investigated. The NiCrFeSiB coating powder was deposited by flame spraying process. The microstructure, porosity and hardness of the coatings were evaluated. Elemental mapping was carried out in order to study the distribution of various elements in the coating. The abrasive wear behavior of these coatings was investigated under three normal loads (5, 10 and 15 N) and two abrasive grit sizes (120 and 320 grit). The abrasive wear rate was found to increase with the increase of load and abrasive size. The abrasive wear resistance of coating was found to be 2-3 times as compared to the substrate. Analysis of the scanning electron microscope images revealed cutting and plowing as the material removal mechanisms in these coatings under abrasive wear conditions used in this investigation.




    Full Text Available In many applications, when a precise non-contact assessment of an abrasive tools’ surface is required, alternative measurement methods are often used. Their use offers numerous advantages (referential method as they introduce new qualities into routinely realized measurements. Over the past few years there has been a dynamic increase in the interest for using new types of classical confocal microscopy. These new types are often defined as 3D laser microscopy. This paper presents select aspects of one such method’s application – confocal laser scanning microscopy – for diagnostic analysis of abrasive tools. In addition this paper also looks at the basis for operation, the origins and the development of this measurement technique.The experimental part of this paper presents the select results of tests carried out on grinding wheel active surfaces with sintered microcrystalline corundum grains SG™ bound with glass-crystalline bond. The 3D laser measuring microscopes LEXT OLS3100 and LEXT OLS4000 by Olympus were used in the experiments. Analysis of the obtained measurement data was carried out in dedicated OLS 5.0.9 and OLS4100 2.1 programs, supported by specialist TalyMap Platinum 5.0 software. The realized experiments confirmed the possibility of using the offered measurement method. This concerns both the assessment of grinding wheel active surfaces and their defects, as well as the internal structures of the tools (grain-bond connections. The method presented is an interesting alternative to the typical methods used in the diagnostics of abrasive tools.

  16. Optimization of Abrasive Water Jet Cutting of Ductile Materials

    Asif IQBAL; Naeem U DAR; Ghulam HUSSAIN


    Full factorial design of experiments was developed in order to investigate the effects of jet pressure, abrasive mixing rate, cutting feed, and plate thickness upon three response variables, surface finish of cutting wear zone, percentage proportion of striation free area, and maximum width of cut. The set of sixteen experiments was performed on each of the following two ductile materials: AISI 4340 (high strength low alloy steel, hardened to 49HRc) and Aluminum 2219. Analysis of Variance (ANOVA) was performed on experimental data in order to determine the significance of effects of different parameters on the performance measures. It was found that cutting feed and thickness were highly influential parameters, while abrasive mixing rate is influential upon surface roughness only. Strong interaction was found between jet pressure and workpiece material.Multi-criteria numerical optimization was performed in order to simultaneously maximize/minimize different combinations of performance measures.

  17. Nanometric Finishing on Biomedical Implants by Abrasive Flow Finishing

    Subramanian, Kavithaa Thirumalai; Balashanmugam, Natchimuthu; Shashi Kumar, Panaghra Veeraiah


    Abrasive flow finishing (AFF) is a non-conventional finishing technique that offers better accuracy, efficiency, consistency, economy in finishing of complex/difficult to machine materials/components and provides the possibility of effective automation as aspired by the manufacturing sector. The present study describes the finishing of a hip joint made of ASTM grade Co-Cr alloy by Abrasive Flow Machining (AFM) process. The major input parameters of the AFF process were optimized for achieving nanometric finishing of the component. The roughness average (Ra) values were recorded during experimentation using surface roughness tester and the results are discussed in detail. The surface finished hip joints were characterized using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and residual stress analysis using X-Ray Diffraction (XRD). The discussion lays emphasis on the significance, efficacy and versatile nature of the AFF process in finishing of bio-medical implants.

  18. Abrasions and lameness in piglets born in different farrowing systems with different types of floor

    Mattsson Sigbrit


    Full Text Available Abstract Background The quality of the floor is essential to the welfare of piglets as abrasions often are recorded in newborn piglets, and such lesions may lead to lameness. Apart from animal suffering, lameness contributes to losses in form of dead piglets, decreased growth, and increased use of antibiotics and manual labour. Methods In a herd with three different farrowing systems, 37 litters (390 piglets were studied until the age of 3 weeks with respect to presence of skin wounds and abrasions. Lameness was registered until the age of 7 weeks. Eight lame piglets were sacrificed before medical treatment and subjected to necropsy including histopathological and microbiological examinations. Isolates of streptococci, staphylococci and E. coli were tested with respect to antimicrobial resistance. Mastitis was observed in ten sows. Results The most severe abrasions at carpus and soles were seen in the system with a new solid concrete floor with a slatted floor over the dunging area. The lowest magnitude was observed in the deep litter system with peat. Sole bruising was more common in the systems with concrete floor compared to the deep litter system with peat, and the differce in prevalence was significant at all examination days. The lesions decreased with time and about 75% of the treatments for lameness were performed during the first three weeks of life. The overall prevalence of lameness was highest in the system with new solid concrete floor with a slatted floor over the dunging area (9.4% followed by the old solid concrete floor (7.5%. A lower (p Conclusion There were large differences in the prevalence of abrasions and lameness between the floor types. The deep litter system with peat provided a soft and good floor for piglets. The overall prevalence of lameness was only diagnosed in every fourth litter in that system compared to in every second litter in the systems with concrete floor. In contrast, the incidence of mastitis in the

  19. Microstructure formation and properties of abrasion resistant cast steel

    S. Parzych; Krawczyk, J.


    The so-called adamitic cast steels are characterised by a high abrasion resistance. These cast steels are of a pearlitic matrix with uniformly distributed hypereutectoid cementite precipitates. Apart from hypereutectoid cementite very often transformed ledeburite also occurs in the microstructure of these cast steels. Such cast steels contain chromium (app. 1 %) and nickel (app. 0.5 %) as alloy additions and sometimes their silicon content is increased. The presence of molybdenum is also perm...

  20. Kevlar Properties Investigation High Speed Abrasion Resistance


    This technical report has been reviewed and is approved for publication. WILLIAM R. PINNELL EDWIN R. SCHULTZ, Chief Project Engineer Crew Escape...Mr. W. R. Pinnell acting as Project Engineer. Mr. NOJ J7.Ab % vwas the FR. Associate Director responsible for the overall programY Iffajority of...ft-lb. In all cases , a fresh abrad- ing surface was used only for each test. In most cases both surfaces of the abrading specimen were used. In the

  1. Surface characterization of current composites after toothbrush abrasion.

    Takahashi, Rena; Jin, Jian; Nikaido, Toru; Tagami, Junji; Hickel, Reinhard; Kunzelmann, Karl-Heinz


    The present study was designed to evaluate the surface roughness and the gloss of current composites before and after toothbrush abrasion. We assessed forty dimensionally standardized composite specimens (n=8/group) from five composites: two nanohybrids (i. e., IPS Empress Direct Enamel and IPS Empress Direct Dentin), two microhybrids (i. e., Clearfil AP-X and Filtek Z250) and one organically modified ceramics (Admira). All of the specimens were polished with 4000-grid silicon carbide papers. Surface roughness was measured with a profilometer and gloss was measured with a glossmeter before and after powered toothbrush abrasion with a 1:1 slurry (dentifrice/tap water) at 12,000 strokes in a toothbrush simulator. There was a significant increase in the surface roughness and a reduction in gloss after toothbrush abrasion in all of the composites except Clearfil AP-X (p<0.05). Simple regression analysis showed that there was not an association between the surface roughness and the gloss (R(2)=0.191, p<0.001).

  2. Correlation Between Particle Velocities and Conditions of Abrasive Waterjet Formation

    Chen, Wei-Long


    The velocities of water and abrasive particles in abrasive waterjet(AWJ) were measured by the use of Laser Transit Anemometer(LTA). A setup for the velocity measurement was constructed and a statistical technique was used to improve the accuracy of the velocity determination. A comparison of the magnitude of velocities determined by LTA, Piezoelectric Force Transducer and Schlieren Photograph clearly indicates the feasibility of the use of LTA. The velocities of water and particles were measured for different diameters of water and slurry nozzles, abrasive mass flow rates and particle sizes. The performed experiments enabled us to evaluate the effects of conditions of jet formation on the particles velocities. An empirical equation for the prediction of particles velocities was constructed by the use of obtained results. The coefficient of correlation between experimental and computed results is equal to 0.93. The acquired information can be used to select the operational parameters in AWJ cutting. The obtained results also provide information on the acceleration mechanism of entrained particles, which may be used to improve the design of slurry nozzle.

  3. Machining of Aircraft Titanium with Abrasive-Waterjets for Fatigue Critical Applications

    Liu, H. T.; Hovanski, Yuri; Dahl, Michael E.


    Laboratory tests were conducted to determine the fatigue performance of abrasive-waterjet- (AWJ-) machined aircraft titanium. Dog-bone specimens machined with AWJs were prepared and tested with and without sanding and dry-grit blasting with Al2O3 as secondary processes. The secondary processes were applied to remove the visual appearance of AWJ-generated striations and to clean up the garnet embedment. The fatigue performance of AWJ-machined specimens was compared with baseline specimens machined with CNC milling. Fatigue test results of the titanium specimens not only confirmed our previous findings in aluminum dog-bone specimens but in comparison also further enhanced the fatigue performance of the titanium. In addition, titanium is known to be difficult to cut, particularly for thick parts, however AWJs cut the material 34% faster han stainless steel. AWJ cutting and dry-grit blasting are shown to be a preferred ombination for processing aircraft titanium that is fatigue critical.

  4. Hydro-abrasive erosion of hydraulic turbines caused by sediment - a century of research and development

    Felix, D.; Albayrak, I.; Abgottspon, A.; Boes, R. M.


    Hydro-abrasive erosion of hydraulic turbines is an economically important issue due to maintenance costs and production losses, in particular at high- and medium-head run-of- river hydropower plants (HPPs) on sediment laden rivers. In this paper, research and development in this field over the last century are reviewed. Facilities for sediment exclusion, typically sand traps, as well as turbine design and materials have been improved considerably. Since the 1980s, hard-coatings have been applied on Francis and Pelton turbine parts of erosion-prone HPPs and became state-of-the-art. These measures have led to increased times between overhauls and smaller efficiency reductions. Analytical, laboratory and field investigations have contributed to a better processes understanding and quantification of sediment-related effects on turbines. More recently, progress has been made in numerical modelling of turbine erosion. To calibrate, validate and further develop prediction models, more measurements from both physical model tests in laboratories and real-scale data from HPPs are required. Significant improvements to mitigate hydro-abrasive erosion have been achieved so far and development is ongoing. A good collaboration between turbine manufacturers, HPP operators, measuring equipment suppliers, engineering consultants, and research institutes is required. This contributes to the energy- and cost-efficient use of the worldwide hydropower potential.

  5. Influence of Zn (II) ion on abrasive-free polishing of hard disk substrate

    Lei, Hong, E-mail:; Zhao, Rong, E-mail:; Chen, Ruling, E-mail:


    With higher requirement setting for hard disk substrate to minimize roughness and defects of the polished surface, abrasive-free polishing (AFP) of hard disk substrate has been put forward in this paper. The effect of Zn (II) ion on the AFP of hard disk substrate in the H{sub 2}O{sub 2} based slurry was investigated by AFP tests. The results indicate that the material removal rate of hard disk substrate polished in slurry with Zn (II) ion is obviously higher than that without Zn (II) ion. And surface polished by slurry containing Zn (II) ion exhibits lower surface roughness and fewer nano-asperity peaks than that without Zn (II) ion. Furthermore, the acting mechanism of Zn (II) ion in AFP of hard disk substrate was analyzed. X-ray photoelectron spectroscopy analysis shows that metal Zn appears on the polished surface, implying the tribochemistry reaction occurs during AFP. The electrochemical reaction between metal Zn and oxide film Ni{sub 2}O{sub 3} on the surface of hard disk substrate during AFP can promote the chemical effect in AFP and lead to the increasing of material removal rate. - Highlights: • Zn (II) ion improves surface quality in abrasive-free polishing (AFP). • The removal rate increases with the increasing of Zn (II) ion content. • Tribo-chemistry reaction exists during AFP. • Zn (II) ion accelerates the electrochemistry reaction during AFP.

  6. The importance of extractives and abrasives in wood materials on the wearing of cutting tools

    Wayan Darmawan


    Full Text Available For many wood cutting processes, the interest of high-speed tool steels and tungsten carbides remains very important because of their good tool edge accuracy and easy grinding. The wear of high-speed steel and tungsten carbide is an important economic parameter. Wood extractives and silica have a potential adverse effect on tool wear. Rapid chemical wearing due to corrosion and mechanical wearing has been attributed to the presence of extractives and silica in wood and wood composites. This paper presents the wear characteristics of SKH51 high-speed steel and K10 tungsten carbide caused by extractive and abrasive materials present in the lesser-known Tapi-Tapi wood and wood composites of wood cement board, particleboard, MDF, and oriented strand board (OSB. Experimental results showed that wearing of the cutting tools tested was determined by extractives and silica contained in the wood and wood composites. Wood cement board, which is high in silica content, caused severe damage to the cutting edge of the high-speed steel. A corrosion/oxidation mechanism was found to contribute to the wear of SKH51 and K10 when cutting the Tapi-Tapi wood, MDF, particleboard, wood cement board, and OSB. The silica and extractives determined the abrasion and corrosion wear mechanism to a varying degree.

  7. Development and validation of an alternative disturbed skin model by mechanical abrasion to study drug penetration.

    Schlupp, P; Weber, M; Schmidts, T; Geiger, K; Runkel, F


    Pharmaceuticals and cosmetics for dermal application are usually tested on healthy skin, although the primary permeation barrier, the stratum corneum, is often impaired by skin diseases or small skin lesions, especially on the hands. These skin conditions can considerably influence the permeation of chemicals and drugs. Furthermore, risk assessment for example of nanoparticles should be performed under various skin conditions to reflect the true circumstances. Therefore, an alternative and reproducible method for a high throughput of skin samples with impaired skin barrier was developed and verified by skin permeation studies (25 h) of caffeine, sorbic acid and testosterone compared to healthy (untreated) and tape-stripped skin. Skin barrier disruption was controlled by TEWL measurement. Skin permeation of the three substances was increased in tape-stripped and abraded skin compared to untreated skin due to the reduced barrier integrity. Enhancement of drug uptake was highest for the most hydrophilic substance, caffeine, followed by sorbic acid and lipophilic testosterone. No significant difference in drug uptake studies was observed between the new abrasion method with an aluminum-coated sponge and the tape-stripping method. The obtained results demonstrate that this abrasion method is an alternative way to achieve a disturbed skin barrier for drug and chemical uptake studies.

  8. Effect of Heat Treatment of Wild Cherry Wood on Abrasion Resistance and Withdrawal Capacity of Screws

    Ayhan Aytin


    Full Text Available In its wise use, many properties of wood are important. Among these properties, wood abrasion resistance (AR and withdrawal capacity of screws (WCS are deemed to be relatively signifi cant. It is well know that heat treatment changes the resistance features of wooden materials by changing the structural characteristics of wood. Within the scope of this study, the effects were investigated of the temperature and duration of heat treatment of Wild Cherry (Cerasus avium (L. Monench on its AR and its WCS in the radial direction and tangential direction. The test results indicated that weight loss (WL and thickness reduction (TR remained almost the same in the radial direction specimen, but there was significant TR in the tangential direction specimen. As a result of these changes, the abrasion effect of the S-42 abrader diminished based on the increase in the number of cycles. However, in both the radial and tangential direction, the WCS decreased to a significantly greater extent in the heat-treated specimens than in the control specimens.

  9. Analysis of abrasive wear behavior of PTFE composite using Taguchi’s technique

    Yusuf Şahin


    Full Text Available Polymeric composites are widely used for structural, aerospace, and automobile sectors due to their good combination of high specific strength and specific modulus. These two main characteristics make these materials attractive, compared to conventional materials like metal or alloy ones. Some of their typical benefits include easy processing, corrosion resistance, low friction, and damping of noise and vibrations. Wear behavior of Polytetrafluoroethylenes (PTFE and its composites including glass-filled composites and carbon-filled composites are investigated using a pin-on-disc configuration. A plan of experiments in terms of Taguchi technique is carried out to acquire data in controlled way. An orthogonal array (L9 and the analysis of variance are employed to investigate the influence of process parameters on the wear of these composites. Volume loss increased with abrasive size, load, and distance. Furthermore, specific wear rate decreased with increasing grit size, load, sliding distance, whereas, slightly with compressive strength. Optimal process parameters, which minimize the volume loss, were the factor combinations of L1, G3, D1, and C3. Confirmation experiments were conducted to verify the optimal testing parameters. It was found that in terms of volume loss, there was a good agreement between the estimated and the experimental value of S/N ratio with an error of 1.604%. Moreover, abrasive size, load, and sliding distance exerted a great effect on the specific wear rate, at 51.14, 27.77, and 14.70%, respectively.

  10. Effects of process parameters on mechanical properties of abrasive-assisted electroformed nickel

    Ren Jianhua


    Full Text Available A cathode mandrel with translational and rotational motion, which was supposed to obtain uniform friction effect on surface, was employed in abrasive-assisted electroforming for revolving parts with complex profile. The effects of current density, translational speed and rotational speed on the deposit properties were studied by orthogonal test. The tensile strength, elongation and micro hardness value were measured to find out how the factors affected the properties. The optimized results show that changes of current density affect the tensile strength of nickel layer most, while translational speed has the most remarkable influences on both elongation and micro hardness. The low rotational speed affects the properties least. In this experiment, a smooth nickel layer with tensile strength 581 MPa, elongation 17% and micro hardness 248HV is obtained by the orthogonal test.

  11. Effects of process parameters on mechanical properties of abrasive-assisted electroformed nickel

    Ren Jianhua; Zhu Zengwei; Zhu Di


    A cathode mandrel with translational and rotational motion, which was supposed to obtain uniform friction effect on surface, was employed in abrasive-assisted electroforming for revolving parts with complex profile. The effects of current density, translational speed and rotational speed on the deposit properties were studied by orthogonal test. The tensile strength, elongation and micro hardness value were measured to find out how the factors affected the properties. The optimized results show that changes of current density affect the tensile strength of nickel layer most, while translational speed has the most remarkable influences on both elonga-tion and micro hardness. The low rotational speed affects the properties least. In this experiment, a smooth nickel layer with tensile strength 581 MPa, elongation 17%and micro hardness 248HV is obtained by the orthogonal test.

  12. The structure, properties and a resistance to abrasive wear of railway sections of steel with a different pearlite morphology

    Aniolek, K [Institute of Materials Science, University of Silesia, Bankowa 12, 40-007 Katowice (Poland); Herian, J, E-mail: [Department of Materials Technology, Silesian University of Technology, Krasinskiego 8, 40-019 Katowice (Poland)


    The article presents the characteristics of pearlite rail steels used in the construction of railways. The article discusses the influence of isothermal annealing process parameters on the pearlite morphology and properties of the R260 steel. The pearlite structure with a diverse pearlite morphology was obtained in the physical modeling of the isothermal annealing on the 3800 Gleeble Simulator. After the heat treatment, the existence of the pearlite microstructure with pearlite colonies was identified. They were smaller in relation to colonies after the hot rolling process. It was shown that the reduction of isothermal holding temperature influences the decrease of the interlamellar distance in the pearlite steel. On the basis of the received results, the dependences between the resistance to the abrasive wear and the pearlite morphology for operational conditions occurring in the switches were estimated. The resistance to the abrasive wear tests were conducted for steel with a different morphology of pearlite on the Amsler stand in conditions of rolling- sliding frictions. The resistance to the abrasive wear of R260 steel with a different pearlite morphology increases, when the interlamellar distance in cementite decreases and decreases as the load and slip increase.

  13. Improvement in Abrasion Wear Resistance and Microstructural Changes with Deep Cryogenic Treatment of Austempered Ductile Cast Iron (ADI)

    Šolić, Sanja; Godec, Matjaž; Schauperl, Zdravko; Donik, Črtomir


    The application of a deep cryogenic treatment during the heat-treatment processes for different types of steels has demonstrated a significant influence on their mechanical and tribological properties. A great deal of research was conducted on steels, as well as on other kinds of materials, such as hard metal, gray cast iron, aluminum, aluminum alloys, etc., but not on austempered ductile iron (ADI). In this research the influence of a deep cryogenic treatment on the microstructure and abrasive wear resistance of austempered ductile iron was investigated. The ductile cast iron was austempered at the upper ausferritic temperature, deep cryogenically treated, and afterwards tempered at two different temperatures. The abrasion wear resistance was tested using the standard ASTM G65 method. The microstructure was characterized using optical microscopy, field-emission scanning electron microscopy, electron back-scattered diffraction, and X-ray diffraction in order to define the microstructural changes that influenced the properties of the ADI. The obtained results show that the deep cryogenic treatment, in combination with different tempering temperatures, affects the matrix microstructure of the austempered ductile iron, which leads to an increase in both the abrasion wear resistance and the hardness.

  14. Assessment of variations in wear test methodology.

    Gouvêa, Cresus V D; Weig, Karin; Filho, Thales R M; Barros, Renata N


    The properties of composite resin for dental fillings were improved by development, but its weakness continues to be its wear strength. Several tests have been proposed to evaluate wear in composite resin materials. The aim of this study was to verify how polishing and the type of abrasive can influence the wear rate of composite resin. The test was carried out on two groups. In one group we employed an ormocer and a hybrid composite that was polished group the composite was polished with the same abrasive paper plus a 1 microm and 0.25 microm grit diamond paste. A three-body wear test was performed using the metal sphere of the wear test machine, the composite and an abrasive. A diamond paste and aluminum oxide dispersion were used as abrasive. Analysis of the results showed that there was no difference between polishing techniques, but revealed a difference between abrasives.

  15. The measurement of the velocity of abrasive particles at the suction part of the cutting head

    Foldyna, J. (Josef); M. Zeleňák; Klich, J. (Jiří); Hlaváček, P.; Sitek, L. (Libor)


    To be able to optimize the design of the abrasive cutting head using numerical simulation, it is necessary to gather as much information about processes occurring in the cutting head as possible. The development of the numerical model of processes occurring in the abrasive water jet cutting head during the process of creation and forming of abrasive water jet is currently in progress at the Institute of Geonics in Ostrava. The verification of the model requires, among others, to determine the...

  16. Technical Possibilities of Noise Reduction in Material Cutting by Abrasive Water-jet

    Radvanská, Agáta; Ergić, Todor; IVANDIĆ, Željko; Hloch, Sergej; Valiček, Jan; Mullerova, Jana


    The technical procedure of noise reduction in material cutting by abrasive water-jet is described in this paper. The paper is aimed at the implementation of technical possibilities of noise reduction in the cutting of material by abrasive water-jet technology. Both the theoretical and experimental investigations were performed to verify and specify the new findings in the reduction of acoustic sound pressure at abrasive water-jet machining of engineering materials. By means of identification,...

  17. The measurement of the velocity of abrasive particlesat the suction part of the cutting head

    Foldyna, J. (Josef); M. Zeleňák; Klich, J. (Jiří); Hlaváček, P.; Sitek, L. (Libor); Z. Říha


    To be able to optimize the design of the abrasive cutting head using numerical simulation, it is necessary to gather as much information about processes occurring in the cutting head as possible. The development of the numerical model of processes occurring in the abrasive water jet cutting head during the process of creation and forming of abrasive water jet is currently in progress at the Institute of Geonics in Ostrava. The verification of the model requires, among others, to determine the...



    Abrasive jet cutting, as a more efficient machining or cutting method, has emerged in recent years in mining and machining industries, but the knowledge about velocity profile of abrasive jet flow lacks in general. In practice, the Polyacrylamide (PAM) is generally applied to jet fluid to increase the suspension of the abrasive particles. Also, the effects of PAM on jet flow are not very clear. In this paper, velocity fields of both the abrasive particles and the fluid were systematically studied with the PIV technology. The slip velocity between the abrasive particle and the surrounding fluid was subtracted out to give a further description of abrasive suspension jet. The effects of polymer PAM on both the fluid flow and the movement of the suspending abrasive particles were also measured. And it is found that the PAM is a proper type of additive to improve velocity fields for both the abrasive particles and the fluid in a jet. The results of the PIV measurement can help give a better understanding about the basic physics of abrasive suspension jet flow, and a good guidance to validate and develop reliable computational models to describe the jet.

  19. A comparison of the abrasiveness of six ceramic surfaces and gold.

    Jacobi, R; Shillingburg, H T; Duncanson, M G


    A type III gold alloy and six different ceramic surfaces were secured in an abrasion machine opposing extracted teeth to determine their relative abrasiveness and resistance to wear. The rankings of restorative materials from least abrasive to most abrasive were: gold alloy, polished; cast ceramic, polished; porcelain, polished; cast ceramic, polished and shaded; porcelain, polished and glazed; cast ceramic, cerammed skin shaded; and cast ceramic, cerammed skin unshaded. The ranking of materials from most wear-resistant to least wear-resistant was: gold alloy, cast ceramic cerammed, cast ceramic cerammed and shaded, porcelain polished, porcelain glazed, cast ceramic polished and shaded, and cast ceramic polished.

  20. Development of the white cast iron with niobium alloy, heat treating, to wear of the abrasive resistance; Desenvolvimento de uma liga de ferro fundido branco alto cromo com niobio, tratada termicamente, para resistencia ao desgaste abrasivo

    Farah, Alessandro Fraga


    This work presents the heat treatment and abrasion tests results of a white cast iron with niobium alloy. The hardening heat treatment were made 950, 1000, 1050 e 110 deg C temperatures cooled by forced air. The tempering treatment were made at 450, 500 e 550 deg C temperatures. The heat treating alloy were compared, in the abrasive tests, with commercial alloys used as hardfacing by welding process in wear pieces. The abrasion tests was realized in pin on disk test. Additional tests were carried out for microstructural characterization to identify the different phases presents in the alloys. In a general way, the alloy studies showed the best wear rate for the heat treatments that results in higher hardness. It performance was superior than that of the commercial alloys. (author)

  1. The Comparative Effect of Sugarcane Juice on the Abrasion-Corrosion Behavior of Fe-Cr-B Electric Arc Sprayed and Fe-Cr-C Weld Coatings

    Buchanan, Vernon E.


    Abrasion-corrosion tests were conducted on two commonly Fe-Cr-C shielded metal arc welding (SMAW) hardfacings used in the sugar industry and an arc sprayed Fe-Cr-based coating. The tests were performed on a modified block-on-ring tester with the coatings sliding against compressed sugarcane fiber in the presence of abrasive slurry. The findings showed that, in the presence of sugarcane juice and sand slurry, the SMAW coatings had similar wear performance while the abrasive wear of the arc-sprayed coating was superior to the SMAW coatings. In the presence of a neutral solution, the material loss from the arc-sprayed coating was similar to that obtained in the sugarcane juice while the SMAW coatings showed a marked decrease; this demonstrated that the arc-sprayed coating was more desirable in an abrasive-corrosion environment. The study also showed that the resistance to material does not follow the expected trend, in which wear resistance increases with increasing hardness.

  2. Diffuse corneal abrasion after ocular exposure to laundry detergent pod.

    Whitney, Rachel E; Baum, Carl R; Aronson, Paul L


    Although ocular injury from alkaline household cleaning products is well described, there is less known about the significance and extent of injury with ocular exposure to detergent pods. We report a 12-month-old with diffuse corneal abrasion caused by ocular contact with a laundry detergent pod. In addition to the known risks with aspiration with detergent pods, the potential for severe ocular injury is important for parents and clinicians to recognize. Children with ocular exposure to detergent pods should seek immediate medical care.

  3. Characteristics and mechanism of abrasive wear for thermoplastic polymers

    Xian Jia; Xiaomei Ling


    Abrasive wear characteristics of polyethylene, polystyrene, polymethylmethacrylate, nylon 1010 and polyvinyl chloride were investigated. The volume relative wear resistance coefficients of these thermoplastic polymers are 18%-35 % (hardened and low temperature tempered steel 45 was used as a comparing material), and have a linear correlation with square roots of their cohesive energy densities. The coefficients of linear correlation is 0.949. Wear morphologies were observed by scanning electron microscope (SEM). Main wear mechanism of the thermoplastic polymers includes brittle breaking for the hard and brittle polymers & plowing and fatiguing for the soft and tough ones.

  4. Mechanical issues in laser and abrasive water jet cutting

    Singh, Jogender; Jain, Sulekh C.


    In forging and other metal-working industries, lasers and abrasive water jets are being applied to cut a variety of metal products to improve productivity and reduce costs. As described in the following, both the processes have their unique cutting capabilities and characteristics. Before selecting one, however, users must be aware of how each technique influences the end product as well as its performance (e.g., high-cycle fatigue life). For this article, we examined the mechanics of these two cutting processes by studying their effects on Ti-6Al-4Vand A286 steel.

  5. Simulation of abrasive water jet cutting process: Part 2. Cellular automata approach

    Orbanic, Henri; Junkar, Mihael


    A new two-dimensional cellular automata (CA) model for the simulation of the abrasive water jet (AWJ) cutting process is presented. The CA calculates the shape of the cutting front, which can be used as an estimation of the surface quality. The cutting front is formed based on material removal rules and AWJ propagation rules. The material removal rule calculates when a particular part of the material will be removed with regard to the energy of AWJ. The AWJ propagation rule calculates the distribution of AWJ energy through CA by using a weighted average. The modelling with CA also provides a visual narrative of the moving of the cutting front, which is hard to observe in real process. The algorithm is fast and has been successfully tested in comparison to cutting fronts obtained with cutting experiments of aluminium alloy.

  6. Study on mineral processing technology for abrasive minerals

    Hong, Seong Woong; Yang, Jung Il; Hwang, Seon Kook; Choi, Yeon Ho; Cho, Ken Joon; Shin, Hee Young [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of)


    Buyeo Materials in Buyeogun, Choongnam province is a company producing feldspar concentrate, but does not yet utilize the garnet as abrasive material and other useful heavy minerals wasted out from the process of feldspar ore. The purpose of this study is to develop technology and process for the recovery of garnet concentrate. As results, the garnet is defined as ferro manganese garnet. The optimum process for recovery of garnet concentrate is to primarily concentrate heavy minerals from tailings of feldspar processing. And secondly the heavy minerals concentrated is dried and separated garnet concentrate from other heavy minerals. At this time, the garnet concentrate is yield by 0.176%wt from 0.31%wt of heavy minerals in head ore. The garnet concentrate contains 33.35% SiO{sub 2}, 12.20% Al{sub 2}O{sub 3}, 28.47% Fe{sub 2}O{sub 3}, 11.96% MnO. As for utilization of abrasive materials, a fundamental data was established on technology of grinding and classification. (author). 13 refs., 47 figs., 24 tabs.

  7. Abrasive waterjet machining of fiber reinforced composites: A review

    Kalla, D. K.; Dhanasekaran, P. S.; Zhang, B.; Asmatulu, R.


    Machining of fiber reinforced polymer (FRP) composites is a major secondary manufacturing activity in the aircraft and automotive industries. Traditional machining of these composites is difficult due to the high abrasiveness nature of their reinforcing constituents. Almost all the traditional machining processes involve in the dissipation of heat into the workpiece which can be resulted in damage to workpiece and rapid wear of the cutting tool. This serious issue has been overcome by water jetting technologies. Abrasive waterjet machining (AWJM) is a nontraditional method and one of the best options for machining FRPs. This paper presents a review of the ongoing research and development in AWJM of FRPs, with a critical review of the physics of the machining process, surface characterization, modeling and the newer application to the basic research. Variable cutting parameters, limitations and safety aspects of AWJM and the noise related issues due to high flow rate of water jet will be addressed. Further challenges and scope of the future development in AWJM are also presented in detail.

  8. Abrasive-assisted Nickel Electroforming Process with Moving Cathode

    REN, Jianhua; ZHU, Zengwei; XIA, Chunqiu; QU, Ningsong; ZHU, Di


    In traditional electroforming process for revolving parts with complex profiles, the drawbacks on surface of deposits, such as pinholes and nodules, will lead to varying physical and mechanical properties on different parts of electroformed components. To solve the problem, compositely moving cathode is employed in abrasive-assisted electroforming of revolving parts with complicated profiles. The cathode translates and rotates simultaneously to achieve uniform friction effect on deposits without drawbacks. The influences of current density and translation speed on the microstructure and properties of the electroformed nickel layers are investigated. It is found that abrasive-assisted electroforming with compound cathode motion can effectively remove the pinholes and nodules, positively affect the crystal nucleation, and refine the grains of layer. The increase of current density will lead to coarse microstructure and lower micro hardness, from 325 HV down to 189 HV. While, faster translational linear speed produces better surface quality and higher micro hardness, from 236 HV up to 283 HV. The weld-ability of the electroformed layers are also studied through the metallurgical analysis of welded joints between nickel layer and 304 stainless steel. The electrodeposited nickel layer shows fine performance in welding. The novel compound motion of cathode promotes the mechanical properties and refines the microstructure of deposited layer.

  9. Abrasive Wear Map of Polymer Tapes in Sand Dust Environment

    WU Tong-hai; DIAO Dong-feng


    To make clear the wear conditions of ATM (Automatic Teller Machine) tribosystem when servicing in Chinese sand dust environment, abrasive wear of two kinds of polymer tapes specified for ATM, PI (Polyimide) and PEN (Polyethylene-2, 6-naphthalenedicarboxylate), was investigated in simulated sand dust environment with ATM tape-scraper tribosystem under various conditions of loads and sliding distances. The surface profiles of worn tape were measured with a surface profiler in order to calculating the wear cross-section areas and the wear volumes. The specific wear rates of polymer tapes were calculated under load conditions of 0.6, 1 and 1.5 N, and wear mechanisms were investigated with optical topography photos. As main results, the specific wear rates show stage variations in the wear process and the wear resistance of polymer tape shows good relationship with the mechanical deformation factors. In consideration of the service life, four wear models are generalized according to the magnitude of specific wear rates,which include no wear, mild wear, normal wear and severe wear model and the corresponding wear mechanisms for the four wear models are discussed with typical worn topographies. Based on the wear models and corresponding wear mechanisms, the abrasive wear maps of two polymer tapes servicing in sand dust environments are concluded for its industrial applications.

  10. Polyurethanes from the crystalline prepolymers resistant to abrasive wear

    Domańska Agata


    Full Text Available The research aimed at the selection of polyurethanes synthesized from poly(tetramethylene ether glycol (PTMEG, as well as from two different isocyanates 4,4′-methylenebis(cyclohexylisocyanate (HMDI and 4.4′-methylenebis(phenyl isocyanate (MDI in order to obtain polyurethane with increased resistance to abrasive wear and degradation for bio-medical application. Polyurethanes were fabricated from crystalline prepolymers extended by water. The paper presents preliminary results on polyurethane surface wettability, friction coefficient for different couples of the co-working materials such as polyurethane-polyurethane, polyurethane-titanium alloy, polyurethane-alumina, in comparison to commonly used polyethylene-titanium alloy. Shear strength of polyurethane-alumina joint, as well as viscosity of prepolymers were also measured. The values of friction coefficient were compared to literature data on commercially available polyurethane with the trade name Pellethane. Polyurethanes obtained are characterized by low abrasive wear and low friction coefficient in couple with the titanium alloy, what makes them attractive as possible components of ceramic-polymer endoprosthesis joints.

  11. Influence of Hardness, Matrix and Carbides in Combination with Nitridation on Abrasive Wear Resistance of X210Cr12 Tool Steel

    Martin Orečný


    Full Text Available Materials used in abrasive wear conditions are usually selected according to their microstructure and hardness, however, other factors such as grain size, matrix saturation, carbides size and morphology are rarely considered. Therefore, the present study deals with the influence of different heat and chemical-heat treatments including their combination on abrasive wear resistance of X210Cr12 tool steel. The effects of material hardness, carbide morphology and microstructure on wear resistance after quenching and nitriding were also investigated. One sample series was quenched after austenitization at 960 °C for 20 min and tempered at 180 °C for 2 h. The second sample series was quenched from 1060 °C austenitization for 20 min and afterwards twice tempered at 530 °C for 1 h. From both the quenched and tempered states, one half of the samples was gas nitrided in NH3 atmosphere for 3 h and then diffusion annealed in N2 atmosphere for 4 h. Abrasion wear tests were performed by sliding the samples on Al2O3 paper. The samples weight loss was considered the main criterion for the wear resistance evaluation. The microstructures, nitrided layers and worn surfaces were observed using SEM microscopy. The highest abrasion wear resistance was obtained for the nitrided samples that were previously quenched from 1060 °C and tempered at 530 °C.

  12. Effect of microstructure on abrasion amount of steel balls for mill%显微组织对球磨机钢球磨损量的影响

    张达富; 刘锦燕; 陈义


    Effect of microstructure on abrasion of steel balls by two different heat-treatment was studied by the abrasion-test machine,metalloscope and scanning electron microscopy (SEM) .The results show that the abrasion amount of high hardness steel balls with martensite microstructure is larger,and the relatively low hardness of tempered martensite and retained austenite erosion rate is lower.It is found that the abrasion mechanism of steel balls is given priority with peeling method,which indicates that the wear resistance of steel balls is directly related to the microstructure.%分别采用磨损试验机、金相显微镜和扫描电镜(SEM)等研究了两种热处理工艺下的钢球显微组织对磨损量的影响.结果表明,硬度较大的含马氏体组织的钢球磨损量较大,而硬度相对较低的回火马氏体+残留奥氏体磨损量较低.钢球的磨损机理以剥落方式为主,这说明钢球的耐磨性与显微组织有直接关系.

  13. Improvement of abrasion resistance in artificial seawater and corrosion resistance in NaCl solution of 7075 aluminum alloy processed by laser shock peening

    Wang, Hao; Ning, Chengyi; Huang, Yihui; Cao, Zhenya; Chen, Xiaoxiao; Zhang, Wenwu


    As 7075 aluminum alloy is widely used in a humid environment, in order to enhance its abrasion resistance and electrochemical corrosion resistance, the paper studied the effect of laser shock peening on abrasion resistance in artificial seawater and corrosion resistance in 3.5% NaCl solution of 7075 aluminum alloy. Result shows that when specimens were treated once and twice with 7.17 GW/cm2 the abrasion loss would be reduced by 43.75% and 46.09% compare to untreated respectively, and the corrosion rate of 7075 aluminum alloy could be reduced as much as 50.32% by LSP treatment with 7.17 GW/cm2. What's more, the effects on the microhardness, microstructure and residual stress with different LSP impacts and power density were investigated to find out strengthening mechanism of laser shock peening, which were observed and measured by microhardness tester, optical microscope and X-ray diffraction (XRD) residual stress tester. In the entire laboratory tests, it is considered that LSP is a practical option to improve abrasion resistance in seawater and corrosion resistance of 7075 aluminum alloy.

  14. Estudo in vitro da abrasividade de dentifrícios In vitro study of dentifrice abrasivity

    Antonio Carlos Canabarro ANDRADE JUNIOR


    Full Text Available O objetivo do presente estudo é avaliar a abrasividade de 15 dentifrícios, utilizando o aparelho Einlehner AT 1000. Uma solução contendo 50 g de cada creme dental mais 800 ml de água destilada era colocada no referido aparelho, que promovia 174.000 rotações da haste metálica, com um cilindro descartável de borracha, sobre uma tela de cobre pesada previamente (P1, por 100 minutos. Com o término da operação, a tela era lavada, seca e novamente pesada (P2. Através da equação: (P1-P2 ÷ 3,07 x 10-4 encontrava-se o número de gramas/metro2. Cada dentifrício foi testado 3 vezes e o valor final apresentado é a média dos 3 testes. Adicionalmente foram investigados o pH e o teor de sólidos das diferentes marcas. Os resultados mostraram que os dentifrícios possuem uma grande variação no grau de abrasão. As 3 marcas mais abrasivas foram: Close Up com flúor, Colgate Antitártaro e Oral B Dentes e Gengivas, as duas primeiras com dióxido de silício. As 3 marcas menos abrasivas foram: Colgate M.F.P. com cálcio, Gessy com flúor e Signal com flúor, todas com carbonato de cálcio. Os dentifrícios Close Up com flúor, Kolynos Ação Total e Oral B Dentes e Gengivas apresentaram um pH abaixo de 7, que pode indicar um possível efeito erosivo, associado à abrasão. Novas pesquisas são necessárias para comparar esses resultados com cremes dentais internacionais.The aim of the present study was to determine the abrasivity of 15 dentifrices, using Einlehner AT 1000 equipment. A solution containing 50 g of dentifrice and 800 ml of distilled water was placed in the equipment, at 174.000 revolutions of the metal stem, with a disposable rubber cylinder on a previously weighed copper screen (P1, for 100 min. After the procedure was over, the screen was washed, dried, and weighed again (P2. The number of g/m2 was found by using the equation: (P1-P2 ÷ 3,07 x 10-4. Each dentifrice was tested three times, and the final value was the average of

  15. Cutting Tools, Files and Abrasives. Pre-Apprenticeship Phase 1 Training.

    Lane Community Coll., Eugene, OR.

    This self-paced student training module on cutting tools, files, and abrasives is one of a number of modules developed for Pre-apprenticeship Phase 1 Training. Purpose of the module is to enable students to identify and explain the proper use and care of various knives, saws, snips, chisels, and abrasives. The module may contain some or all of the…

  16. Potential Use of Abrasive Air-Propelled Agricultural Residues for Weed Control

    A new postemergence weed control tactic is proposed for organic production systems that results in plant abrasion and death upon assault from abrasive grits propelled by compressed air. Grit derived from granulated walnut shells was delivered by a sand blaster at 517 kPa at distances of 30 to 60 cm ...

  17. A review of engineering control technology for exposures generated during abrasive blasting operations.

    Flynn, Michael R; Susi, Pam


    This literature review presents information on measures for controlling worker exposure to toxic airborne contaminants generated during abrasive blasting operations occurring primarily in the construction industry. The exposures of concern include respirable crystalline silica, lead, chromates, and other toxic metals. Unfortunately, silica sand continues to be widely used in the United States as an abrasive blasting medium, resulting in high exposures to operators and surrounding personnel. Recently, several alternative abrasives have emerged as potential substitutes for sand, but they seem to be underused Some of these abrasives may pose additional metal exposure hazards. In addition, several new and improved technologies offer promise for reducing or eliminating exposures; these include wet abrasive blasting, high-pressure water jetting, vacuum blasting, and automated/robotic systems. More research, particularly field studies, is needed to evaluate control interventions in this important and hazardous operation.

  18. Comparison of shear bond strength and surface structure between conventional acid etching and air-abrasion of human enamel.

    Olsen, M E; Bishara, S E; Damon, P; Jakobsen, J R


    Recently, air-abrasion technology has been examined for potential applications within dentistry, including the field of orthodontics. The purpose of this study was to compare the traditional acid-etch technique with an air-abrasion surface preparation technique, with two different sizes of abrading particles. The following parameters were evaluated: (a) shear bond strength, (b) bond failure location, and (c) enamel surface preparation, as viewed through a scanning electron microscope. Sixty extracted human third molars were pumiced and divided into three groups of 20. The first group was etched with a 37% phosphoric acid gel for 30 seconds, rinsed for 30 seconds, and dried for 20 seconds. The second and third groups were air-abraded with (a) a 50 microm particle and (b) a 90 microm particle of aluminum oxide, with the Micro-etcher microabrasion machine (Danville Engineering Inc.). All three groups had molar stainless steel orthodontic brackets bonded to the buccal surface of each tooth with Transbond XT bonding system (3M Unitek). A Zwick Universal Testing Machine (Calitek Corp.) was used to determine shear bond strengths. The analysis of variance was used to compare the three groups. The Adhesive Remnant Index (ARI) was used to evaluate the residual adhesive on the enamel after bracket removal. The chi square test was used to evaluate differences in the ARI scores among the groups. The significance for all tests was predetermined at p shear bond strength among the three groups (p = 0.0001). The Duncan Multiple Range test showed a significant decrease in shear bond strength in the air-abraded groups. The chi square test revealed significant differences among the ARI scores of the acid-etched group and the air-abraded groups (chi(2) = 0.0001), indicating no adhesive remained on the enamel surface after debonding when air-abrasion was used. In conclusion, the current findings indicate that enamel surface preparation using air-abrasion results in a significant lower

  19. Investigation of the abrasive lapping of oxide ceramics

    Almaz Mullayanovich Khanov


    Full Text Available In this paper the methods of ceramic materials treatments are summarized. For the treatment of a technical ceramics the grinding and finishing processes including the description of the treatment steps are reported. In the first step, up to 80% of the material is polished away and the grinding is carried out at increased velocities using a tool with larger grains. In the second step of grinding, the amount of the removed material is decreased and this step is carried out using the abrasive tool with smaller grains. The third step referred as finishing is done by diamond abrasive micro-powders and a paste with a certain grain size. Often, after this step the polishing is performed in order to achieve the precision class of 1-3 and low surface roughness. The abrasive finishing of the materials based on the oxide ceramics VSH-75 is investigated. It is found that the performance ability of the diamond micro-powder is higher by a factor of 15-30 compared to the electrocorundum and green silicon carbide micro-powders. By increasing the graininess, the amount of removed material and the roughness of a treated surface are increased. In order to achieve the Rz=0.8 µm it is recommended to use a synthetic diamond micro-powder ASM20. Additionally, the influence of the contact pressure of the part onto the lap in the range from 25 to 150 kPa is investigated. With the increase of the contact pressure from 25 to 50 kPa, the total removal is significantly increasing whereas the relative diamond micro-powder consumption and surface roughness are essentially decreasing. Further increase of the contact pressure up to 150 kPa has smaller effect on the process parameters, while the cracks appear at the tool surface deteriorating the external view of the tool. The optimal contact pressure during finishing of the ceramic using the cast iron lap SCH-28 is about 50-100 kPa

  20. Improved Corrosion and Abrasion Resistance of Organic-Inorganic Composite Coated Electro-galvanized Steels for Digital TV Panels

    Jo, Du-Hwan; Noh, Sang-Geol; Park, Jong-Tae; Kang, Choon-Ho [POSCO Technical Research Laboratories, Pohang (Korea, Republic of)


    Recently, household electronic industries require environmentally-friendly and highly functional steels in order to enhance the quality of human life. Customers especially require both excellent corrosion and abrasion resistant anti-fingerprint steels for digital TV panels. Thus POSCO has developed new functional electro-galvanized steels, which have double coated layers with organic-inorganic composites on the zinc surface of the steel for usage as the bottom chassis panel of TVs. The inorganic solution for the bottom layer consists of inorganic phosphate, magnesium, and zirconium compounds with a small amount of epoxy binder, and affords both improved adhesion properties by chemical conversion reactions and corrosion resistance due to a self-healing effect. The composite solution for the top layer was prepared by fine dispersion of organic-inorganic ingredients that consist of a urethane modified polyacrylate polymer, hardener, silica sol and a titanium complex inhibitor in aqueous media. Both composite solutions were coated on the steel surface by using a roll coater and then cured through an induction furnace in the electro-galvanizing line. New anti-fingerprint steel was evaluated for quality performance through such procedures as the salt spray test for corrosion resistance, tribological test for abrasion resistance, and conductivity test for surface electric conductance regarding to both types of polymer resin and coating weight of composite solution. New composite coated anti-fingerprint steels afford both better corrosion resistance and abrasion properties compared to conventional anti-fingerprint steel that mainly consists of acrylate polymers. Detailed discussions of both composite solutions and experimental results suggest that urethane modifications of acrylate polymers of composite solutions play a key role in enhanced quality performances.

  1. Surface quality of marble machined by abrasive water jet

    Ramy Abdullah


    Full Text Available This paper presents a study conducted to examine the effect of cutting parameters, namely standoff distance, nozzle traverse speed (TS, abrasive flow rate (AFR, and material type on cutting performance for two types of marble workpieces, Carrara white and Indian green. Statistical analysis was undertaken to assess the influence of the cutting parameters on the process performances in terms of surface roughness, surface waviness, and Kerf taper ratio. The results showed that the TS and material type were the most significant factors that affected surface roughness and Kerf taper ratio. Also, although AFR was found to have significant effect on surface waviness, it had no noticeable influence on surface roughness nor Kerf taper ratio.

  2. Graphite Intended for Green Engineering Developed by Noncontaminant Reverse Abrasion

    Roberto Baca Arroyo


    Full Text Available Graphite intended for green engineering was synthesized by noncontaminant reverse abrasion, which consists of graphite layers assembled with thickness controlled on SiC sandpaper as insulating substrate. Phase formation of the graphite layers was validated by X-ray diffraction studies and its finished profile by Atomic Force Microscopy (AFM. Transport parameters of only three layers were evaluated from current-voltage curves. Mathematical functions such as derivative and modulation of a signal have been built by graphite circuits using different performance principles, compared to those used with silicon devices. The trends related to electronic engineering should be achieved with design of the graphite-based devices to facilitate their mass production in the near future.

  3. Effect of Heat Treatment on the Abrasive Wear Behavior of High Chromium Iron under Dry Sliding Condition

    A.A. Ayeni


    Full Text Available The effect of heat treatment on the abrasive wear behavior of high chromium cast iron (NF253AHT under dry sliding condition has been investigated. Rectangular cross sectioned samples of the alloy were produced by sand casting. After casting, the samples were machined to equal dimensions of 50 mm x 15 mm x 10 mm and heat treated by annealing, hardening and tempering. Abrasive wear tests were carried out on the samples using the pin-on-disc wear test. The tests were carried out under restricted values of speed, load and time. Within this limit, the hardened sample displayed a superior wear resistance, while the annealed sample displayed the weakest wear resistance. A graphical model (wear map displaying all the wear regimes of the alloy, which may serve as a wear predictive tool was subsequently developed from the results of the wear tests. With the exception of the as-cast and annealed specimen, all other specimens (hardened and tempered have functioned adequately in wear prone environment, but with different degree of effectiveness. Hence, the hardened and tempered samples can be used in shot blast equipments and in the grinding of minerals.


    李晓红; 王建生; 杨林; 卢义玉; 孙家骏


    为了提高坚硬岩石巷道的掘进速度和质量,研究了准直管磨料射流用于岩石巷道掘进的方案,分析了准直管磨料射流装备的结构特点和工作原理。试验研究了准直管结构参数、磨料参数、进给速度对射流切割效果的影响。初步研究表明这一设想基本可行,是一种值得探讨的新型掘进方法。%A new-type tunneling system, Collimated Abrasive Water Jet(CAWJ)cutter, is develped to increase the tunneling speed and improve the cutting quality in hard rock. And its characteristics of configuration and operating principle are discussed. The effects of cutting hard rock with various operating parameters on the cutting efficiency of CAWJ are analyzed. Research results show that it is primarily feasible for tunneling hard rock with CAWJ.

  5. Development of Abrasive Selection Model/Chart for Palm Frond Broom Peeling Machine Design



    Full Text Available A model for predicting the friction required by a palm frond broom peeling machine for effective peeling of palm leaf to broom bristle and a chart for selecting the best abrasive material for this machine’s peeling operation were developed in this study using mechanistic modeling method. The model quantified the relationship between the coefficient of friction and other operational parameters of this machine while the abrasives selection chart constitutes a plot of this measured friction parameter against the abrasive materials used in palm frond broom peeling machine fabrication. The values of the coefficient of friction of palm leaf on different abrasive materials used in this plot were determined from experimental study of the effect of moisture content level of naturally withered palm leaves (uninfluenced by external forces on their coefficient of friction with the abrasives. Results revealed the average moisture content of palm leaf this machine can peel effectively as 6.96% and also that the roughest among the abrasives that approximate the coefficient of friction for a specific design of this peeling machine gives maximum peeling efficiency. Thus, the roughest among the abrasive materials that approximate the coefficient of friction for a specific design of this machine should be selected and used for its fabrication and operation.

  6. Influence of Impact Energy on Impact Corrosion-abrasion of High Manganese Steel


    The impact corrosion-abrasion properties and mechanism of high manganese steel were investigated under different impact energies. The result shows that the wearability of the steel decreases with the increase of the impact energy. The dominant failure mechanism at a lower impact energy is the rupture of extrusion edge along root and a slight shallow-layer spalling. It transforms to shallow-layer fatigue flaking along with serious corrosion-abrasion when the impact energy is increased, and finally changes to bulk flaking of hardened layer caused by deep work-hardening and heavy corrosion-abrasion.

  7. Effects of mechanical cleaning by manual brushing and abrasive blasting on lime render coatings on Architectural Heritage

    Iglesias-Campos, M. A.


    Full Text Available This research studies the effects of mechanical cleaning by brushing and by abrasive blasting on the lime render coating of a façade. After analysing the properties of the material, the deposits to be removed and their possible influence on the treatment, different cleaning tests were made by manual brushing and by blasting with three varieties of abrasives at 45° and 75° angles, keeping the other parameters constant. Taking the restorer’s perspective as a starting point, and in order to fulfil the practical requirements of an intervention, tests were evaluated with macro-photography, USB digital microscope and stereomicroscope with 3D visualization and measurement. From the results can be concluded that abrasives with low friability and greater grain size than the space between mortar aggregates blasted at a 75° angle reduce the differential erosion compared to other abrasives; although manual brushing has less impact on the surface.En este trabajo se estudian los efectos de las limpiezas mecánicas con cepillado y con proyección de abrasivos sobre un revestimiento exterior de cal. Tras documentar las propiedades del material, de los depósitos superficiales y de su posible influencia en el tratamiento, se realizaron diferentes catas de limpieza con cepillado manual y con proyección de tres abrasivos con ángulos de 45° y 75° manteniendo constantes el resto de parámetros. Partiendo de la visión del conservador-restaurador y de un carácter práctico según las necesidades reales de intervención, los ensayos se evaluaron con macrofotografía, microscopio digital USB y microscopio estereoscópico con visualización y medición en 3D. De los resultados se determina que los abrasivos de baja friabilidad y granulometría mayor que el espacio entre los áridos del mortero proyectados con un ángulo de 75° reducen la erosión diferencial en comparación a otros abrasivos, aunque el cepillado manual altera menos la superficie.

  8. An Experimental investigation of sea sand as an Abrasive material in vibrating chamber by using Tungsten Carbide Nozzle in Abrasive Jet machining Process.

    N. S. Pawar


    Full Text Available A large number of investigation carried out in Abrasive jet machining and water jet machining process with different parameter but no detailed work have been found or carried out by using sea sand as an abrasive in AJM process by using different types of nozzles and variable parameters. The present work gives performance of sand having grain structure of 100-150 micron in the tungsten carbide nozzle. Theexperimentation in this study give characteristic of sea sand as abrasive material. The parameter like pressure, standoff distance of nozzle from work piece keeping constant and variable. It give the result of material removal rate , powder flow rate, similar to actually abrasive used like Aluminum oxide, silicon oxide etc. The R square value o.97 to 0.996 degree of polynomial equation. It is also notice that width of cut slightly increase with increase of feed rate .The taper cut slot was found to be a higher at greater stand of distance and work feed rate .Tungsten carbide is very hard. It maintain high cutting ability as abrasive strike on work piece

  9. Study on planarization machining of sapphire wafer with soft-hard mixed abrasive through mechanical chemical polishing

    Xu, Yongchao; Lu, Jing; Xu, Xipeng


    This study investigated the material removal mechanism of sapphire wafer with soft-hard mixed abrasives through mechanical chemical polishing (MCP). The polishing film, which contains diamond as hard abrasives and high reactivity silica as soft abrasives, is prepared through sol-gel technology. Silica abrasives with regular spherical shape and high reactivity are prepared through hydrolysis-precipitation. Diamond grits with three different particle sizes are used as abrasives. Results show that the rate of material removal of mixed abrasives during MCP is more than 52.6% of that of single hard abrasives and the decrease in surface roughness is more than 21.6% of that of single hard abrasives. These results demonstrate that the ideal planarization of sapphire wafer with high removal rate and good surface quality can be achieved when the effect of mechanical removal of hard abrasives and the chemical corrosion effect of soft abrasives are in dynamic equilibrium. A model that describes the material removal mechanism of sapphire with mixed abrasives during MCP is proposed. The results of thermodynamic calculation and polishing residue analysis are used to demonstrate the rationality of the model.

  10. Ice Abrasion on Fiber Reinforced Concrete : A Study on the Effects of Various Types of Fiber and the Reliability of the Laboratory Measurements

    Sætre, Kristian


    The purpose of this study has been to compare how fiber reinforced concretes, using different amounts and types of fiber, behave compared to standard offshore concretes without fiber in regard to ice abrasion. The effect of fiber addition on the freeze-thaw resistance has also been studied. Due to various observations during testing, a large part of this study has gradually come to deal with the accuracy and the reliability of the measurement equipment and methods used during these ice abrasi...

  11. Surface assessment and modification of concrete using abrasive blasting

    Millman, Lauren R.

    Composite systems are applied to concrete substrates to strengthen and extend the service life. Successful restoration or rehabilitation requires surface preparation prior to the application of the overlay. Surface coatings, waterproofing systems, and other external surface applications also require surface preparation prior to application. Abrasive blast media is often used to clean and uniformly roughen the substrate. The appropriate surface roughness is necessary to facilitate a strong bond between the existing substrate and overlay. Thus, surface modification using abrasive blast media (sand and dry ice), their respective environmental effects, surface roughness characterization prior to and after blasting, and the adhesion between the substrate and overlay are the focus of this dissertation. This dissertation is comprised of an introduction, a literature review, and four chapters, the first of which addresses the environmental effects due to abrasive blasting using sand, water, and dry ice. The assessment considered four response variables: carbon dioxide (CO2) emissions, fuel and energy consumption, and project duration. The results indicated that for sand blasting and water jetting, the primary factor contributing to environmental detriment was CO22 emissions from vehicular traffic near the construction site. The second chapter is an analysis of the International Concrete Repair Institute's (ICRI) concrete surface profiles (CSPs) using 3-D optical profilometry. The primary objective was to evaluate the suitability of approximating the 3-D surface (areal) parameters with those extracted from 2-D (linear) profiles. Four profile directions were considered: two diagonals, and lines parallel and transverse to the longitudinal direction of the mold. For any CSP mold, the estimation of the 3-D surface roughness using a 2-D linear profile resulted in underestimation and overestimation errors exceeding 50%, demonstrating the inadequacy of 2-D linear profiles to

  12. Treatment of gingival hyperpigmentation with rotary abrasive, scalpel, and laser techniques: A case series.

    Murthy, M Bhanu; Kaur, Jasjit; Das, Rupali


    Melanin pigmentation often occurs in the gingiva as a result of an abnormal deposition of melanin, due to which the gums may appear black, but the principles, techniques, and management of the problems associated with gingival melanin pigmentation are still not fully established. Depigmentation procedures such as scalpel surgery, gingivectomy with free gingival autografting, electrosurgery, cryosurgery, chemical agents such as 90% phenol and 95% alcohol, abrasion with diamond bur, Nd: YAG laser, semiconductor diode laser, and CO2 laser have been employed for removal of melanin hyper pigmentation. The following case series describes three different surgical depigmentation techniques: scalpel surgery, abrasion with rotary abrasive, and a diode laser. Better results of depigmentation were achieved with diode laser than conventional scalpel and with rotary abrasion with respect to esthetics. The results point out that lasers are an effective and a safe means to removal of hyperpigmentation from the gingiva. Healing was uneventful and no repigmentation occurred.

  13. Abrasion resistance of biaxially oriented polypropylene films coated with nanocomposite hard coatings

    Wang, Jing; Zhu, Yaofeng; Fu, Yaqin


    KMnO4-treated, functionalized, biaxially oriented polypropylene (BOPP) films coated with nano-silica hybrid material were synthesized. The abrasion resistance of the films was examined using a reciprocating fabric abrasion tester. Functional groups were confirmed by Fourier-transform infrared spectroscopy. Contact angle measurements were performed on the BOPP film surface to quantify the effectiveness of the functionalization. Results indicate that the abrasion resistance and roughness of the composite film were significantly affected by the modification of the BOPP film. Water surface contact angle of the modified BOPP films decreased from 90.1° to 71.4°,when KMnO4 concentration increased from 0 M to 0.25 M. Wettability of the BOPP films clearly improved after KMnO4 treatment. Abrasion resistance of the functionalized films coated with hybrid materials improved by 27.4% compared with that of the original film.


    Zh. A. Mrochek


    Full Text Available The paper presents investigation results pertaining to magneto-abrasive machining of product surfaces formed by electromagnet surfacing with a plastic deformation of P6M5K5 powder. 

  15. Clarification of abrasive jet precision finishing with wheel as restraint mechanisms and experimental verification


    According to the critical size ratio for the characteristic particle size to film thickness between grinding wheel and work, the machining mechanisms in abrasive jet precision finishing with grinding wheel as restraint can be categorized into four states, namely, two-body lapping, three-body polishing, abrasive jet machining and fluid hydrodynamic shear stress machining. The critical transition condition of two-body lapping to three-body polishing was analyzed. The single abrasive material removal models of two-body lapping, three-body polishing, abrasive jet finishing and fluid hydrodynamic shear stress machining were proposed. Experiments were performed in the refited plane grinding machine for theoretical modes verification. It was found that experimental results agreed with academic modes and the modes validity was verified.

  16. Study of kerf geometry of multilayers materials in abrasive water jet cutting process

    Barabas Bogdan


    Full Text Available The use of abrasive jet cutting in case of multilayers materials, shows particularities and difficulties, due to different hardness and thickness of layers. This paper studies changes, occurred in the kerf geometry at passing of abrasive particles, through layers with different hardness and aims to establish a link between hardness and thickness of the layers and kerf geometry because processing accuracy is determined by the geometry of the cut. Thus, is proposed a novel algorithm based on minimization of angle of kerf, for optimization a cutting process in abrasive water jet technology, which can be utilized for materials with different hardness in layers. Direct effect of optimization of cutting consist in increasing efficiency, dimensional precision, traverse velocity, and decreasing the amount of used abrasive garnet.

  17. The effect on cast post dimensions of casting investment and airborne particle abrasion.

    Hashem, Danya; German, Matthew J; Wassell, Robert W


    Cast posts can sometimes prove difficult to seat fully during fitting. This study compared two different liquid/water dilutions for phosphate bonded investment and the effect of controlled airborne particle abrasion on resulting post diameter. After measuring polymeric post patterns (n = 18), 3 groups were invested using concentrated solution and 3 groups using dilute solution. After casting they were weighed and remeasured then exposed to airborne particle abrasion. Both solutions produced oversized cast posts. Mean diameter reduction during airborne particle abrasion was 8 microm/10s taking an average of 41s to reach precast size. Where a post pattern fits tightly, airborne particle abrasion for 70s should reduce the casting sufficiently to accommodate the cement lute.


    Delia BAHRIM


    Full Text Available Dental abrasion appears as a complex phenomenon among the multitude of clinical manifestations occurring in patients who require a complex oral rehabilitation. The therapeutical solutions for such cases are quite elaborate, involving interdisciplinary contributions from the part of various specialists.Obviously, elucidation of the complex cases of dental abrasion is possible when their standardized classification and, equally, a well-established therapeutical conduct, considering the class of dental abrasion, are available.Considering the advance of the adhesive techniques, the conservative treatment of dental abrasion is more indicated than the conventional method.Consequently, a 3-stage protocol of coronary reconstruction is recommended in cases of erosion with undersizing of the lower segment. The immediate aesthetic results are satisfacatory for the patient, as well as the functional ones, not requiring longer accomodation times. The reconstructions are resistant, due to the progress recorded by the adhesive techniques and composite resins (nano-hybrids, nano-composites.

  19. Drawing Light-fields: Hand-drawn Approaches to Abrasion Holography

    Duke, T.


    Abrasion holography has received little attention since the technique was described by William J. Beaty in the early 1990's. In this paper the limitations of abrasion holography are explored, and new approaches are presented which expand the possibilities of the medium. New tools presented here offer new possibilities to the artist wishing to draw holograms by hand. Methods are described by which complex curves and organic forms can be constructed by hand more easily and intuitively than previously described. In an analysis of reconstruction lighting and viewing geometries, new solutions to reduce or eliminate distortions are suggested. Various tools, materials, and scratch geometries are considered for optimum 3D illusion. A new class of abrasion holograms is presented that use elliptical, hypotrochoidal, and epitrochoidal scratch geometries, exhibiting novel animation effects. In conclusion, a method for embossing abrasion holograms with the aid of an etching press is described.


    ZHU Pailong; ZHOU Jinjin; TANG Dianbo


    Based on the two existing abrasive water-jet(AWJ) systems, the dia-jet (or pre-jet) and the post-jet, a new type of abrasive water-jet system is put forward, which combines the dia-jet's advantage, low operating system pressure, slender stream jet, and more concentrative abrasive in the blended stream, with merits of post-jet, the less sophisticate apparatus, successive supply of abrasives.The theoretic analysis is brought out in detail, and the nozzle system structure is concisely illustrated.Its relevant experiment results are demonstrated, proving that this new system is effective in various aspects, enlarging penetrating capability without raising system pressure, saving machining power supply, lessening energy loss, etc.

  1. Abrasion and deformed layer formation of manganese-zinc ferrite in sliding contact with lapping tapes

    Miyoshi, K.; Buckley, D. H.; Tanaka, K.


    Wear experiments were conducted using replication electron microscopy and reflection electron diffraction to study abrasion and the deformed layers produced in single-crystal Mn-Zn ferrite simulated heads during contact with lapping tapes. The crystaline state of the head is changed drastically during the abrasion process. Crystalline states ranging from nearly amorphous to highly textured polycrystalline can be produced on the wear surface of a single-crystal Mn-Zn ferrite head. The total thickness of the deformed layer was approximately 0.8 microns. This thickness increased as the load and abrasive grit size increased. The anisotropic wear of the ferrite was found to be inversely proportional to the hardness of the wear surface. The wear was lower in the order 211 111 10 0110. The wear of the ferrite increased markedly with an increase in sliding velocity and abrasive grit size.

  2. A Study of effect of Process Parameters of Abrasive jet machining

    Jagtar Singh


    Full Text Available As Abrasive jet machining (AJM is similar to sand blasting and effectively removes hard and brittle materials. AJM has been applied to rough working such as deburring and rough finishing. With the increase of needs for machining of ceramics, semiconductors, electronic devices and L.C.D., AJM has become a useful technique for micromachining. This paper deals with various experiments which were conducted to assess the influence of abrasive jet machining (AJM process parameters on material removal rate and diameter of holes of glass plates using aluminum oxide type of abrasive particles. The experimental results of the present work are used to discuss thevalidity of proposed model as well as the other models. With the increase in nozzle tip distance (NTD, the top surface diameter and bottom surface diameter of hole increases as it is in general observation of abrasive jet machining process. As the pressure increases, the material removal rate (MRR is also increased.

  3. Chemical Mechanical Polishing of Glass Substrate with α-Alumina-g-Polystyrene Sulfonic Acid Composite Abrasive

    LEI Hong; BU Naijing; ZHANG Zefang; CHEN Ruling


    Abrasive is the one of key influencing factors during chemical mechanical polishing(CMP) process. Currently, α-Alumina (α-Al2O3) particle, as a kind of abrasive, has been widely used in CMP slurries, but their high hardness and poor dispersion stability often lead to more surface defects. After being polished with composite particles, the surface defects of work pieces decrease obviously. So the composite particles as abrasives in slurry have been paid more attention. In order to reduce defect caused by pure α-Al2O3 abrasive, α-alumina-g-polystyrene sulfonic acid (α-Al2O3-g-PSS) composite abrasive was prepared by surface graft polymerization. The composition, structure and morphology of the product were characterized by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), time-of-flight secondary ion mass spectroscopy(TOF-SIMS), and scanning electron microscopy(SEM), respectively. The results show that polystyrene sulfonic acid grafts onto α-Al2O3, and has well dispersibility. Then, the chemical mechanical polishing performances of the composite abrasive on glass substrate were investigated with a SPEEDFAM-16B-4M CMP machine. Atomic force microscopy(AFM) images indicate that the average roughness of the polished glass substrate surface can be decreased from 0.835 nm for pure α-Al2O3 abrasive to 0.583 nm for prepared α-Al2O3-g-PSS core-shell abrasive. The research provides a new and effect way to improve the surface qualities during CMP.

  4. Multi-objective Optimization of Process Performances when Cutting Carbon Steel with Abrasive Water Jet

    M. Radovanović


    Full Text Available Multi-objective optimization of process performances (perpendicularity deviation, surface roughness and productivity when cutting carbon steel EN S235 with abrasive water jet is presented in this paper. Cutting factors (abrasive flow rate, traverse rate and standoff distance were determined when perpendicularity deviation and surface roughness are minimal and productivity is maximal. Multi-objective genetic algorithm (MOGA was used for the determination set of nondominated optimal points, known as Pareto front.

  5. Examination of Wetting by Liquid Zinc of Steel Sheets Following Various Kinds of Abrasive Blasting

    Cecotka M.


    Full Text Available Abrasive blasting is one of the methods of surface working before hot-dip zinc-coating. It allows not only to remove products of corrosion from the surface, but it also affects the quality of the zinc coating applied later, thereby affecting wettability of surface being zinc-coated. The surface working can be done with different types of abrasive material.

  6. Release of copper-amended particles from micronized copper-pressure-treated wood during mechanical abrasion

    Civardi, Chiara; Schlagenhauf, Lukas; Kaiser, Jean-Pierre; Hirsch, Cordula; Mucchino, Claudio; Wichser, Adrian; Wick, Peter; Schwarze, Francis W. M. R.


    Background We investigated the particles released due to abrasion of wood surfaces pressure-treated with micronized copper azole (MCA) wood preservative and we gathered preliminary data on its in vitro cytotoxicity for lung cells. The data were compared with particles released after abrasion of untreated, water (0% MCA)-pressure-treated, chromated copper (CC)-pressure-treated wood, and varnished wood. Size, morphology, and composition of the released particles were analyzed. Results Our resul...

  7. Neutralization of potential land mine hazards by abrasive waterjet use

    Summers, David A.; Fossey, Robert D.; Thompson, S. J.


    A method of neutralizing landmines in which the integrity of the surrounding terrain is retained is herein described. High pressure waterjets which can be used to detect the presence of landmines can then be used to remove the soil and other cover in a plane immediately adjacent to and around the mine so that the side of the mine can be visually inspected through a remote television camera. At that time the flow of water is channeled through a line in which small particles of sand are added to the waterjet which is at a pressure of between 3,000 and 10,000 psi depending on the device which is used. Jet flow rates are on the order of 5 gpm depending on the nozzle configuration used. By bringing this abrasive stream in along a lateral plane through the mine it is possible to intersect, and neutralize, the fusing systems most likely to be used to initiate the charge, in a single pass. At higher flow rates, as the cut is made the jet will generate significant turbulence in the mine body, sufficient to remove a considerable quantity of the explosive which is resident within the mine at the same time as the mine is being dissected. The precision of cut achievable is shown by the longitudinal cutting into two parts of live detonators, as well as representative mine bodies.

  8. Microstructure formation and properties of abrasion resistant cast steel

    S. Parzych


    Full Text Available The so-called adamitic cast steels are characterised by a high abrasion resistance. These cast steels are of a pearlitic matrix with uniformly distributed hypereutectoid cementite precipitates. Apart from hypereutectoid cementite very often transformed ledeburite also occurs in the microstructure of these cast steels. Such cast steels contain chromium (app. 1 % and nickel (app. 0.5 % as alloy additions and sometimes their silicon content is increased. The presence of molybdenum is also permissible (app. 0.4 %. The basic problem in application of these steels for structural elements constitutes their insufficient crack resistance. An improvement of mechanical properties by changes of morphology of hypereutectoid cementite and transformed ledeburite precipitates by means of the heat treatment application was the aim of this study. G200CrNiMo4-3-3 cast steel was the investigated material. Changes in the morphology of hypereutectoid cementite and transformed ledeburite obtained due to the heat treatment are described in detail in the present paper. An influence of the microstructure changes on impact toughness of the investigated cast steel is presented. Investigations performed within this study will serve for the microstructure optimisation on account of functional qualities of this cast steel.

  9. Laboratory Measurements of Particulate Matter Concentrations from Asphalt Pavement Abrasion

    Fullová, Daša; Đurčanská, Daniela


    The issue of emissions from road traffic is compounded by the fact that the number of vehicles and driven kilometres increase each year. Road traffic is one of the main sources of particulate matter and traffic volume is still increasing and has unpleasant impact on longevity of the pavements and the environment. Vehicle motions cause mechanical wearing of the asphalt pavement surface - wearing course by vehicle tyres. The contribution deals with abrasion of bituminous wearing courses of pavements. The asphalt mixtures of wearing courses are compared in terms of mechanically separated particulate matter. The samples of asphalt mixtures were rutted in wheel tracking machine. The particulate matter measurements were performed in laboratory conditions. The experimental laboratory measurements make it possible to sample particulates without contamination from exhaust emissions, abraded particles from vehicles, resuspension of road dust and climate affects. The contribution offers partial results of measurements on six trial samples of asphalt mixtures with different composition. It presents particulate matter morphology and the comparison of rutted asphalt samples in terms of PM mass concentrations and chemical composition.

  10. Laboratory Measurements of Particulate Matter Concentrations from Asphalt Pavement Abrasion

    Fullová Daša


    Full Text Available The issue of emissions from road traffic is compounded by the fact that the number of vehicles and driven kilometres increase each year. Road traffic is one of the main sources of particulate matter and traffic volume is still increasing and has unpleasant impact on longevity of the pavements and the environment. Vehicle motions cause mechanical wearing of the asphalt pavement surface - wearing course by vehicle tyres. The contribution deals with abrasion of bituminous wearing courses of pavements. The asphalt mixtures of wearing courses are compared in terms of mechanically separated particulate matter. The samples of asphalt mixtures were rutted in wheel tracking machine. The particulate matter measurements were performed in laboratory conditions. The experimental laboratory measurements make it possible to sample particulates without contamination from exhaust emissions, abraded particles from vehicles, resuspension of road dust and climate affects. The contribution offers partial results of measurements on six trial samples of asphalt mixtures with different composition. It presents particulate matter morphology and the comparison of rutted asphalt samples in terms of PM mass concentrations and chemical composition.

  11. Superficial characterization of titanium league when submitted to abrasive blasting; Caracterizacao superficial de titanio liga ao ser submetido a tratamento de jateamento

    Suzuki, L.Y.; Leite, I.V.; Szesz, E.M.; Siqueira, C.J.M., E-mail: [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil)


    Commercially pure titanium and some of its alloys exhibit a good biocompatibility. These characteristics are frequently used in the manufacture of orthopedic and dental implants. It is possible to modify its surface making it the bioactive using various methods, such as deposition of hydroxyapatite by plasma spray and increasing the roughness of the surface by abrasive blasting. This work is to modify the surface of titanium alloy Ti6Al4V ELI (ASTM F136: 02a) for abrasive blasting and study the morphology, crystallographic phases and the mechanical characteristics of the surface obtained. For such purpose, SEM images, diffraction of X-rays and tests of risk produced by nanoindenter. The sandblasting was done using alumina powder and blasting time of 6s. The morphology of the surfaces of Ti6Al4V ELI changed after sandblasting with increased roughness. It is possible to conclude that after sandblasting the titanium surface do not have a ductile behavior. (author)

  12. A light-scattering study of Al2O3 abrasives of various grit sizes

    Heinson, Yuli W.; Chakrabarti, Amitabha; Sorensen, Christopher M.


    We report light scattering phase function measurements for irregularly shaped Al2O3 abrasive powders of various grit sizes. Q-space analysis is applied to the angular scattering to reveal a forward scattering regime, Guinier regime, power law regime with quantifiable exponents, and an enhanced backscattering regime. The exponents of the power laws for Al2O3 abrasives decrease with increasing internal coupling parameter ρ ‧ , which is in agreement with previous observations for other irregular particles. Unlike other dust particles previously studied showing single power laws under Q-space analysis, the largest three abrasives, for which ρ ‧ ≳ 100 , showed a kink in the power law, which is possibly due to the higher degree of symmetry for the abrasives than for all the particles studied previously. Direct comparison of the 1200, 1000, and 800 grit abrasive scattering to scattering by corresponding spheres shows that the scatterings approximately coincide at the spherical particle qR ≃ ρ ‧ crossover point. Furthermore, the scattering at the maximum qR = 2 kR by the irregularly shaped abrasives is close to the geometric centers of the glories of the spheres.

  13. Abrasive Wear of Fe-Mn-Si-Cr-Ni Shape Memory Stainless Steel: Preliminary Results

    Silva, Christian Egidio Da; Bernardi, Heide Heloise; Otubo, Jorge


    This study was developed to understand the influence of chemical composition and austenitic grain size on the wear resistance in stainless shape memory steel. A two-body abrasive wear device was used to understand the wear mechanism involved. They were tested pins with the following chemical composition: Fe-10.3Mn-5.3Si-9.9Cr-4.9Ni-0.006C and Fe-14.2Mn-5.3Si-8.8Cr-4.6Ni-0.008C after being austenitized at 900 and 1050 °C, followed by water quenching. The surface characterization was performed by optical microscopy and scanning electron microscopy, and the roughness profile evaluation was also conducted. The weight loss was measured after conducting the wear testing, and the wear rates were estimated. The results demonstrated that the alloy with less manganese and higher chromium content has the best wear resistance (between 17.5 and 18.9%). With an increase of the austenitic grain size there was a small reduction on the wear resistance (between 3.0 and 4.1%). The chemical composition demonstrated to have higher influence on the wear behavior than the austenitic grain size.

  14. Abrasion, Erosion and Cavitation Erosion Wear Properties of Thermally Sprayed Alumina Based Coatings

    Ville Matikainen


    Full Text Available Thermally-sprayed alumina based materials, e.g., alumina-titania (Al2O3-TiO2, are commonly applied as wear resistant coatings in industrial applications. Properties of the coatings depend on the spray process, powder morphology, and chemical composition of the powder. In this study, wear resistant coatings from Al2O3 and Al2O3-13TiO2 powders were sprayed with plasma and high-velocity oxygen-fuel (HVOF spray processes. Both, fused and crushed, and agglomerated and sintered Al2O3-13TiO2 powders were studied and compared to pure Al2O3. The coatings were tested for abrasion, erosion, and cavitation resistances in order to study the effect of the coating structure on the wear behavior. Improved coating properties were achieved when agglomerated and sintered nanostructured Al2O3-13TiO2 powder was used in plasma spraying. Coatings with the highest wear resistance in all tests were produced by HVOF spraying from fused and crushed powders.

  15. Effect of ion nitriding on the abrasive wear resistance of ultrahigh-strength steels with different silicon contents

    Riofano, R. M. Muñoz; Casteletti, L. C.; Nascente, P. A. P.


    This article studies the effect of silicon (Si) on ultrahigh-strength AISI 4340 steels in connection with the thermal treatment, as well as the influence of this element on nitriding and, consequently, abrasive wear. Four alloys with different Si contents were nitrided at 350 °C (4 and 8 h) and 500 and 550 °C (2 and 4 h) in a gas mixture of 80 vol.% H2 and 20 vol.% N2. The nitrided layers were characterized by microhardness and pin-on-disk tests, optical microscopy, scanning electron microscopy with energy-dispersive x-ray spectrometry, and x-ray diffraction (XRD). The increase in Si enhanced the tempering resistance of the steels and also improved considerably the hardness of the nitrided layers. The increase in Si produced thinner compound layers with better hardness quality and high abrasive wear resistance. XRD analysis detected a mixture of nitrides in the layers γ‧-Fe4N, ɛ-Fe2 3N, CrN, MoN, and Si3N4 with their proportions varying with the nitriding conditions.

  16. Performance of Flame Sprayed Ni-WC Coating under Abrasive Wear Conditions

    Harsha, S.; Dwivedi, D. K.; Agarwal, A.


    This paper describes the influence of a post spray heat treatment on the microstructure, microhardness and abrasive wear behavior of the flame sprayed Ni-WC (EWAC 1002 ET) coating deposited on the mild steel. Coatings were deposited by using an oxy-acetylene flame spraying torch (Superjet Eutalloy L & T, India). The wear behavior of the coating was evaluated using a pin on disc wear system against SiC abrasive medium of 120 and 600 grades at 5, 10, 15, and 20 N normal load. Results revealed that the influence of normal load on wear is governed by the microstructure, hardness and abrasive grit size. The heat treatment increased average microhardness of the coating. However, it was found that the hardness does not correctly indicate the abrasive wear resistance of Ni-WC coating in an as sprayed and heat treated condition. The heat treatment of the coating improved its abrasive wear resistance against fine abrasive medium while the wear resistance against coarse abrasive was found to be a function of a normal load. At low-normal load (5 and 10 N) the heat treated coating showed lower-wear rate than as spayed coating while at high-normal loads (15 and 20 N) heat treated coating was subjected to higher-wear rate than as sprayed coating. In general, an increase in normal load increased the wear rate. The scanning electron microscopy study indicated that the wear largely takes place by groove formation and scoring of eutectic matrix and the fragmentation of the carbide particles.

  17. Analytical method for softness abrasive flow field based on discrete phase model


    Aiming at the problem of difficult contact finishing for mini structural surface in course of mould manufacturing,a new no-tool precision machining method based on soft abrasive flow machining (SAFM) was proposed. It allocated restrained component near surface machined,constituted restrained abrasive flow passage,and made the surface become a segment of passage wall. It could control turbulence abrasive flow in restrained passage,realize micro cutting for passage wall,and utilize the irregular motion of abrasive flow to eliminate the mono-directional marks on machined surfaces,and the precision could reach the specular level. A two-phase dynamic model of abrasive flow oriented to SAFM combined with discrete phase model (DPM) was established,the law of two-phase flow motion and the related physical parameters was obtained by corresponding numerical simulation method,and the mechanism of precision machining in SAFM was discussed. Simulation results show that the abrasive flow machining process mainly appears as translation of ablating location with the influence by granular pressure,and as the variation of machining efficiency with the influence by near-wall particle velocity. Thus via control of the inlet velocity and its corresponding machining time,it is supposed to work out the machining process according to the machining requirements by using the Preston equation to seek the relationship among velocity,pressure and material removing rate. By tracking near-wall particles,it can be confirmed that the movement of near-wall abrasive particles is similar to stream-wise vortices. The cutting traces on workpiece surfaces assume disorderly arrangement,so the feasibility of the SAFM method can be reaffirmed.

  18. Multiphase Flow and Wear in the Cutting Head of Ultra-high Pressure Abrasive Water Jet

    YANG Minguan; WANG Yuli; KANG Can; YU Feng


    Abrasive water jet cutting technology is widely applied in the materials processing today and attracts great attention from scholars, but many phenomena concerned are not well understood, especially in the internal jet flow of the cutting head at the condition of ultra-high pressure. The multiphase flow in the cutting head is numerically simulated to study the abrasive motion mechanism and wear inside the cutting head at the pressure beyond 300 Mpa. Visible predictions of the particles trajectories and wear rate in the cutting head are presented. The influences of the abrasive physical properties, size of the jewel orifice and the operating pressure on the trajectories are discussed. Based on the simulation, a wear experiment is carried out under the corresponding pressures. The simulation and experimental results show that the flow in the mixing chamber is composed of the jet core zone and the disturbance zone, both affect the particles trajectories. The mixing efficiency drops with the increase of the abrasive granularity. The abrasive density determines the response of particles to the effects of different flow zones, the abrasive with medium density gives the best general performance. Increasing the operating pressure or using the jewel with a smaller orifice improves the coherency of particles trajectories but increases the wear rate of the jewel holder at the same time. Walls of the jewel holder, the entrance of the mixing chamber and the convergence part of the mixing tube are subject to wear out. The computational and experimental results give a qualitative consistency which proves that this numerical method can provide a reliable and visible cognition of the flow characteristics of ultra-high pressure abrasive water jet. The investigation is benefit for improving the machining properties of water jet cutting systems and the optimization design of the cutting head.

  19. Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion

    Kim, Chang-Lae; Kim, Dae-Eun


    A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature.

  20. Self-healing Characteristics of Collagen Coatings with Respect to Surface Abrasion.

    Kim, Chang-Lae; Kim, Dae-Eun


    A coating based on collagen with self-healing properties was developed for applications in mechanical components that are prone to abrasion due to contact with a counter surface. The inherent swelling behavior of collagen in water was exploited as the fundamental mechanism behind self-healing of a wear scar formed on the surface. The effects of freeze-drying process and water treatment of the collagen coatings on their mechanical and self-healing properties were analyzed. Water was also used as the medium to trigger the self-healing effect of the collagen coatings after the wear test. It was found that collagen coatings without freeze-drying did not demonstrate any self-healing effect whereas the coatings treated by freeze-drying process showed remarkable self-healing effect. Overall, collagen coatings that were freeze-dried and water treated showed the best friction and self-healing properties. Repeated self-healing ability of these coatings with respect to wear scar was also demonstrated. It was also confirmed that the self-healing property of the collagen coating was effective over a relatively wide range of temperature.

  1. Effect of Intercritical Heat Treatment on the Abrasive Wear Behaviour of Plain Carbon Dual Phase Steel

    Manoj, M. K.; Pancholi, V.; Nath, S. K.

    Dual phase (DP) steels have been prepared from low carbon steel (0.14% C) at intercritical temperature 740°C and time is varied from 1 minute to 30 minutes followed by water quenching. These steels have been characterized by optical microscopy, FE-SEM, hardness measurements, tensile properties and electron backscattered diffraction (EBSD) studies. Tensile properties of a typical dual phase steel are found to be 805 MPa ultimate tensile strength with 18% total elongation. Martensite volume fraction of D P steel (determined by EBSD technique) prepared at 740°C for 6 minutes is found to be 10.2% and the grain size of ferrite and martensite found to be 14.39 micron and 1.05 microns respectively. Abrasive wear resistance of dual phase steels has been determined by pin on drum wear testing machine. DP steels have been found to be 25% more wear resistant than that of normalized steel. Short intercritical heating time followed by water quenching gives higher wear resistance by virtue of smaller and well dispersed martensite island in the matrix of ferrite.

  2. Mechanical Properties and Corrosion-Abrasion Wear Behavior of Low-Alloy MnSiCrB Cast Steels Containing Cu

    Luo, Kaishuang; Bai, Bingzhe


    Two medium carbon low-alloy MnSiCrB cast steels containing different Cu contents (0.01 wt pct and 0.62 wt pct) were designed, and the effect of Cu on the mechanical properties and corrosion-abrasion wear behavior of the cast steels was studied. The results showed that the low-alloy MnSiCrB cast steels obtained excellent hardenability by a cheap alloying scheme. The microstructure of the MnSiCrB cast steels after water quenching from 1123 K (850 °C) consists of lath martensite and retained austenite. After tempering at 503 K (230 °C), carbides precipitated, and the hardness of the cast steels reached 51 to 52 HRC. The addition of Cu was detrimental to the ductility and impact toughness but was beneficial to the wear resistance in a corrosion-abrasion wear test. The MnSiCrB cast steel with Cu by the simple alloying scheme and heat treatment has the advantages of being high performance, low cost, and environmentally friendly. It is a potential, advanced wear-resistant cast steel for corrosion-abrasion wear conditions.

  3. In vitro toothbrushing abrasion of dental resin composites: packable, microhybrid, nanohybrid and microfilled materials

    Rafael Ratto de Moraes


    Full Text Available This study evaluated weight loss and surface roughening after toothbrushing of different resin composites: one packable (Solitaire 2, Heraeus Kulzer, one microhybrid (Charisma, Heraeus Kulzer, one nanohybrid (Simile, Pentron and one microfilled (Durafill VS, Heraeus Kulzer. Cylindrical specimens (n = 20 were prepared. Half of the samples were submitted to 60,000 strokes, at 4 Hz, with a dentifrice-water slurry. Control samples (n = 10 remained stored at 37°C. Pre- and post-abrasion parameters for weight (mg and surface roughness (Ra, µm were determined on an analytical balance and a surface profilometer. Data were separately submitted to Repeated Measures ANOVA and Tukey's test (a = 0.05. Percentages of weight loss were analyzed by ANOVA and Tukey's test (a = 0.05. The relationship between both evaluations was assessed by Pearson's test (a = 0.05. The means (% for weight loss (standard deviation were 0.65(0.2, 0.93(0.2, 1.25(0.6 and 1.25(0.4 for Simile, Durafill, Charisma and Solitaire, respectively. Baseline roughness means ranged from 0.065(0.01, 0.071(0.01, 0.066(0.02 and 0.074(0.01 for Simile, Durafill, Charisma and Solitaire, respectively, to 0.105(0.04, 0.117(0.03, 0.161(0.03 and 0.214(0.07 after testing. The composites with larger fillers presented higher weight loss and roughening than the finer materials (p < 0.05. For both evaluations, control specimens showed no significant alteration. No significant relationship between loss of weight and roughness alteration was detected (r = 0.322, p = 0.429.

  4. Optimization MRR Of Stainless Steel 403 In Abrasive Water Jet Machining UsingAnova And Taguchi Method



    Full Text Available Stainlesssteel 403 is high-alloysteelwith good corrosion resistance and it’svery hard material. Abrasive water jet is an effective method for machining, cutting and drilling of stainlesssteel 403. In thispaperweoptimize the metalremoval rate of stainlesssteel 403 in abrasive water jet machining. The MRRisoptimize by usingthreeparameters water pressure, abrasive flow rate and stand-off distance and L9 orthogonal array of Taguchimethod use to analyse the result. 9 experimentalrunsbased on L9 orthogonal array of Taguchimethod.

  5. 喷涂型聚氨酯弹性体耐磨材料主要性能表征及影响因素分析%Performance Characterization and Influencing Factors Analysis of Spraying Abrasion-Resistance Polyurethane Elastomer

    孟庆莉; 崔洪犁; 吴文文; 刘东晖


    The component A was synthesized by MDI and polyether polyol. The component B was composed by PPG, PTMG, diamine extender chain agent, abrasion⁃resisting additive, etc. Abrasion resistance polyurethane e⁃lastomer coating was prepared with component A and B by special spraying equipment. The effects of different poly⁃ether polyols and abrasion resisting additives on polyurethane elastomer coating were discussed. The four test meth⁃ods of spraying abrasion⁃resistance polyurethane elastomer under dry experimental conditions were introduced, in⁃cluding Akron abrasion, DIN abrasion, Taber abrasion and NBS abrasion. The relationship between these four kinds of abrasion was explained by experimental data. The abrasion⁃resisting additive A could reduce coefficient of friction obviously, the coefficient of kinetic friction was 0�321. PTMG could mostly improve the abrasion⁃resistance per⁃formance of spraying polyurethane elastomer coating, the Akron abrasion value was 0�030 cm3 .%采用二苯基甲烷二异氰酸酯和聚醚多元醇为原料反应制备A组分,聚醚多元醇、二胺扩链剂和耐磨助剂等混合制备B组分;A、B组分通过专用喷涂设备制备了聚氨酯弹性体耐磨涂层。讨论了聚醚多元醇和耐磨助剂的种类对弹性体涂层耐磨性能的影响,以及实验室干态下Akron磨耗、DIN磨耗、Taber磨耗和NBS磨耗4种磨耗之间的关系。结果表明,增滑助剂A的应用显著降低了喷涂型聚氨酯弹性体涂层的表面摩擦系数,测得动摩擦系数为0�321;聚四氢呋喃醚二醇的应用显著提高了喷涂型聚氨酯弹性体涂层的耐磨性能,测得Akron磨耗为0�030 cm3。

  6. Emission factors and source apportionment for abrasion particles produced by road traffic

    Bukowiecki, N.; Lienemann, P.; Figi, R.; Hill, M.; Richard, A.; Furger, M.; Rickers, K.; Cliff, S. S.; Baltensperger, U.; Gehrig, R.


    Particle emissions of road traffic are generally associated with fresh exhaust emissions only. However, recent studies identified a clear contribution of non-exhaust emissions to the PM10 load of the ambient air. These emissions consist of particles produced by abrasion from brakes, road wear, tire wear, as well as resuspension of deposited road dust. For many urban environments, quantitative information about the contributions of the individual abrasion processes is still scarce. For effective PM10 reduction scenarios it is of particular interest to know whether road wear, resuspension or fresh abrasion from vehicles is dominating the non-exhaust PM10 contribution. In Switzerland, the emissions of road traffic abrasion particles into the ambient air were characterized in the project APART (Abrasion Particles produced by Road Traffic). The project aimed at finding the contribution of the non-exhaust sources to total traffic-related PM10 and PM2.5 for different traffic conditions, by determining specific elemental fingerprint signatures for the various sources. This was achieved by hourly elemental mass concentration measurements in three size classes (2.5-10, 1-2.5 and 0.1-1 micrometers) with a rotating drum impactor (RDI) and subsequent synchrotron radiation X-ray fluorescence spectrometry (SR-XRF). The elemental fingerprint measurements were embedded into a large set of aerosol, gas phase, meteorological and traffic count measurements. To identify traffic related emissions, measurements were performed upwind and downwind of selected roads. For a better investigation of road wear, a road wear simulator was applied in additional experiments. This allows for the identification and quantification of the different source contributions by means of source-receptor modeling, and for the calculation of real-world emission factors for the individual abrasion sources. The preliminary analysis of hourly resolved trace element measurements in a street canyon in Zürich showed

  7. Hybrid layer thickness and morphology: Influence of cavity preparation with air abrasion.

    Barceleiro, Marcos Oliveira; de Mello, Jose Benedicto; Porto, Celso Luis de Angelis; Dias, Katia Regina Hostilio Cervantes; de Miranda, Mauro Sayao


    Dentinal surfaces prepared with air abrasion have considerably different characteristics from those prepared with conventional instruments. Different hybrid layer morphology and thickness occur, which can result in differences in the quality of restorations placed on dentinal surfaces prepared with a diamond bur compared to surfaces prepared using air abrasion. The objective of this study was to compare the hybrid layer thickness and morphology formed utilizing Scotchbond Multi-Purpose Plus (SBMP) on dentin prepared with a diamond bur in a high-speed handpiece and on dentin prepared using air abrasion. Flat dentin surfaces obtained from five human teeth were prepared using each method, then treated with the dentin adhesive system according to manufacturer's instructions. After a layer of composite was applied, specimens were sectioned, flattened, polished, and prepared for scanning electron microscopy. Ten different measurements of hybrid layer thickness were obtained along the bonded surface in each specimen. SBMP produced a 3.43 ± 0.75 µm hybrid layer in dentin prepared with diamond bur. This hybrid layer was regular and found consistently. In the air abrasion group, SBMP produced a 4.94 ± 1.28 µm hybrid layer, which was regular and found consistently. Statistical ANOVA (P = 0.05) indicated that there was a statistically significant difference between the groups. These data indicate that the air abrasion, within the parameters used in this study, provides a thick hybrid layer formation.

  8. Projectile Nose Mass Abrasion of High-Speed Penetration into Concrete

    Haijun Wu


    Full Text Available Based on the dynamic spherical cavity expansion theory of concrete and the analysis of experimental data, a mass abrasion model of projectile considering the hardness of aggregates, the relative strength of target and projectile, and the initial impact velocity is constructed in this paper. Furthermore, the effect of mass abrasion on the penetration depth of projectile and the influence of hardness of aggregates and strength of projectile on penetration depth and mass loss are also analyzed. The results show that, for the ogive-nose projectile with the CRH of 3 and aspect ratio of 7 penetrating the concrete of 35 MPa, the “rigid-body penetration” model is available when the initial impact velocity is lower than 800 m/s. However, when the initial impact velocity is higher than 800 m/s, the “deforming/eroding body penetration” model should be adopted. Through theoretical analysis and numerical calculation, the results indicate that the initial impact velocity is the most important factor of mass abrasion. The hardness of aggregates and the strength of projectile are also significant factors. But relatively speaking, the sensitivity of strength of projectile to mass abrasion is higher, which indicates that the effect of projectile material on mass abrasion is more dramatic than the hardness of aggregates.

  9. Abrasion of human enamel by brushing with a commercial dentifrice containing hydroxyapatite crystals in vitro.

    Kodaka, T; Kobori, M; Hirayama, A; Abe, M


    Automatic toothbrushing with a commercial dentifrice containing hydroxyapatite (HAP) crystals was performed on the tangential polished surfaces of sound human enamel, mainly consisting of biological apatite similar to HAP, for 10 min in vitro. The X-ray diffraction peaks of HAP, brushite (DCPD), and monetite (DCP) crystals were detected from the dentifrice. After brushing, the enamel surfaces were observed with a scanning electron and a confocal scanning laser microscope. The brushing caused larger abrasive loss and more remarkable roughness of the enamel surfaces following the broad traces of brush bristles and the exposure of prism structures than brushing with a dentifrice containing only DCPD, which we previously reported. We claim that the fine granular-shaped HAP crystals of the dentifrice indicated as an active ingredient for preventing enamel caries possess stronger abrasivity of sound enamel than the DCPD and DCP as abrasives on account of their Mohs hardness values rather than sizes and shapes. The HAP crystals of dentifrices may not occlude the small defects of early caries enamel, but erode them more strongly as an abrasive than the other abrasives.

  10. Finishing of display glass for mobile electronics using 3M Trizact diamond tile abrasive pads

    Zheng, Lianbin; Fletcher, Tim; Na, Tee Koon; Sventek, Bruce; Romero, Vince; Lugg, Paul S.; Kim, Don


    This paper will describe a new method being used during the finishing of glass displays for mobile electronics including mobile hand held devices and notebook computers. The new method consists of using 3M TrizactTM Diamond Tile Abrasive Pads. TrizactTM Diamond Tile is a structured fixed abrasive grinding technology developed by 3M Company. The TrizactTM Diamond Tile structured abrasive pad consists of an organic (polymeric binder) - inorganic (abrasive mineral, i.e., diamond) composite that is used with a water-based coolant. TrizactTM Diamond Tile technology can be applied in both double and single side grinding applications. A unique advantage of TrizactTM Diamond Tile technology is the combination of high stock removal and low sub-surface damage. Grinding results will be presented for both 9 micron and 20 micron grades of TrizactTM Diamond Tile abrasive pads used to finish several common display glasses including Corning GorillaTM glass and Soda Lime glass.

  11. Assessment of mechanical and three-body abrasive wear peculiarity of TiO$_2$- and ZnO-filled bi-directional E-glass fibre-based polyester composites



    This paper is about the development of bi-directional E-glass fibre-based polyester composites filled with zinc oxide (ZnO) and titanium dioxide (TiO$_2$) fillers, respectively. The mechanical characterization of these composites is performed. The three-body abrasive wear characteristic of fabricated composites has been assessed under different operating conditions. For this, the three-body abrasion test is done on dry abrasion test rig (TR-50)and analysed using Taguchi’s experimental design scheme and analysis of variance. The results obtained from these experiments are also validated against existing microscopic models of Ratner–Lancaster and Wang. A good linear relationship is obtained between specific wear rate and the reciprocal of ultimate strength and strain at tensile fracture of these composites. It indicates that the experimentally obtained results are in good agreement with theseexisting models. It is found that the tensile strength decreases with filler loading, while hardness, flexural strength, inter-laminar shear strength and impact strength are increased. TiO$_2$-filled composites were observed to performbetter than ZnO-filled composites under abrasive wear situations. The wear mechanism is studied in correlation with the SEM micrograph of the worn-out surface of composites. Performance optimization of composites is doneby using VIKOR method.

  12. Structural transformations in wear resistance of iron- and cobalt-based amorphous alloys during abrasive wear

    Korshunov, L. G.; Shabashov, V. A.; Chernenko, N. L.


    The wear resistance and structural changes in a number of amorphous alloys based on iron and cobalt and in high-carbon tool steels are studied during wear by a fixed abrasive (crondum, Carborundum) at room temperature and -196°C. The abrasive wear resistance of the amorphous alloys is shown to be 1.6-3.1 lower than that of the high-carbon tool steels having a similar hardness. The relatively low level of the abrasive wear resistance of the amorphous alloys is assumed to be caused by strain softening of their surface during wear. A nanocrystalline structure is found to form in local microvolumes in a thin deformed surface layer of the alloys.

  13. Evaluation of subsurface damage in GaN substrate induced by mechanical polishing with diamond abrasives

    Aida, Hideo, E-mail: [NJC Institute of Technology, Namiki Precision Jewel Co., Ltd., 3-8-22 Shinden, Adachi, Tokyo 123-8511 (Japan); KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan); Takeda, Hidetoshi; Kim, Seong-Woo; Aota, Natsuko; Koyama, Koji [NJC Institute of Technology, Namiki Precision Jewel Co., Ltd., 3-8-22 Shinden, Adachi, Tokyo 123-8511 (Japan); Yamazaki, Tsutomu; Doi, Toshiro [KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)


    The relationship between the depth of the subsurface damage (SSD) and the size of the diamond abrasive used for mechanical polishing (MP) of GaN substrates was investigated in detail. GaN is categorized as a hard, brittle material, and material removal in MP proceeds principally to the fracture of GaN crystals. Atomic force microscopy and cathodoluminescence imaging revealed that the mechanical processing generated surface scratches and SSD. The SSD depth reduced as the diamond abrasive size reduced. A comparison of the relationship between the SSD depth and the diamond abrasive size used in the MP of GaN with the same relationship for typical brittle materials such as glass substrates suggests that the MP of GaN substrates proceeds via the same mechanism as glass.

  14. The rock abrasion record at Gale Crater: Mars Science Laboratory results from Bradbury Landing to Rocknest

    Bridges, N.T.; Calef, F.J.; Hallett, B.W.; Herkenhoff, Kenneth E.; Lanza, N.L.; Le Mouélic, S.; Newman, C.E.; Blaney, D.L.; de Pablo, M.A.; Kocurek, G.A.; Langevin, Y.; Lewis, K.W.; Mangold, N.; Maurice, S.; Meslin, P.-Y.; Pinet, P.; Renno, N.O.; Rice, CM.S.; Richardson, M.E.; Sautter, V.; Sletten, R.S.; Wiens, R.C.; Yingst, R.A.


    Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from submillimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high-speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

  15. An Investigation on a Tin Fixed Abrasive Polishing Pad with Phyllotactic Pattern for Polishing Wafer

    吕玉山; 刘电飞; 寇智慧


    In order to improve the polishing ability of polishing pads, a kind of polishing pad with the tin fixed abrasive blocks, which are arranged based on the phyllotaxis theory of biology, was designed and fabricated by the use of electroplating technology, and also its polishing ability for JGS-2 wafer was investigated by polishing experiments. The research resuits show that the phyllotactic parameters of the polishing pad influence the arrangement density of the tin fixed abrasive blocks, the polishing pad with phyllotactic pattern is feasibly fabricated by the use of electroplating technology, and the good polishing result can be obtained by using the polishing pad with pbyllotactic pattern to polish a wafer when the diameter D of the tin fixed abrasive block is between Φ. 3 mm and Φ1. 4 mm, and the phyllotactic coefficient k between 1.0 and 1.1, respectively.

  16. Understanding Characteristic of Abrasion of Refractory Lining Caused by Bath Oscillation in BOF Steelmaking

    Li, Qiang; Li, Mingming; Kuang, S. B.; Zou, Zongshu


    This paper presents a numerical study of the refractory abrasion occurring widely inside basic oxygen furnace (BOF) steelmaking. The mechanism of refractory abrasion is examined numerically referring to the bath oscillation with regard to flows, turbulence and wall shear stress inside a BOF. The simulation results reveal that the refractory abrasion tends to occur on the wall region between the slag/atmosphere and slag/metal interfaces due to the oscillation of the bath in the blowing process, which generally promotes slag-line erosion. The decreased nozzle angle, and either increased lance height or operation pressure can lead to more serious refractory erosion that occurs more likely during the slag-making period in the operation of BOF.

  17. A Review on Current Research and Development in Abrasive Waterjet Machining

    M. M. Korat


    Full Text Available Abrasive waterjet machining (AWJM is an emerging machining technology option for hard material parts that are extremely difficult-to-machine by conventional machining processes. A narrow stream of high velocity water mixed with abrasive particles gives relatively inexpensive and environment friendly production with reasonably high material removal rate. Because of that abrasive waterjet machining has become one of the leading manufacturing technologies in a relatively short period of time. This paper reviews the research work carried out from the inception to the development of AWJM within the past decade. It reports on the AWJM research relating to improving performance measures, monitoring and control of process, optimizing the process variables. A wide range of AWJM industrial applications for different category of material are reported with variations. The paper also discusses the future trend of research work in the same area.

  18. Energy Consumption in Comminution of Mica with Cavitation Abrasive Water Jet

    GUO Chu-wen; DONG Lu


    We have studied the efficiency of energy consumption in the comminution of mica powder with cavitation abrasive water jet technology. The energy required to create new surfaces in the comminution of mica powder with cavitation abrasive water jet was calculated, in order to estimate its efficiency of energy consumption. The particle size distribution and the specific surface area were measured by applying a JEM-200CX transmission electron microscope and an Autosorb-1 automatic surface area analyzer. The study results show that the efficiency of energy consumed in creating new surface areas is as high as 2.92%, or 4.94% with the aid of cavitation in the comminution of mica powder. This efficiency will decrease with an increase in the number of comminutions. After three comminutions, the efficiencies will become 1.91% and 2.29% for comminution without cavitation and with cavitation, respectively. The abrasive water jet technology is an effective way for comminution of mica powder.

  19. [Evaluation of potential risks of abrasive water jet osteotomy in-vivo].

    Kuhlmann, C; Pude, F; Bishup, C; Krömer, S; Kirsch, L; Andreae, A; Wacker, K; Schmolke, S


    Since the 80's the water jet scalpel is an established tool in some surgical fields. It is used in particular in visceral surgery for preparation of parenchymatous organs. By the addition of biocompatible abrasives, this technique is able to effectively machine hard biological tissues. Free defined cutting geometries can be realised in a non contact process. Therewith this method has crucial advantages compared to conventional osteotomy techniques and gives new impulses to the development in endoprosthetics and correction osteotomies of hollow bones. In the presented work the new developed abrasive water injection jet (AWIJ) was used the first time for in-vivo osteotomies. Aim of this study was the detection of potential thrombembolic effects and wash in effects of the cutting fluid. Hollow bones of the fore and hind leg of 20 house pigs were treated with the new cutting technique. Intraoperative documentation of relevant vital parameters was performed by a multi monitoring system. Thrombembolic effects during the osteotomy were detected by transthoracic Doppler ultrasonography and transesophagale echocardiography. The hollow bones were prepared in consideration of the vascularisation's protection especially in respect to the venous flow. Thrombembolic effects with temporary haemodynamic respectively respiratory consequences could be detected exclusively by using the so called "3-component jet", which consists of 90 vol % of air. The usage of an abrasive suspension enables the airfree dosing of dry soluable abrasives. Thrombembolic effects could not be monitored in this case. Intramedullary fluid in-wash effects as well as resulting electrolytic disorders could not be proven. For abrasive waterjet osteotomies with 3 component jet a relevant risk of thrombembolic effects could be shown. This knowledge has also to be considered for abdominal and neurosurgical applications in the future. Due to the usage of an abrasive suspension this risk can fully be avoided.

  20. Randomised in situ study on the efficacy of a tin/chitosan toothpaste on erosive-abrasive enamel loss.

    Schlueter, N; Klimek, J; Ganss, C


    Tin is a notable anti-erosive agent, and the biopolymer chitosan has also shown demineralisation-inhibiting properties. Therefore, the anti-erosive/anti-abrasive efficacy of the combination of both compounds was tested under in situ conditions. Twenty-seven volunteers were included in a randomised, double-blind, three-cell crossover in situ trial. Enamel specimens were recessed on the buccal aspects of mandibular appliances, extraorally demineralised (6 × 2 min/day) and intraorally treated with toothpaste slurries (2 × 2 min/day). Within the slurry treatment time, one-half of the specimens received additional intraoral brushing (5 s, 2.5 N). The tested toothpastes included a placebo toothpaste, an experimental NaF toothpaste (1,400 ppm F(-)) and an experimental F/Sn/chitosan toothpaste (1,400 ppm F(-), 3,500 ppm Sn(2+), 0.5% chitosan). The percentage reduction of tissue loss (slurry exposure/slurry exposure + brushing) compared to placebo was 19.0 ± 47.3/21.3 ± 22.4 after use of NaF and 52.5 ± 30.9/50.2 ± 34.3 after use of F/Sn/chitosan. F/Sn/chitosan was significantly more effective than NaF (p ≤ 0.001) and showed good efficacy against erosive and erosive-abrasive tissue loss. This study suggests that the F/Sn/chitosan toothpaste could provide good protection for patients who frequently consume acidic foodstuffs.

  1. High Speed Lapping of SiC Ceramic Material with Solid (Fixed) Abrasives

    ZHANG Wei; YANG Xin-hong; SHANG Chun-min; HU Xiao-yong; HU Zhong-hui


    An experimental investigation is carried out to machine SiC ceramic material through the method of high speed plane lapping with solid(fixed) abrasives after the critical condition of brittle-ductile transition is theoretically analyzed. The results show that the material removal mechanism and the surface roughness are chiefly related to the granularity of abrasives for brittle materials such as SiC ceramic. It is easily realized to machine SiC ceramic in the ductile mode using W3.5 grit and a high efficiency, low cost and smooth surface with a surface roughness of Ra 2.4nm can be achieved.

  2. Methods for atomistic abrasion simulations of laterally periodic polycrystalline substrates with fractal surfaces

    Eder, S. J.; Bianchi, D.; Cihak-Bayr, U.; Gkagkas, K.


    In this work we discuss a method to generate laterally periodic polycrystalline samples with fractal surfaces for use in molecular dynamics simulations of abrasion. We also describe a workflow that allows us to produce random lateral distributions of simple but realistically shaped hard abrasive particles with Gaussian size distribution and random particle orientations. We evaluate some on-the-fly analysis and visualization possibilities that may be applied during a molecular dynamics simulation to considerably reduce the post-processing effort. Finally, we elaborate on a parallelizable post-processing approach to evaluating and visualizing the surface topography, the grain structure and orientation, as well as the temperature distribution in large atomistic systems.

  3. ANN & ANFIS Models for Prediction of Abrasive Wear of 3105 Aluminium Alloy with Polyurethane Coating

    H. Alimam


    Full Text Available The quest for safety and reliability has increased significantly after Industrial revolution, so is the case for coating industries. In this paper 3105 Aluminium alloy sheet is coated with organic polyurethane coating. After the implementation of coating, various processes are undergone to check its reliability under elevated conditions. ANN & ANFIS model were developed and trained with an objective to find abrasive wear during the process. ANN & ANFIS model were compared with the experimental results. It is observed that the abrasive wear of a coated specimen can be predicted accurately and precisely using ANN and ANFIS models.

  4. Water jet and abrasive water jet cutting of unidirectional graphite/epoxy composite

    Ramulu, M.; Arola, D.


    Unidirectional graphite/epoxy composite material has been machined by water jet and abrasive water jet cutting processes. Topography and morphology of the machined surfaces were evaluated with surface profilometry and scanning electron microscopy. The surface characteristics in terms of roughness and the micromechanisms of material removal for both processes were analyzed and compared. Abrasive water jet surface characteristics of graphite/epoxy were found to be significantly different from those of the water jet cutting process and micromechanical behavior of material removal was strongly dependent on the fiber orientation.

  5. Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion

    Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina


    The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, m...

  6. Development and validation of an alternative disturbed skin model by mechanical abrasion to study drug penetration

    P. Schlupp


    Skin permeation of the three substances was increased in tape-stripped and abraded skin compared to untreated skin due to the reduced barrier integrity. Enhancement of drug uptake was highest for the most hydrophilic substance, caffeine, followed by sorbic acid and lipophilic testosterone. No significant difference in drug uptake studies was observed between the new abrasion method with an aluminum-coated sponge and the tape-stripping method. The obtained results demonstrate that this abrasion method is an alternative way to achieve a disturbed skin barrier for drug and chemical uptake studies.

  7. Toothbrush abrasivity in a long-term simulation on human dentin depends on brushing mode and bristle arrangement


    Objective The aim of this study was to evaluate the susceptibility of dentin to brushing abrasion using four different toothbrushes (rotating-oscillating, sonic and two types of manual toothbrushes) with the same brushing forces. Methods Dentin samples (n = 72) were selected from 72 impacted third molars. Half of the surface of dentin samples was covered with an adhesive tape, creating a protected and a freely exposed area in the same specimen. Brushing was performed with either a: sonic (Sonicare PowerUp, Philips GmbH, Hamburg, Germany), b: oscillating-rotating (Oral B Vitality Precisions Clean, Procter & Gamble, Schwalbach am Taunus, Germany) or two different manual toothbrushes c: flat trim brush head toothbrush (Dr. Best: Original, Glaxo-Smith-Kline, Bühl, Germany) and d: rippled-shaped brush head toothbrush (Blend-a-Dent, Complete V-Interdental, Blend-a-med, Schwalbach, Germany) in a custom made automatic brushing machine. The brushing force was set to 2 N and a whitening toothpaste (RDA = 150) was used. The simulation period was performed over a calculated period to mimic a brushing behavior of two times a day brushing for eight years and six months. Dentin loss was quantitatively determined by profilometry and statistically analyzed by Wilcoxon and Mann-Whitney-U Test (p < 0.05). Results The mean (standard deviation) surface loss was 21.03 (±1.26) μm for the sonic toothbrush, 15.71 (±0.85) μm for the oscillating-rotating toothbrush, 6.13 (±1.24) μm for the manual toothbrush with flat trim brush head and 2.50 (±0.43) μm for the manual toothbrush with rippled-shaped brush head. Differences between all groups were statistically significant at p<0.05. Conclusion Using the same brushing force and a highly abrasive toothpaste, manual toothbrushes are significantly less abrasive compared to power toothbrushes for an 8.5—year simulation. PMID:28222156

  8. Preparation of composite abrasives by electrostatic self-assembly method and its polishing properties in Cu CMP

    Huang Yishen; Xu Xuefeng; Yao Chunyan; Hu Jiande; Peng Wei


    The adsorption characteristics of cationic polyelectrolyte poly dimethyl diallyl ammonium chloride (PDADMAC) and anionic polyelectrolyte poly (sodium-p-styrenesulfonate) (PSS) on benzoguanamine formal-dehyde (BGF) particles are investigated. The charging characteristics of BGF particles are changed and con-trolled using electrostatic self-assembly method. A variety of PEi-BGF/SiO2 composite abrasives are obtained. The as-prepared samples are analyzed by zeta potential analysis,transmission electron microscope (TEM) and thermogravimetric (TG) analysis. The composite abrasive slurries are prepared for copper polishing. The poli-shing results indicate that it is SiO2 abrasives,not only coated SiO2 abrasive on polymer particles but also free SiO2 abrasive in slurry ,that offer the polishing action. The material removal rates of copper polishing are 264 nm/min,348 nm/min and 476 nm/min using single SiO2 abrasive slurry,PE0-BGF/SiO2 mixed abrasive slur-ry and PE3-BGF/SiO2 composite abrasive slurry,respectively. The surface roughness Ra of copper wafer (with 5μm× 5μm district) is decreased from 0.166μm to 3.7 nm,2.6 nm and 1.5 nm,and the surface peak-valley values Rpv are less than 20 nm,14 nm and 10 nm using these kinds of slurries,respectively.

  9. Synergetic effect of organic cores and inorganic shells for core/shell structured composite abrasives for chemical mechanical planarization

    Chen, Yang, E-mail: [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Li, Zhina [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Miao, Naiming [School of Mechanical Engineering, Changzhou University, Changzhou, Jiangsu 213016 (China)


    Highlights: • The damage-free polishing mechanism of core/shell composite abrasive was explored. • The organic core is help to decrease surface roughness and mechanical damages. • The inorganic shell is in favor of improving material removal rate. • The enhanced CMP behavior is due to the synergistic effect between core and shell. - Abstract: Core/shell structured organic/inorganic composite microspheres has an important potential application in efficient and damage-free chemical mechanical planarization/polishing (CMP) as a kind of novel abrasive due to its uniform non-rigid mechanical property. However, the synergistic effect of material removal between organic cores and inorganic shells of composite abrasives is ambiguous. In this work, oxide-CMP performances of various slurries, containing polystyrene (PS) spheres, solid abrasives (SiO{sub 2} or CeO{sub 2}), mixed abrasives ((PS + SiO{sub 2}) or (PS + CeO{sub 2})), core/shell composites (PS/SiO{sub 2} or PS/CeO{sub 2}), were investigated by atomic force microscopy. Experiment results indicated that the surfaces polished by composite abrasives exhibited lower surface roughness, fewer scratches as well as lower topographical variations than those by other type of abrasives. The core/shell structure of composite abrasives plays an important role in improving CMP behavior. Moreover, the organic cores are mainly beneficial to decrease surface roughness and mechanical damages, and the inorganic shells are in favor of improving material removal rate.

  10. On the abrasion of heat-treated 2.8C21Cr1Mo white cast iron

    Al-Rubaie, Kassim S.; Preti, Orlando [Centro Universitario SOCIESC, Joinville (Brazil). Engenharia Mecanica; Pohl, Michael [Bochum Univ. (Germany). Inst. fuer Werkstoffe


    The abrasion behaviour of heat-treated 2.8C21Cr1Mo cast iron was studied. The specimens were destabilised at two temperatures, 980 and 1050 C, for 4 h, air hardened, and then tempered at five temperatures, 220, 320, 400, 500, and 620 C, for 2 h followed by air cooling. Using a pin-on-plate abrasion apparatus, the specimens were abraded on four types of bonded abrasives (silicon carbide, corundum, flint, and glass). The effect of work hardening on the abrasion resistance was investigated. It was found that the increase in alloy hardness produced by heat treatment had little effect on the abrasion resistance against silicon carbide or corundum; the inverse was true against flint or glass. The as-hardened structure containing 40% retained austenite gave the best abrasion resistance, whereas the hardened and tempered at 620 C showed the worst. Both bulk hardness and matrix hardness before wear correlated poorly with the abrasion resistance. Therefore, a general model ''equivalent hardness'' was developed, in which the hardness of the abraded matrix was considered. With this model, the abrasion behaviour can be clearly analysed.

  11. Impact of Abrasion on Mass Loss and Surface Appearance of Woven Fabrics Made with Injected Slub Yarn in Weft

    Ray, Nemai Chandra; Mukhopadhyay, Arunangshu; Midha, Vinay Kumar


    Fancy yarn fabrics are susceptible to abrasive damage during washing and usage but the extent of damage varies with construction and type of fabric. In the present study, effect of different slub parameters viz. slub length, slub thickness and slub frequency of single base injected slub yarn on abrasive damage of woven fabrics has been studied when injected slub yarns are used in weft only. Abrasive damage has been assessed by two ways using loss in fabric mass and deterioration in fabric appearance due to abrasion. These two techniques provide entirely different effect of injected slub yarn parameters on abrasive damage of woven fabric. Fabric abrasion damage in terms of mass loss is not affected by slub thickness and damage is least when both slub length and slub frequency are at central/medium level. Under visual assessment it is observed that all the slub parameters have significant influence on abrasive damage of woven fabric. It is possible to have lower damage in surface appearance in spite of higher mass loss of fabric due to abrasion.

  12. NK cells are necessary for recovery of corneal CD11c+ dendritic cells after epithelial abrasion injury

    Mechanisms controlling CD11c(+) MHCII(+) DCs during corneal epithelial wound healing were investigated in a murine model of corneal abrasion. Selective depletion of NKp46(+) CD3- NK cells that normally migrate into the cornea after epithelial abrasion resulted in >85% reduction of the epithelial CD1...

  13. Study on jet type impact mill for concrete and design for abrasive jet system of pre-mixing type%喷射式混凝土冲磨机及其前混合式磨料喷射系统设计研究

    李浩平; 李峰; 张涛


    研究了混凝土抗冲刷磨损试验中的旋转喷射式试验原理,分析了磨料水射流工作原理及工作特点,并将前混合式磨料射流原理引入到水砂喷射系统中,研制了旋转喷射式混凝土抗冲耐磨试验机.本喷射系统特点:冲刷状况更接近混凝土真实工况,冲击力大,冲刷范围广,速度高,冲磨效果好,能够有效地对不同配合比混凝土的抗冲磨性能作出比较.%The principle of rotating-jet mode test for concrete under abrasion resistance test is studied in it as well as the working principle and characteristics of abrasive water jet is analyzed,then the principle of abrasive jet of pre-mixing type is introduced into the water sand jet system. Thus rotating-jet mode abrasion resistance testing machine for concrete has been developed which is characterized with erosion much closer to the real condition of concrete ,great impact,large erosion area,high speed,good erosion effect,and comparing on abrasion resistance performance can be effectively carried out for concrete with different proportion.

  14. Abrasive Wear Behaviors of Light-weight Austenitic Fe-24Mn-7Al-1C Steel and Mn13Cr2 Steel

    Shi-guang PENG; Ren-bo SONG; Zhi-dong TAN; Chang-hong CAI; Ke GUO; Zhong-hong WANG


    The impact abrasive wear behaviors of light-weight austenitic Fe-24Mn-7Al-1C steel with increasing impact wear conditions were studied by comparing with the modified Hadfield (Mn13Cr2)steel.Wear tests were performed with the MLD-10 abrasive wear testing machine.Main parameters such as impact energy,impacting frequency and wear time were evaluated.To explore the abrasive wear behaviors under different impact energies,the parameters in-cluding mass loss,wear resistance and hardness were evaluated in detail.The microstructures of the steels were fur-ther analyzed using optical microscopy (OM),scanning electron microscopy (SEM),transmission electron micros-copy (TEM)and X-ray diffraction (XRD).Results showed that the light-weight austenitic Fe-24Mn-7Al-1C steel had a better wear resistance than Mn13Cr2 steel under the impact energy tested.The wear resistance of light-weight austenitic Fe-24Mn-7Al-1C steel was about 1.09-1.17 times as high as that of Mn13Cr2 steel under low and medi-um impact energy (0.5-2.0 J)conditions,and 1.41 times under high impact energy (4.0 J)condition.In Mn13Cr2 steel,the evolution of dislocation substructure with increasing impact energy showed typical stacking fault,interac-tion of twins and dislocations,as well as mechanical twins.The high work-hardening rate in Fe-24Mn-7Al-1C steel was caused by Taylor lattice and high density of dislocation tangles.

  15. Abrasive wear based predictive maintenance for systems operating in sandy conditions

    Woldman, M.; Tinga, T.; Heide, E. van der; Masen, M.A.


    Machines operating in sandy environments are damaged by the abrasive action of sand particles that enter the machine and become entrapped between components and contacting surfaces. In the case of the military services the combination of a sandy environment and the wide range of tasks to be fulfille

  16. Toothbrush abrasion, simulated tongue friction and attrition of eroded bovine enamel in vitro

    Vieira, A.; Overweg, E.; Ruben, J. L.; Huysmans, M. C. D. N. J. M.


    Objectives: Enamel erosion results in the formation of a softened layer that is susceptible to disruption by mechanical factors such as brushing abrasion, tongue friction and attrition. The aim of this study was to investigate the individual contribution of those mechanical insults to the enamel los

  17. Tapered toothbrush filaments in relation to gingival abrasion, removal of plaque and treatment of gingivitis

    Versteeg, P.A.; Piscaer, M.; Rosema, N.A.M.; Timmerman, M.F.; van der Velden, U.; van der Weijden, G.A.


    Objectives: To compare a tapered filament toothbrush (TFTB) to a control toothbrush (ADA) in their potential to cause gingival abrasion and improve the gingival condition following a period of experimental gingivitis. Methods: Thirty-two subjects refrained from brushing mandibular teeth for 21 days.

  18. Platelet response to corneal abrasion is necessary for acute inflammation and efficient re-epithelialization

    Purpose: Adhesion molecules play a critical role in leukocyte emigration to wound sites, but differences are evident in different vascular beds. This study investigates the contributions of P-selectin to neutrophil emigration into the cornea following central epithelial abrasion. Methods: Re-epithel...

  19. NK cells modulate the inflammatory response to corneal epithelial abrasion and thereby support wound healing

    Natural killer cells are lymphocytes of the innate immune system that have crucial cytotoxic and regulatory roles in adaptive immunity and inflammation. Herein, we consider a role for these cells in corneal wound healing. After a 2-mm central epithelial abrasion of the mouse cornea, a subset of clas...

  20. A review on nozzle wear in abrasive water jet machining application

    Syazwani, H.; Mebrahitom, G.; Azmir, A.


    This paper discusses a review on nozzle wear in abrasive water jet machining application. Wear of the nozzle becomes a major problem since it may affect the water jet machining performance. Design, materials, and life of the nozzle give significance effect to the nozzle wear. There are various parameters that may influence the wear rate of the nozzle such as nozzle length, nozzle inlet angle, nozzle diameter, orifice diameter, abrasive flow rate and water pressure. The wear rate of the nozzle can be minimized by controlling these parameters. The mechanism of wear in the nozzle is similar to other traditional machining processes which uses a cutting tool. The high pressure of the water and hard abrasive particles may erode the nozzle wall. A new nozzle using a tungsten carbide-based material has been developed to reduce the wear rate and improve the nozzle life. Apart from that, prevention of the nozzle wear has been achieved using porous lubricated nozzle. This paper presents a comprehensive review about the wear of abrasive water jet nozzle.

  1. An in vitro evaluation of selective demineralised enamel removal using bio-active glass air abrasion.

    Banerjee, Avijit; Pabari, Hiten; Paolinelis, George; Thompson, Ian D; Watson, Timothy F


    Unnecessary over-preparation of carious enamel often occurs clinically during operative caries management. The working hypothesis to be investigated in this study is the potential for bio-active glass air abrasion to remove selectively only demineralised enamel in artificial enamel lesions when compared to equivalent alumina air abrasion, so potentially minimising cavity over-preparation. Bisected artificial, paired smooth surface enamel lesions on ethics-approved, extracted sound human molars were created and subsequently air abraded with 27 μm alumina (n = 19) and bio-active glass (n = 19). The difference between pre-operative lesion boundary and post-operative cavity margin was calculated following optical confocal fluorescent assessment of the lesion boundary. Data indicated mean% over-preparation (sound enamel removal) of 176% with alumina and 15.2% for bio-active glass (p = 0.005). Bio-active glass abrasion removed completely the demineralised enamel from artificial lesions with clinically insignificant over-preparation of sound tissue, indicating technique selectivity towards grossly demineralised enamel. Alumina air abrasion resulted in substantial enamel removal in both sound and demineralised tissues indicating the operator selectivity required to use the techniques effectively in clinical practice.


    Stephen Jackson


    Full Text Available Continuous process improvement and automation have proven to be powerful tools for the wood processing industries in order to obtain better final product quality and thus increase profits. Abrasive machining represents an important and relevant process in the manufacturing and processing of wood products, which also implies high cost of materials and labor; therefore, special attention to this process is necessary. The objective of this work was to evaluate and demonstrate a process control system for use in the abrasive machining of wood and wood-based products. A control system was created on LabView® to integrate the monitoring process and the actions required, depending on the abrasive machining process conditions. The system acquires information from the optical sensor to detect loading and activate the cleaning system. The system continuously monitors the condition of the abrasive belt (tool wear by using an acoustic emission sensor and alerts the operator of the status of the belt (green, yellow, and red lights indicating satisfactory, medium, and poor belt condition. The system also incorporates an additional safety device, which helps prevent permanent damage to the belt, equipment, or workpiece by alerting the operator when an excessive temperature has been reached. The process control system proved that automation permits enhancement in the consistency of the belt cleaning technique by the elimination of the human errors. Furthermore, this improvement also affects the cost by extending the life of the belt, which reduces setup time, belt cost, operation cost, as well as others.

  3. PAGMan - propelled abrasive grit to manage weeds in soybean and corn

    New tools for controlling weeds would be useful for soybean and corn production in organic systems or in systems in which weeds developed resistance to multiple herbicides. Here we report on two developments: (i) the safety to soybean seedlings of using air-propelled abrasive grit (PAG) for managing...

  4. Laser abrasion for cosmetic and medical treatment of facial actinic damage

    David, L.M.; Lask, G.P.; Glassberg, E.; Jacoby, R.; Abergel, R.P.


    Previous studies have shown the carbon dioxide (CO/sub 2/) laser to be effective in the treatment of actinic cheilitis. After CO/sub 2/ laser abrasion, normal skin and marked cosmetic improvement of the lip were noted. In our study, twenty-three patients were treated with CO/sub 2/ laser abrasions for cosmetic improvement of facial lines and actinic changes. Pre- and postoperative histopathologic examinations were made on two patients. Preoperative examination of specimens from actinically damaged skin showed atypical keratinocytes in the basal layer of the epidermis, with overlying dense compact orthokeratosis and parakeratosis. Abundant solar elastosis was seen in the papillary dermis. Postoperative histologic specimens showed a normal-appearing epidermis with fibrosis in the papillary dermis and minimal solar elastosis (about four weeks after laser treatment). At present, various modalities are available for the regeneration of the aged skin, including chemical peels and dermabrasion. Significantly fewer complications were noted with CO/sub 2/ laser abrasion than with these methods. Thus, CO/sub 2/ laser abrasion can be useful in the cosmetic and medical treatment of the aged skin. Marked clinical and histologic improvement has been demonstrated.

  5. Raman study of diamond-based abrasives, and possible artefacts in detecting UHP microdiamond

    Nasdala, Lutz; Steger, Simon; Reissner, Claudia


    Raman spectral characteristics of a range of diamond-based abrasives (powders and sprays) and drilling and cutting tools, originating from preparation laboratories worldwide, are presented. Some abrasives show strong broadening of the main diamond band [FWHM (full width at half band-maximum) > 5 cm- 1] accompanied by strong band-downshift (ν˜ = 1316-1330 cm- 1). Others are characterised by moderate band broadening (FWHM = 1.8-5 cm- 1) at rather regular band position (ν˜ = 1331-1333 cm- 1). In addition we found that a ;fresh; abrasive and its used analogue may in some cases show vast differences in their Raman spectra. The Raman parameters of diamond-based abrasives overlap widely with Raman parameters of UHP (ultra-high pressure) microdiamond. It is hence impossible to assign diamond detected in a geological specimen to either an introduced artefact or a genuine UHP relict, from the Raman spectrum alone. Raman is an excellent technique for the detection of minute amounts of diamond; however it does not provide conclusive evidence for the identification of UHP microdiamond. The latter requires thorough verification, for instance by optical microscopy or, if doubts cannot be dispelled, transmission electron microscopy.

  6. Study on Process of Preparing Fe-Al2O3 Magnetic Abrasive by High Energy Ball Milling%高能球磨法制备Al2O3/Fe磁性磨粒的工艺研究

    王晓峰; 李文辉


    Magnetic abrasive finishing machining technology is a new technology to use the magnetic field force produced by permanent magnetic or electromagnetic device asthe driving force of magnetic abrasive finishing machining of parts surface,which can realize the surface polishing,deburring,eliminating the micro crack,and reducing the surface roughness of parts.4 new technology of preparing magnetic abrasives used high energy ball milling was put forward and the working principle was analyzed in the ball milling.Pure iron powder was used as the magnetic phase,corundum powder as the abrasive,and three different times Fe-Al2O3 magnetic abrasives were prepared by high energy ball milling method.X-ray diffraction and SEM were used to analyze the morphology and phase components of the magnetic abrasives.Magnetic flux density of the magnetic abrasives were tested by the instrument.It finds that the process is easy and low cost,so it would have great hope to accomplish large-scale industrialized production.%磁性磨粒光整加工技术是利用永磁或者电磁发生装置产生的磁场力作为磁性磨粒的源动力对零件表面进行光整加工的一种新技术,它可以实现对零件进行表面抛光、去除毛刺、消除微观裂纹、降低表面粗糙度等加工.提出应用高能球磨法制备磁性磨粒的新工艺,分析了球磨过程中的工作原理.用纯铁粉作为磁性体,三氧化二铝粉作为磨料相,采用高能球磨法制备了三种不同时间的Fe-Al2O3磁性磨粒.采用X射线衍射仪和扫描电子显微镜分析了该磁性磨粒的物相组成和外观形貌,用特斯拉仪测试了磁性磨粒的磁感应强度.发现了该工艺简单,成本低,且有望进行大规模工业化生产.

  7. Structural transformations and wear resistance of abrasive-affected amorphous Fe- and Co-based alloys

    Korshunov, L. G.; Chernenko, N. L.


    The abrasive wear resistance of the Fe64Co30Si3B3, Fe82.6Nb5Cu3Si8B1.4, Co86.5Cr4Si7B2.5, and Fe81Si4B13C2 amorphous alloys (ribbon 30 μm thick) has been investigated upon sliding over fixed abrasives (corundum and silicon carbide). The character of fracture of the surface and structural transformations initiated in these materials by the abrasive action have been studied by the metallographic, X-ray diffraction, and electron-microscopic methods. It has been shown that the abrasive wear resistance of the amorphous alloys is smaller by a factor of 1.6-2.9 than that of the Kh12M and U8 tool steels possessing approximately the same level of hardness. A pronounced softening of the surface layer of the amorphous alloys in the process of wear, which is characterized by a decrease in their microhardness reaching 12.5%, has been found. It has been shown that in the surface layer of these amorphous alloys upon wear there arises a small amount (on the order of several volume percent) of the nanocrystalline structure, which does not exert a marked effect on the microhardness and wear resistance of the alloys. In the alloys under study, the main factor that is responsible for their comparatively low abrasive wear resistance is their local softening in the process of wear caused by specific features of deformation processes occurring heterogeneously under the action of high shear contact stresses.

  8. Patient preference: conventional rotary handpieces or air abrasion for cavity preparation.

    Malmström, Hans S; Chaves, Yvette; Moss, Mark E


    It has been suggested that patients should accept the use of the air abrasion technique over the conventional handpiece due to the reduced need for anesthesia. Technologies for both air abrasion and the conventional rotary handpiece have, in recent decades, seen major improvements, but there are no recent scientific publications that evaluate the patient's preference for these two technologies when performing a cavity preparation. This study determined the patient's preference for air abrasion or the rotary handpiece for removing occlusal fissure carious lesions in mandibular premolars. Ten healthy subjects 18 years of age or older were recruited from the General Dentistry Clinic of the University of Rochester Eastman Dental Center, with fissure caries at a DEJ depth of similar size (determined by radiographs and clinical examination) in any two mandibular premolars in opposite quadrants. Within each subject, the two methods of caries removal were randomly assigned. In one premolar, air abrasion was used for cavity preparation, and in the other premolar, a conventional rotary handpiece was used. At each visit prior to treatment, the patients were instructed to complete the Emotional Status (ES) questionnaire (SUNY University at Buffalo Craniofacial Pain Clinic) to assess differences in their emotional status between appointments. At each appointment, when the restorative treatment was completed, patients were instructed to rate their pain on the Visual Analogue Scale (VAS). A technique preference questionnaire was given after the second appointment. The subjects rated the perception of pain as significantly lower (p cavity preparation when removing fissural caries in mandibular premolars and most subjects did not experience any pain when air abrasion was used.

  9. Influence of air-abrasion executed with polyacrylic acid-Bioglass 45S5 on the bonding performance of a resin-modified glass ionomer cement.

    Sauro, Salvatore; Watson, Timothy F; Thompson, Ian; Toledano, Manuel; Nucci, Cesare; Banerjee, Avijit


    The aim of this study was to test the microtensile bond strength (μTBS), after 6 months of storage in PBS, of a resin-modified glass ionomer cement (RMGIC) bonded to dentine pretreated with Bioglass 45S5 (BAG) using various etching and air-abrasion techniques. The RMGIC (GC Fuji II LC) was applied onto differently treated dentine surfaces followed by light curing for 30 s. The specimens were cut into matchsticks with cross-sectional areas of 0.9 mm(2). The μTBS of the specimens was measured after 24 h or 6 months of storage in PBS and the results were statistically analysed using two-way anova and the Student-Newman-Keuls test (α = 0.05). Further RMCGIC-bonded dentine specimens were used for interfacial characterization, micropermeability, and nanoleakage analyses by confocal microscopy. The RMGIC-dentine interface layer showed no water absorption after 6 months of storage in PBS except for the interdiffusion layer of the silicon carbide (SiC)-abraded/polyacrylic acid (PAA)-etched bonded dentine. The RMGIC applied onto dentine air-abraded with BAG/H(2)O only or with BAG/PAA-fluid followed by etching procedures (10% PAA gel) showed no statistically significant reduction in μTBS after 6 months of storage in PBS. The abrasion procedures performed using BAG in combination with PAA might be a suitable strategy to enhance the bonding durability and the healing ability of RMGIC bonded to dentine.

  10. Improvement of Surface Roughness Quality for Stainless Steel 420 Plate Using Magnetic Abrasive Finishing Method

    Yahya M. Hamad


    Full Text Available An experimental study was carried out to improve the surface roughness quality of the stainless steel 420 using magnetic abrasive finishing method (MAF. Four independent operation parameters were studied (working gap, coil current, feed rate, and table stroke, and their effects on the MAF process were introduced. A rotating coil electromagnet was designed and implemented to use with plane surfaces. The magnetic abrasive powder used was formed from 33%Fe and 67% Quartz of (250µm mesh size. The lubricant type SAE 20W was used as a binder for the powder contents. Taguchi method was used for designing the experiments and the optimal values of the selected parameters were found. An empirical equation representing the relation between surface roughness with operation parameters have been achieved.

  11. Study on NDT Fault Diagnosis of the Ball Bearing under Stage of Abrasion by Infrared Thermography

    Seo, Jin Ju; Hong, Dong Pyo [Chonbuk National University, Jeonju (Korea, Republic of); Kim, Won Tae [Kongju National University, Gongju (Korea, Republic of)


    For fault detection about the abrasion stage of rotational machineries under the dynamic loading conditions unlike the traditional diagnosis method used in the past decade, the infrared thermographic method with its distinctive advantages in non-contact, non-destructive, and visible aspects is proposed. In this paper, by applying a rotating deep-grooved ball bearing, passive thermographic experiments were conducted as an alternative way to proceeding the traditional fault monitoring on spectrum analyzer. As results, the thermographic experiment was compared with the traditional vibration spectrum analysis to evaluate the efficiency of the proposed method. Based on the results obtained as NDT, the temperature characteristics and abnormal fault detections of the ball bearing according to the abrasion stage were analyzed.

  12. Structure and Abrasive Wear of Composite HSS M2/WC Coating

    S. F. Gnyusov


    Full Text Available Features of phase-structure formation and abrasive wear resistance of composite coatings “WC-M2 steel” worn against tungsten monocarbide have been investigated. It was established that adding 20 wt.% WC to the deposited powder mixture leads to the increase in M6C carbide content. These carbides show a multimodal size distribution consisting of ~5.9 μm eutectic carbides along the grain boundaries, ~0.25 μm carbides dispersed inside the grains. Also a greater amount of metastable austenite (~88 vol.% is found. The high abrasive wear resistance of these coatings is provided by γ→α′-martensitic transformation and multimodal size distribution of reinforcing particles.

  13. Structure and abrasive wear resistance of R6M5 steel-tungsten carbide composite coatings

    Gnyusov, S. F.


    Features of the structure formation, composition, and abrasive wear resistance of R6M5 steel-tungsten carbide (R6M5-WC) composite coatings have been studied as dependent on the WC content. The introduction of ˜20 wt % WC into the hardening composition leads to an increase in the fraction of M6C carbide (in the form of eutectic inclusions with average size ˜5.9 μm at grain boundaries and dispersed ˜0.25 μm particles in the volume of grains), while a large proportion of metastable austenite (˜88 vol %) is still retained. The R6M5-WC coatings exhibit high abrasive wear resistance, which is ensured by the γ → α' martensite transformation during friction and a muiltimodal size distribution of hardening particles.

  14. Abrasive wear behaviour of bio-active glass ceramics containing apatite

    I Sevim; M K Kulekci


    In this study, abrasive wear behaviour of bio-active glass ceramic materials produced with two different processes is studied. Hot pressing process and conventional casting and controlled crystallization process were used to produce bio-active ceramics. Fracture toughness of studied material was calculated by fracture toughness equations using experimental hardness results of the bio-active glass ceramic material. Two fracture toughness equations in the literature were used to identify the wear behaviour of studied ceramics. Wear resistance results that identified with both of the equations were similar. The results showed that the abrasive wear resistance of the bio-active glass ceramics produced with hot pressing process was found to be higher than that of the ceramics produced by conventional casting and controlled crystallization process.

  15. A study on practical use of underwater abrasive water jet cutting

    Yamaguchi, Hitoshi; Demura, Kenji


    The practicality of underwater abrasive water jet cutting technology was studied in experiments. A study of abrasives in slurried form showed that optimum polymer concentration can be selected to suit underwater conditions. For the long-distance transport of slurry from the ocean surface to the ocean floor, a direct supply system by hose proved to be practical. This system takes advantage of the insolubility of the slurry in water due to a difference in specific gravity. For cutting thick steel plate at great ocean depths, a simulation with a pressurized container revealed the requirements for actual cutting. Confirmation of remote cutting operations will become the most important technology in field applications. Underwater sound vibration characteristics were found to change significantly in direct response to modifications in cutting conditions. This will be important basic data to develop an effective sensoring method.

  16. Kerf modelling in abrasive waterjet milling using evolutionary computation and ANOVA techniques

    Alberdi, A.; Rivero, A.; Carrascal, A.; Lamikiz, A.


    Many researchers demonstrated the capability of Abrasive Waterjet (AWJ) technology for precision milling operations. However, the concurrence of several input parameters along with the stochastic nature of this technology leads to a complex process control, which requires a work focused in process modelling. This research work introduces a model to predict the kerf shape in AWJ slot milling in Aluminium 7075-T651 in terms of four important process parameters: the pressure, the abrasive flow rate, the stand-off distance and the traverse feed rate. A hybrid evolutionary approach was employed for kerf shape modelling. This technique allowed characterizing the profile through two parameters: the maximum cutting depth and the full width at half maximum. On the other hand, based on ANOVA and regression techniques, these two parameters were also modelled as a function of process parameters. Combination of both models resulted in an adequate strategy to predict the kerf shape for different machining conditions.

  17. The effectiveness of the air-powder abrasive device on the tooth and periodontium: an overview.

    Kozlovsky, A; Soldinger, M; Sperling, I


    The characteristics of the air-powder abrasive device (APAD) was reviewed from the current dental literature and found to be an excellent alternative to traditional methods for stain and plaque removal. Access to crowded teeth, grooves and involved furcation areas are easily obtainable with less operator fatigue. The APAD slurry produces different root surface abrasiveness, depending on the method of use. Extended maintenance periods of exposed root surface using the APAD can result in an enormous loss of root structure. To avoid permanent damage of the root, the device should be used with overlapping strokes and root exposure to the APAD slurry should be minimized. The device can be used for total cementum removal with less operator fatigue and more reproducibility than with hand instruments, leaving smooth and clean surfaces. In addition, the device may be a valuable tool in the detoxification of root surfaces during periodontal surgery.

  18. Examining of abrasion resistance of hybrid composites reinforced with SiC and Cgr particles

    M. Łągiewka


    Full Text Available The presented work discusses the influence of the type and volume percentage of particulate reinforcement consisting of mixed silicon carbide and graphite on the abrasion wear of hybrid composites with AlMg10 matrix. Also the macro photos of frictional surfaces have been shown and the results of hardness measurements have been presented. The performed examinations have allowed for stating that the mixture of SiC and Cgr particles changes in favour the tribological properties of the matrix alloy. It has been also proved that introducing hard reinforcing particles along with soft lubricating ones allows for achieving the material exhibiting high abrasion resistance, and moreover, the graphite particles protect the abraded surface from the destructive action of silicon carbide particles. Also hardness measurements have been performed and the resulting conclusion is that the composite hardness increases with an increase in volume fraction of the reinforcing particles.

  19. Influence of scale-up on the abrasion of tablets in a pan coater.

    Mueller, Ronny; Kleinebudde, Peter


    The purpose of this study was to examine the influence of batch size during scale-up on the abrasion and edge splitting of flat faced lactose tablets. The weight loss of white tracer tablets in a batch of blue coated tablets was investigated in a laboratory scale pan coater and a pilot scale pan coater as a function of different pan speeds and mixing times. It was observed that increasing batch size resulted in a decreased weight loss due to less edge damaging. The higher number of tablet impacts at the pan wall in the laboratory scale compared to the pilot scale might be the reason for this phenomenon. The common assertion that an increase in batch size in scale-up leads to a higher abrasion or tablet damaging was not supported in the current study.

  20. Utilizing a Magnetic Abrasive Finishing Technique (MAF Via Adaptive Nero Fuzzy(ANFIS

    Amer A. Moosa


    Full Text Available An experimental study was conducted for measuring the quality of surface finishing roughness using magnetic abrasive finishing technique (MAF on brass plate which is very difficult to be polish by a conventional machining process where the cost is high and much more susceptible to surface damage as compared to other materials. Four operation parameters were studied, the gap between the work piece and the electromagnetic inductor, the current that generate the flux, the rotational Spindale speed and amount of abrasive powder size considering constant linear feed movement between machine head and workpiece. Adaptive Neuro fuzzy inference system (ANFIS was implemented for evaluation of a series of experiments and a verification with respect to specimen roughness change has been optimized and usefully achieved by obtained results were an average of the error between the surface roughness predicted by model simulation and that of direct measure is 2.0222 %.


    Mehdi Shiva; Hossein Atashi; Mahtab Hassanpourfard


    In this study,an application of artificial neural network (ANN) has been presented in modeling and studying the effect of compounding variables on abrasion behavior of rubber formulations.Three case studies were carried out in which the experiment data were collected according to classical response surface designs.Besides developing the ANN models,we developed response surface methodology (RSM) to confirm the ANN predictions.A simple relation was employed for determination of relative importance of each variable according to ANN models.It was shown through these case studies that ANN models delivered very good data fitting and their simulating curves could help the researchers to better understand the abrasion behavior.

  2. Research on Abrasion Simulation of DeNOx Honeycomb Catalysts in Flue Gas%蜂窝式脱硝催化剂在烟气中磨损行为的模拟研究

    肖雨亭; 徐莉; 贾曼; 汪德志; 彭光军


    The abrasion performance tests for different types of honeycomb DeNO, catalysts used for SCR denitrification under different conditions are carried out with a simulation testing device. The tests show that the inner wall abrasion of the catalysts is the main reason for the reduction of abrasion resistance, which coincides with "Magnus Effect" theory. The result also indicates that the abrasion degree of lower-layer catalysts is more serious than that of upper-layer catalysts when multi-layer catalyst arrangement is adopted. In high fly ash operating conditions, the type selection of catalyst should be made scientifically and discreetly. When the dust concentration exceeds 30 g/ m3, the standard type of the catalyst with the thickness of more than 1.0 mm is recommended.%利用耐磨损性能模拟试验装置,在不同条件下对用于选择性催化还原法(SCR)脱硝的多种规格的蜂窝式脱硝催化剂进行了耐磨损性能的试验研究.结果表明,壁面磨损是导致蜂窝式催化剂耐磨损性能下降的主要原因,其磨损行为符合“马格努斯”效应的理论;采用多层布置的催化剂中,下层催化剂的磨损要比上层相对严重;在高浓度飞灰工况中,要科学慎重地进行催化剂选型,当飞灰质量浓度超过30 g/m3时,建议选用标准型、壁厚大于1.0 mm的催化剂.

  3. Relations of abrasion resistance and hardness of 16Cr-3C white irons with retained austenite content

    Zhiping Sun; Rulin Zuo; Cong Li; Baoluo Shen; Shengji Gao; Sijiu Huang


    The relationship between the retained austenite content of the matrix in 16Cr-3C white irons and the abrasion resistance was investigated. The results show that: (1) the abrasion resistance can be improved by sub-critical heat treatment, which could be attributed to the decrease of the retained austenite content; (2) both the abrasion resistance and hardness can be improved by controlling the retained austenite content below 20%-30% and arrive at the maximum when the retained austenite content is reduced to about 10%; (3) the abrasion resistance decreases abruptly once the retained austenite content is lower than 10%, which stems from both the in situ transformation of (Fe, Cr)23C6 to M3C carbides and the formation of pearlitic matrix.

  4. Treatment of gingival hyperpigmentation with rotary abrasive, scalpel, and laser techniques: A case series

    Murthy, M Bhanu; Kaur, Jasjit; Das, Rupali


    Melanin pigmentation often occurs in the gingiva as a result of an abnormal deposition of melanin, due to which the gums may appear black, but the principles, techniques, and management of the problems associated with gingival melanin pigmentation are still not fully established. Depigmentation procedures such as scalpel surgery, gingivectomy with free gingival autografting, electrosurgery, cryosurgery, chemical agents such as 90% phenol and 95% alcohol, abrasion with diamond bur, Nd: YAG las...

  5. Experimental Investigations into Abrasive Waterjet Machining of Carbon Fiber Reinforced Plastic

    Prasad D. Unde


    Full Text Available Abrasive waterjet machining (AWJM is an emerging machining process in which the material removal takes place due to abrasion. A stream of abrasive particles mixed with filtered water is subjected to the work surface with high velocity. The present study is focused on the experimental research and evaluation of the abrasive waterjet machining process in order to evaluate the technological factors affecting the machining quality of CFRP laminate using response surface methodology. The standoff distance, feed rate, and jet pressure were found to affect kerf taper, delamination, material removal rate, and surface roughness. The material related parameter, orientation of fiber, has been also found to affect the machining performance. The kerf taper was found to be 0.029 for 45° fiber orientation whereas it was 0.036 and 0.038 for 60° and 90°, respectively. The material removal rate is 18.95 mm3/sec for 45° fiber orientation compared to 18.26 mm3/sec for 60° and 17.4 mm3/sec for 90° fiber orientation. The Ra value for 45° fiber orientation is 4.911 µm and for 60° and 90° fiber orientation it is 4.927 µm and 4.974 µm, respectively. Delamination factor is found to be more for 45° fiber orientation, that is, 2.238, but for 60° and 90° it is 2.029 and 2.196, respectively.

  6. Investigation of sandwich material surface created by abrasive water jet (AWJ via vibration emission

    P. Hreha


    Full Text Available The paper presents research a of abrasive waterjet cutting of heterogeneous “sandwich“ material with different Young modulus of elasticity of the cutted surface geometry by means of vibration emission. In order to confirm hypothetical assumptions about direct relation between vibration emission and surface quality an experiment in heterogeneous material consisting of stainless steel (DIN 1.4006 / AISI 410 and alloy AlCuMg2 has been provided.

  7. High abrasion resistance coating materials from organic/inorganic hybrid materials produced by the sol-gel method


    A series of new high abrasion resistance coating materials have been prepared utilizing organic/inorganic hybrid materials formed by cohydrolyzing a metal alkoxide sol (e.g. silicon, aluminum, titanium, or zirconium metal alkoxide sol) with one or more bis(trialkoxysilane-containing) organic components or related functionalized species. These hybrid materials show optical clarity and improve the abrasion resistance of polymer substrates when applied as coatings and cured on such substrates.

  8. An investigation on surface roughness of granite machined by abrasive waterjet

    Gokhan Aydin; Izzet Karakurt; Kerim Aydiner


    Abrasive waterjet (AWJ) cutting is an emerging technology which enables the shaping of practically all engineering materials. However, AWJ cutting may cause roughness and waviness on the cut surface. This significantly affects the dimensional accuracy of the machined part and the quality of surface finish. In this study, the surface roughness of three granites is experimentally investigated for varying process parameters in abrasive waterjet. The philosophy of the Taguchi design is followed in the experimental study. Effects of the control (process) factors on the surface roughness are presented in terms of the mean of means responses. Additionally, the data obtained are evaluated statistically using the analysis of variance (ANOVA) to determine significant process parameters affecting the surface roughness. Furthermore, effects of the material properties on the surface roughness are assessed. It was statistically found that the water pressure and the abrasive flow rate are the most significant factors influencing the surface roughness of granites. Additionally, a consistent relationship between the material grain size and surface roughness of the granites was observed.

  9. Ergonomics of abrasive blasting: a comparison of high pressure water and steel shot.

    Rosenberg, Beth; Yuan, Lu; Fulmer, Scott


    Abrasive blasting with silica sand has long been associated with silicosis. Alternatives to sand are being used increasingly. While NIOSH has done extensive investigations of the respiratory effects of the substitutes for sand, the ergonomic effects of the substitutes have not been examined. Too often, hazards are shifted, and technologies that might save workers' lungs could do so at the expense of their musculoskeletal systems. Hence, the objective of this study was to examine the ergonomic effects of alternatives to sand. Multiple methods, both qualitative and quantitative, were used to yield numerous kinds of data for the analysis of exposures to abrasive blasters. PATH, a method for quantifying ergonomic exposure in non-routine work, was combined with interviews with workers, biomechanical modeling and noise level readings to assess the ergonomics of two abrasive blasting operations: high-pressure water and steel shot. Advantages and disadvantages of each medium are discussed. High-pressure water was slightly less ergonomically stressful, environmentally cleaner, much quieter and less dusty that steel shot, and it was reported to be slower on those tasks where both media could be used.

  10. Effect of abrasive surface roughening on the secondary yield of various metals

    Graves, Timothy


    The secondary electron yield of metallic conductors plays a critical role in the development of multipactor discharges. These discharges require a secondary yield greater than unity at the appropriate energy level for sustained breakdown. By reducing the secondary yield below unity in the necessary energy range, multipactor and multipactor-induced glow discharges can be eliminated. Surface roughening has been shown to successfully lower the secondary yield to below unity (ref. 1). In addition, abrasive bead blasting has been shown to effectively reduce the secondary yield of copper surfaces while preserving voltage breakdown characteristics (ref. 2). This study investigates the effect of abrasive surface roughening on the secondary yield of materials such as copper, aluminum, and stainless steel. In addition to measuring the change in the secondary yield as a function of abrasive particle size, the multipactor resistance and voltage breakdown characteristics are investigated. In addition, the effect of vacuum conditioning via multipactor and rf plasma cleaning on the roughened surfaces will be discussed. Ref. 1. H. Bruining. Physics and Applications of Secondary Electron Emission. McGraw-Hill, NY, 1954. Ref. 2. T. P. Graves, Ph.D. Thesis, MIT. 2007

  11. Experimental Study on Layered Ice Bonded Abrasive Polishing of Glass-ceramics

    Yuli SUN


    Full Text Available Layered ice bonded abrasive tools (LIBAT is a new kind of one which not only has the ability of lapping and polishing but also has the effect of self-dressing. In this paper, two kinds of layered ice bonded abrasive tools were designed and manufactured. Experimental studies on layered ice bonded abrasive (LIBA polishing of glass-ceramics were conducted. The results show that the surface topography of glass-ceramics polished by micro α-Al2O3-nano α-Al2O3 LIBAT is better than that of polished by micro α-Al2O3-nano SiO2 LIBAT. The surface roughness Sa of glass-ceramics polished by the two kinds of LIBAT is at the nanometer scale. The reasons of this phenomenon were analyzed. The experimental results illustrate that the LIBAT shows good effect and can be used in production practice. DOI:

  12. The surface quality of AWJ cut parts as a function of abrasive material reusing rate

    Schnakovszky, C.; Herghelegiu, E.; Radu, M. C.; Tampu, N. C.


    Abrasive water jet cutting (AWJ) has been extensively used during the last years to process a large variety of materials since it offers important advantages as a good quality of the processed surface, without heat affected zones, low environmental impact (no emission of dust or other compounds that endanger the health of the user), small induced mechanical stresses etc. The main disadvantage is the high cost of processing (cost of equipment and consumables). In view of this, the effects of reusing the abrasive material on the quality of processed surface are investigated in this paper. Two steel materials were used: OL 37 (S 235) with large applicability in machine building industry and 2P armor steel used in the arms industry. The reusing rate of the garnet abrasive material was: 0%, 20%, 40%, 60%, 80% and 100%. The quality of processed surface was quantified by the following parameters: width at the jet inlet (Li), width at the jet outlet (Lo), inclination angle (α), deviation from perpendicularity (u) and roughness (Ra).

  13. Rapid manufacturing of SiC molds with micro-sized holes using abrasive water jet

    Bo-Sung SHIN; Kang-Su PARK; Yeon-Kyoung BAHK; Sun-Ki PARK; Jung-Han LEE; Jeung-Sang GO; Myung-Chang KANG; Chae-Moon LEE


    Silicon carbide (SIC) is highly wear resistant with good mechanical properties, including high temperature strength, excellent chemical resistance, and high thermal conductivity and thermal shock resistance. SiC molds, which can be produced with diverse microstructural features, are now widely used in glass molding owing to their excellent characteristics, and also have potential applicability in IT industries. SiC molds are traditionally fabricated by silicon micromachining or dicing. The fabrication cost of silicon micromachining is very high, however, because several expensive masks are needed. Furthermore, the fabrication time is very long. Meanwhile, it is difficult to make micro-patterned molds with arbitrary shapes using dicing saws. Abrasive water jet (AWJ) is widely applied to cut and drill very brittle, soft and fibrous materials. It offers high energy density, the absence of a heat affected zone(HAZ), high performance, and an environment friendly process. In spite of these advantages, micro-hole drilling via conventional AWJ processing suffers from notable shortcomings. We proposed a new abrasive supplying method of AWJ. The proposed method reduces frosting phenomena, and provides micro-machining of AWJ. The characteristics of a hole machined was investigated by the proposed AWJ process according to the ratio of water and abrasives. With the optimal experimental conditions, 3 × 3 array SiC molds with the diameter of 700 μm and depth of 900 μm were successfully manufactured.

  14. Improved Soft Abrasive Flow Finishing Method Based on Turbulent Kinetic Energy Enhancing

    LI, Jun; JI, Shiming; TAN, Dapeng


    Soft abrasive flow(SAF) finishing can process the irregular geometric surfaces, but with the matter of low processing efficiency. To address the issue, an improved SAF finishing method based on turbulent kinetic energy enhancing is proposed. A constrained flow passage with serration cross-section is constructed to increase the turbulence intensity. Taking the constrained flow passage as the objective, a two-phase fluid dynamic model is set up by using particle trajectory model and standard k-ɛ turbulence model, and the flow field characteristics of the flow passage are acquired. The numerical results show that the serration flow passage can enhance the turbulence intensity, uniform the particles distribution, and increase the particle concentration near the bottom wall. The observation results by particle image velocimetry(PIV) show that the internal vortex structures are formed in flow passage, and the abrasive flow takes on turbulence concentrating phenomenon in near-wall region. The finishing experiments prove that the proposed method can obtain better surface uniformity, and the processing efficiency can be improved more 35%. This research provides an abrasive flow modeling method to reveal the particle motion regulars, and can offer references to the technical optimization of fluid-based precision processing.

  15. Adhesive interfaces of enamel and dentin prepared by air-abrasion at different distances

    Chinelatti, Michelle Alexandra [School of Dentistry of Ribeirao Preto/University of Sao Paulo, Department of Restorative Dentistry, Ribeirao Preto-SP (Brazil)]. E-mail:; Andreolli do Amaral, Thais Helena [School of Dentistry of Ribeirao Preto/University of Sao Paulo, Department of Restorative Dentistry, Ribeirao Preto-SP (Brazil); Borsatto, Maria Cristina [School of Dentistry of Ribeirao Preto/University of Sao Paulo, Department of Pediatric Dentistry, Ribeirao Preto-SP (Brazil); Palma-Dibb, Regina Guenka [School of Dentistry of Ribeirao Preto/University of Sao Paulo, Department of Restorative Dentistry, Ribeirao Preto-SP (Brazil); Corona, Silmara Aparecida Milori [School of Dentistry of Ribeirao Preto/University of Sao Paulo, Department of Restorative Dentistry, Ribeirao Preto-SP (Brazil)


    The purpose of this study was to analyse, by scanning electron microscopy (SEM), the morphology of enamel and dentin/adhesive interfaces in cavities prepared by air-abrasion at different working distances. Thirty sound third human molars were selected and, on both their buccal and lingual surfaces, class V cavities were prepared by air-abrasion, at 2-, 4-, 6-, 8- and 10-mm working distances, or high-speed bur (control group). After preparation, all cavities were etched with 35% phosphoric acid gel and restored with Single Bond/Filtek Z-250. Buccal and lingual surfaces were separated and restorations sectioned in a buccolingual direction, providing two sections of each cavity, which were analysed by scanning electron microscopy. It was observed that the distances of 6 and 8 mm promoted more homogeneous dentin/adhesive interfaces, with tags formation, and more uniform for enamel, which were similar to the control group. It may be concluded that the air-abrasion working distance can influence the morphology of enamel and dentin/adhesive interfaces, and the intermediate distances provided better adhesive interfaces.

  16. Evaluation of the effects of enameloplasty and air abrasion on sealant micro-leakage.

    Aliasghar Soleymani


    Full Text Available Micro-leakage, one of the major reasons for recurrent decays, may lead to uncontrollable flow of liquids, pulp inflammation and peri-apical pathology. The purpose of this in vitro study was to evaluate micro-leakage of pit and fissure sealants after using three different pit and fissure preparation techniques: 1 acid etching, 2 fissure enameloplasty and acid etching, and 3 air abrasion and acid etching.Sixty-nine extracted sound molars and premolars were randomly divided into three groups (23 samples in each group. Teeth were prepared using one of three occlusal surface treatments. Then the sealant was applied on the occlusal fissures of all teeth. The teeth were thermocycled and stored in normal saline. All teeth were sealed apically and coated with nail varnish and then were immersed in a 2% solution of methylen blue. Two buccolingual sections were made. The surfaces were scored 0 to 3 for the extent of micro-leakage using a stereomicroscope. Data were analyzed by Kruskal- wallis and Dunn procedure.Enameloplasty and acid etching were significantly different regarding micro-leakage (P= 0.016, but no significant difference in micro-leakage was observed between air abrasion and the other methods.Enameloplasty followed by acid etching produced significantly less micro-leakage than the acid etching technique. Air abrasion acid etching was better than the acid etching technique in reducing micro-leakage too.

  17. Erosion and abrasion on dental structures undergoing at-home bleaching

    Tarquinio SBC


    Full Text Available Flávio Fernando Demarco1, Sônia Saeger Meireles2, Hugo Ramalho Sarmento1, Raquel Venâncio Fernandes Dantas1, Tatiana Botero3, Sandra Beatriz Chaves Tarquinio11Graduate Program in Dentistry, School of Dentistry, Federal University of Pelotas, Brazil; 2Department of Operative Dentistry, Federal University of Paraíba, Brazil; 3Cariology, Restorative Science, and Endodontics Department, School of Dentistry, University of Michigan, MI, USAAbstract: This review investigates erosion and abrasion in dental structures undergoing at-home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled.Keywords: peroxide, tooth bleaching, enamel, dentin, erosion, abrasion

  18. Modeling of Tool Wear in Vibration Assisted Nano Impact-Machining by Loose Abrasives

    Sagil James


    Full Text Available Vibration assisted nano impact-machining by loose abrasives (VANILA is a novel nanomachining process that combines the principles of vibration assisted abrasive machining and tip-based nanomachining, to perform target specific nanoabrasive machining of hard and brittle materials. An atomic force microscope (AFM is used as a platform in this process wherein nanoabrasives, injected in slurry between the workpiece and the vibrating AFM probe which is the tool, impact the workpiece and cause nanoscale material removal. The VANILA process are conducted such that the tool tip does not directly contact the workpiece. The level of precision and quality of the machined features in a nanomachining process is contingent on the tool wear which is inevitable. Initial experimental studies have demonstrated reduced tool wear in the VANILA process as compared to indentation process in which the tool directly contacts the workpiece surface. In this study, the tool wear rate during the VANILA process is analytically modeled considering impacts of abrasive grains on the tool tip surface. Experiments are conducted using several tools in order to validate the predictions of the theoretical model. It is seen that the model is capable of accurately predicting the tool wear rate within 10% deviation.


    Kozachenko A. D.


    Full Text Available Brazes with increased viscosity are needed for brazing of abrasive diamond tools with working surface of complex contoured shape. It’s known that high viscosity is a property of composite brazes consisting of fusible matrix and refractory filler that is not melting during brazing. Goal of the work is to research the influence of refractory fillers on the process of composite brazing of diamond-abrasive tools and on that basis discover the optimal composition of braze. Composite brazes Sn-Cu-Co were researched in the work. It is determined that at least 26-28% (by mass of cobalt powder should be included in brazes for giving the braze Sn-Cu-Co necessary viscosity and for creation of uniform diamond-comprising layers with thickness up to 2.5 mm on the vertical layers and sharp edges of tools. It is determined that solid-state sintering of powders on the initial stage of heating the composite braze leads to emerging of internal stresses and forming cracks. Inert additions that prevent solid-state sintering should be include in braze to prevent cracking. Optimal inert addition for brazes Sn-Cu-Co is the tungsten powder. Minimum content of tungsten needed to prevent cracking is 6% (by mass. Optimal content of components in composition braze for brazing shaped diamond-abrasive tools is (% by mass: 30 Co, 20 Sn, 43 Cu, 7 W

  20. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    Milly, Hussam; Andiappan, Manoharan; Thompson, Ian; Banerjee, Avijit


    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  1. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    Milly, Hussam [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Andiappan, Manoharan [Unit of Dental Public Health, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Thompson, Ian [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Banerjee, Avijit, E-mail: [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Unit of Conservative Dentistry, King' s College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom)


    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p < 0.001) and the effect of altering the unit's operating parameters was significant (p < 0.001). In conclusion, BAG powder is more efficient than alumina in the selective removal of resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  2. Effect of using nano and micro airborne abrasive particles on bond strength of implant abutment to prosthesis.

    Rismanchian, Mansour; Davoudi, Amin; Shadmehr, Elham


    Connecting prostheses to the implant abutments has become a concern and achieving a satisfactory retention has been focused in cement-retention prostheses recently. Sandblasting is a method to make a roughened surface for providing more retention. The aim of this study was to compare effects of nano and micro airborne abrasive particles (ABAP) in roughening surface of implant abutments and further retention of cemented copings. Thirty Xive abutments and analogues (4.5 D GH1) were mounted vertically in self-cured acrylic blocks. Full metal Ni-Cr copings with a loop on the top were fabricated with appropriate marginal adaptation for each abutment. All samples were divided into 3 groups: first group (MPS) was sandblasted with 50 µm Al2O3 micro ABAP, second group (NSP) was sandblasted with 80 nm Al2O3 nano ABAP, and the third group (C) was assumed as control. The samples were cemented with provisional cement (Temp Bond) and tensile bond strength of cemented copings was evaluated by a universal testing machine after thermic cycling. The t test for independent samples was used for statistical analysis by SPSS software (version 15) at the significant level of 0.05. Final result showed significant difference among all groups (pABAP is an efficient way for increasing bond strengths significantly, but it seems that micro ABAP was more effective.

  3. Laboratory tests to assess optimal agricultural residue traits for an abrasive weed control system

    One of the biggest challenges to organic agricultural production and herbicide resistant crops in industrialized countries today is the non-chemical control of weed plants. Studies of new tools and methods for weed control have been motivated by an increased consumer demand for organic produce and c...

  4. Generation of Graphite Particles by Abrasion and Their Characterization

    Troy, Raymond Steven

    Self-efficacy beliefs that relate to teachers' motivation and performance have been an important area of concern for preservice teacher education. This study used a mixed-methods approach to investigate the changes in preservice elementary teachers' science self-efficacy beliefs and the factors associated in a specialized elementary physics content course. In addition, the study is one of few to investigate the relationship between the changes in science self-efficacy beliefs and changes in physical science conceptual understanding. Participants included fifty-one preservice elementary teachers enrolled in two term of the physical science content course. Data collection and analysis procedures included both qualitative and quantitative measures. Data collection included implementation of Science Teaching Efficacy Belief Instrument-B (STEBI-B) (Bleicher, 2004) and Physical Science Concept Test as pre- and post-test, two semi-structured interviews with 18 participants (nine each semester), classroom observations and artifacts. A pre-post, repeated measures multivariate analysis of variance (MANOVA) design was used to test the significance of differences between the pre- and post-surveys across time. Results indicated statistically significant gains in participants' science self-efficacy beliefs on both scales of STEBI-B - personal science teaching beliefs and outcome expectancy beliefs. Additionally, a positive moderate relationship between science conceptual understandings and personal science teaching efficacy beliefs was found. Post-hoc analysis of the STEBI-B data was used to select 18 participants for interviews. The participants belonged to each group representing the low, medium and high initial levels of self-efficacy beliefs. Participants' responses indicated positive shifts in their science teacher self-image and confidence to teach science in future. Four categories that represented the course-related factors contributing towards science self

  5. Assessment of the Abrasivity of Chinese Toothpastes%四种中国产牙膏磨损性的评价

    ParryJ; 赵守亮; 等


    目的:观察4种中国产牙膏对人牙本质的磨损性.方法:将新鲜拔除的人健康恒牙包埋于环氧树脂块中,表面磨平.开一牙本质窗并在刷牙机上刷1?@000次,以Talysurf 2表面测量仪测量牙本质磨损程度.结果:多数中国产牙膏具有较高的磨损性.结论:长期使用有潜在的导致牙齿磨损的可能性.%AIM:To investigate the dentine abrasivity of four commonly used Chinese dentifrices.METHODS:The freshly extracted sound human teeth were embedded in blocks of epoxy resin,then which were ground flat on a grinding/polishing machine.A window of dentine was exposed and subjected to a total of 1000 cycles of toothbrushing using a purpose made rotary toothbrushing machine.The surface profiles of the tooth specimens were assessed before and after toothbrushing with a Talysurf 2 Surface profilometer.RESULTS: The Chinese products generally showed greater abrasivity than many of the European products.CONCLUSION:Consideration should be given to the potential tooth wear that tested products may cause if used over longer periods as part of the preventive strategy to improve oral hygiene of patients.

  6. Microstructure and abrasive wear properties of M(Cr,Fe7C3 carbides reinforced high-chromium carbon coating produced by gas tungsten arc welding (GTAW process

    Soner BUYTOZ


    Full Text Available In the present study, high-chromium ferrochromium carbon hypereutectic alloy powder was coated on AISI 4340 steel by the gas tungsten arc welding (GTAW process. The coating layers were analyzed by optical microscopy, X-ray diffraction (XRD, field-emission scanning electron microscopy (FE-SEM, X-ray energy-dispersive spectroscopy (EDS. Depending on the gas tungsten arc welding pa-rameters, either hypoeutectic or hypereutectic microstructures were produced. Wear tests of the coatings were carried out on a pin-on-disc apparatus as function of contact load. Wear rates of the all coating layers were decreased as a function of the loading. The improvement of abrasive wear resistance of the coating layer could be attributed to the high hardness of the hypereutectic M7C3 carbides in the microstruc-ture. As a result, the microstructure of surface layers, hardness and abrasive wear behaviours showed different characteristics due to the gas tungsten arc welding parameters.

  7. Falling sand tests on various coatings

    Manetti, M.; Zonfrillo, G.; Pratesi, F. [Florence Univ. (Italy). Dipt. di Meccanica e Tecnologie Industriali; Giovannetti, I. [GE Oil and Gas - Nuovo Pilnone, Florence (Italy)


    Abrasive wear is responsible for severe machine parts and in particular of compressor impellers. Methods of increasing service lifetime are based on employment of abrasion resistant materials or more frequently of the creation of hard, wear-resistant surface layers. In this work a bare aluminium alloy and the same alloy with four different coatings have been tested at room temperature, in order to verify their resistance to falling abrasive. Following standard ASTM D968-93, tests have been performed using a precise quantity of sand as abrasive and letting it fall on the sample with a standard apparatus: two different kinds of sand have been used, in order to obtain also information on the influence of composition and Grain size of the abrasive on material resistance. Determinations of hardness, roughness, weight loss, and morphology of the eroded surface have also been carried out. The comparison between the coatings in vestilated has been performed on the basis of the thickness decrease of the samples. (orig.)

  8. Editor's Highlight: Abrasion of Artificial Stones as a New Cause of an Ancient Disease. Physicochemical Features and Cellular Responses.

    Pavan, Cristina; Polimeni, Manuela; Tomatis, Maura; Corazzari, Ingrid; Turci, Francesco; Ghigo, Dario; Fubini, Bice


    New outbursts of silicosis were recently reported among workers manufacturing an engineered material known as "artificial stone," composed by high percentages of quartz (up to 98%) agglomerated with pigments and polymeric resins. Dusts released by abrasion during artificial stone polishing were characterized for particle size, morphology, and elemental composition and studied for (1) ability to catalyze free radical generation in acellular tests, (2) membranolytic potential on human erythrocytes, (3) cytotoxic activity (lactate dehydrogenase release) on murine alveolar macrophages (MH-S) and human bronchial epithelial (BEAS-2B) cell lines, (4) induction of epithelial-mesenchymal transition (EMT) in BEAS-2B cells. Min-U-Sil 5 was used as reference quartz. Artificial stone dusts exhibited morphological features close to quartz, but contained larger amount of metal transition ions (mainly, Fe, Cu, and Ti), potentially responsible for the high reactivity in free radical generation observed. Opposite to Min-U-Sil 5, they were neither hemolytic nor cytotoxic on MH-S cells, a low cytotoxicity only being observed with BEAS-2B cells. The presence on the particle surface of residues of the resin accounts for this attenuated behavior, as hemolysis appeared and cytotoxicity increased after thermal degradation of the resin, when the free quartz surface was exposed. All dusts induced EMT with loss of E-cadherin expression and increased the expression of mesenchymal proteins (α-smooth muscle actin and vimentin). This may contribute to explain the development of fibrosis on workers exposed to artificial stone dusts.

  9. Massachusetts Beryllium Screening Program for Former Workers of Wyman-Gordon, Norton Abrasives, and MIT/Nuclear Metals

    Pepper, L. D.


    The overall objective of this project was to provide medical screening to former workers of Wyman-Gordon Company, Norton Abrasives, and MIT/Nuclear Metals (NMI) in order to prevent and minimize the health impact of diseases caused by site related workplace exposures to beryllium. The program was developed in response to a request by the U.S. Department of Energy (DOE) that had been authorized by Congress in Section 3162 of the 1993 Defense Authorization Act, urging the DOE to carry out a program for the identification and ongoing evaluation of current and former DOE employees who are subjected to significant health risks during such employment." This program, funded by the DOE, was an amendment to the medical surveillance program for former DOE workers at the Nevada Test Site (NTS). This program's scope included workers who had worked for organizations that provided beryllium products or materials to the DOE as part of their nuclear weapons program. These organizations have been identified as Beryllium Vendors.

  10. An abrasion-resistant and broadband antireflective silica coating by block copolymer assisted sol-gel method.

    Zou, Liping; Li, Xiaoguang; Zhang, Qinghua; Shen, Jun


    A double-layer broadband antireflective (AR) coating was prepared on glass substrate via sol-gel process using two kinds of acid-catalyzed TEOS-derived silica sols. The relative dense layer with a porosity of ∼10% was obtained from an as-prepared sol, while the porous layer with a porosity of ∼55% was from a modified one with block copolymer (BCP) Pluronic F127 as template which results in abundant ordered mesopores. The two layers give rise to a reasonable refractive index gradient from air to the substrate and thus high transmittance in a wide wavelength range, and both of them have the same tough skeleton despite different porosity, for which each single-layer and the double-layer coatings all behaved well in the mechanical property tests. The high transmittance and the strong ability of resisting abrasion make this coating promising for applications in some harsh conditions. In addition, the preparation is simple, low-cost, time-saving, and flexible for realizing the optical property.

  11. Effect of heat treatment on strength and abrasive wear behaviour of Al6061–SiCp composites

    N R Prabhu Swamy; C S Ramesh; T Chandrashekar


    In recent years, aluminum alloy based metal matrix composites (MMC) are gaining importance in several aerospace and automobile applications. Aluminum 6061 has been used as matrix material owing to its excellent mechanical properties coupled with good formability and its wide applications in industrial sector. Addition of SiCp as reinforcement in Al6061 alloy system improves its hardness, tensile strength and wear resistance. In the present investigation Al6061–SiCp composites was fabricated by liquid metallurgy route with percentages of SiCp varying from 4 wt% to 10 wt% in steps of 2 wt%. The cast matrix alloy and its composites have been subjected to solutionizing treatment at a temperature of 530°C for 1 h followed by quenching in different media such as air, water and ice. The quenched samples are then subjected to both natural and artificial ageing. Microstructural studies have been carried out to understand the nature of structure. Mechanical properties such as microhardness, tensile strength, and abrasive wear tests have been conducted both on matrix Al6061 and Al6061–SiCp composites before and after heat treatment. However, under identical heat treatment conditions, adopted Al6061–SiCp composites exhibited better microhardness and tensile strength reduced wear loss when compared with Al matrix alloy.

  12. Plaque growth-inhibiting effects of an abrasive fluoride-chlorhexidine toothpaste and a fluoride toothpaste containing oxidative enzymes.

    Etemadzadeh, H; Ainamo, J; Murtomaa, H


    The aim of this 4 times cross-over double-blind clinical trial was to test the plaque-inhibiting effect of 2 fluoride-containing toothpastes. One toothpaste contained 0.8% chlorhexidine together with amine fluoride (0.1% F degrees) and a suitable abrasive agent. The other contained 1.7 U/g glucose oxidase and 8.0 U/g amyloglucosidase, added to an amine fluoride (0.1% F degrees) toothpaste. 1% Hibitane dental gel was used as a positive and a conventional fluoride toothpaste (Vademecum MFP Fluor) as a negative control. 9 dental students, in a randomized sequence, applied the 4 dentifrices twice daily from Monday afternoon to Friday morning with cap splints, designed to cover the teeth and about 2 mm of gingiva. No other oral hygiene measures were allowed during the 4 test periods. On Fridays, the teeth were cleaned professionally and good oral hygiene was maintained during the week-ends. At the beginning and at the end of each test period, per student plaque thickness was recorded using the plaque index, the visible plaque index, and plaque fresh weight as parameters, and the area of plaque as related to the area of the tooth surface was recorded planimetrically and according to the PLQ index. The best plaque growth-inhibiting effect was recorded for the positive control (CHX) with the test chlorhexidine toothpaste (TX) as next best. The enzyme-containing toothpaste (TE) did not differ significantly from the negative control (C). All the significant differences in anti-plaque effect between the 4 toothpastes were obtained by recordings of plaque thickness and none on the basis of area of plaque.

  13. Study on ultra-precision magnetic abrasive finishing process using low frequency alternating magnetic field

    Wu, Jinzhong, E-mail:; Zou, Yanhua, E-mail:; Sugiyama, Hitoshi, E-mail:


    We proposed a new ultra-precision magnetic abrasive finishing (MAF) process using low frequency alternating magnetic field in this paper. Magnetic cluster themselves may produce the up and down movement change under alternating magnetic force. The movement may not only promote the dispersion of micro-magnetic particles, but also improve stirring effect and cross-cutting effects of the abrasives, achieving circulation and update to ensure the stability of grinding tools. This process is considered to be able to efficiently apply in ultra-precision finishing of plane and complicated micro-surfaces. In this study, we investigated the effects of alternating magnetic field on magnetic field distribution, finishing force and abrasive behavior. Furthermore, a set of experimental devices have been designed for finishing SUS304 stainless steel plate. The present work is aimed at understanding finishing particularity of this process and studying impacts of important process parameters namely grinding fluid, rotational speed of magnetic pole, current frequency on change in finish surface and material removal. Experimental results indicate that the process can realize ultra-precision finishing of plane by using oily grinding fluid. In the present research, the surface roughness of SUS304 stainless steel plate was improved from 240.24 nm to 4.38 nm by this process. - Highlights: • We investigated magnetic field distribution in processing region. • Magnetic cluster can produce a fluctuating finishing force in alternating magnetic field. • Oily grinding fluid is more applicable to this process. • Few nanometer finish surface can be obtained by this process.

  14. The unsteady nature of sea cliff retreat due to mechanical abrasion, failure and comminution feedbacks

    Kline, Shaun W.; Adams, Peter N.; Limber, Patrick W.


    Sea cliff retreat is often linked to large waves, heavy precipitation and seismic events, but the specific operative mechanics have not been well constrained. In particular, what is the role of mechanical abrasion by beach sediments in cliff/platform evolution and how does it relate to the episodic nature of cliff retreat observed at certain locations? Here we present a simple, numerical model of sea cliff retreat that incorporates mechanical abrasion of a basal notch, threshold-controlled failure of the cantilevered block, and a feedback mechanism wherein retreat is dependent on the rate of sediment comminution within the surf zone. Using shore platform and cliff characteristics found in two coastal settings (the central California coast and the English North Sea coast), the model produces retreat rates comparable to those observed via field measurements. The highest retreat rates coincide with the steepest shore platforms and increasing wave height. Steeper platforms promote wave access to the cliff toe and, correspondingly, the receding cliff face produces additional accommodation space for the platform beach, preserving the erosive efficacy of the beach sediments. When exposed to energetic wave forcing, the slope of the inner platform segment controls retreat rates for concave platforms, whereas the slope of the outer platform segment exerts greater control for convex platforms. Platform beaches approached a long-term dynamic equilibrium on the concave profiles, leading to more consistent and steady retreat. Platform beaches were ephemeral on convex profiles, mirroring observed sand wave (Ord) migration on the Holderness coast, UK. These findings agree with previous field observations and support mechanical abrasion as a viable cause of temporal heterogeneity in cliff retreat rate for both coastlines.

  15. Hydrothermal treatment for TiN as abrasion resistant dental implant coating and its fibroblast response

    Shi, Xingling, E-mail: [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Department of Biomaterials, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582 (Japan); Jiangsu Provincial Key Laboratory for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian 223003 (China); Xu, Lingli [School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003 (China); Munar, Melvin L.; Ishikawa, Kunio [Department of Biomaterials, Faculty of Dental Science, Kyushu University, Fukuoka 812-8582 (Japan)


    Dental implant made of pure titanium (Ti) is prone to scratch and abrasion during routine oral hygiene procedures. This results an increase in surface roughness and therefore, facilitates the adhesion of bacteria. In severe cases, this could lead to peri-implantitis. To overcome this problem, surface modification of Ti is necessary to improve its abrasion resistance. Besides, a strong implant–gingiva interface should also be guaranteed to prevent the adhesion of bacteria. In this study, titanium nitride (TiN) coating was first prepared with gas nitriding to increase surface hardness of pure the substrate. Then, the TiN was hydrothermally treated in CaCl{sub 2} solution in order to improve its soft tissue biocompatibility. The effect of hydrothermal treatment temperature on surface properties of TiN was investigated and its biocompatibility was assessed in vitro using NIH3T3 fibroblast cell. It was determined that 120 °C was the critical temperature for the hydrothermal treatment condition. Treatment below 120 °C could incorporate Ca into TiN surface, oxidize TiN surface partially and then improve the wettability while preserving its morphology and hardness. Fibroblast cell attachment and proliferation were improved and cell spreading was enhanced on hydrothermally treated specimens compared with untreated ones. Improved wettability, Ca incorporation and negative surface due to interstitial N were believed to be the main reasons. Hydrothermal treatment is expected to make TiN a promising dental implant coating with excellent abrasion resistance and good soft tissue affinity. - Highlights: • Ca was incorporated into TiN surface while not sacrificing its hardness. • Interstitial N due to oxidation promoted Ca adsorption and cell adhesion. • Hydrothermal treatment makes TiN a promising coating for dental implant.

  16. The microstructural aspects of abrasive wear resistance in composite electron beam clad coatings

    Gnyusov, S. F.; Tarasov, S. Yu.


    The effect of microstructure and phase composition of composite coatings based on manganese-containing or nickel-containing austenitic steel and containing either 10 wt.% TiC or 15 wt.% WC on the abrasive wear resistance has been studied. Both post-deposition heat treatment and self-aging in the course of deposition served to improve the relative wear resistance coefficient by 38-42 and 5-12% for Fe-20%Mn-4%V-4%Mo + 15%WC and Fe-20%Ni-4%V-4%Mo + 15%WC coatings, respectively.

  17. A comparison of material removal mechanism under low stress abrasive condition of steel and hardfacing alloys

    Dasgupta, R.; Prasad, B. K.; Modi, O. P.; Jha, A. K.


    The low stress abrasive wear behavior of two types of steels commonly used for making a number of commonly used engineering components has been compared with the composition of a few hardfacing alloys that can be overlayed on the steels to impart a wear-resistant surface. The mechanism of material removal as studied by the scanning electron micrographs of the worn and transverse sections is different for the steels and hardfacing alloys. An attempt has been made to explain the mechanism of material removal for the steels and hardfacing alloys.

  18. Experimental Study of Bedrock Incision Processes by Both Suspended Load and Bedload Abrasions

    Chatanantavet, P.; Whipple, K. X.; Adams, M. A.


    Channel incision into bedrock by both suspended load and bedload abrasions plays an important role in mountain landscape evolution. The study of erosion processes in both sediment transport regimes and their competition is therefore critical. Here we explored the dependence of experimental bedrock erosion rate on channel bed slope, water discharge, sediment flux, grain size, alluvial bed cover, and evolving channel morphology by slowly abrading weak concrete “bedrock.” In our flume, we are able to independently control bedload, suspended load, and water fluxes as well as channel slope. In the case of bedload, we also used a high-speed camera to track the saltation trajectories of coarse gravels on a smooth bed in another set of experiments and proposed new scaling relationships by including bed roughness and channel slope (separately from shear stress) for grain saltation velocity, height and length. In the case of bedload abrasion, we found that (1) all else held constant, erosion rate can (but not always) increase with channel slope in both smooth and rough bed conditions, (2) erosion rate increases with increasing grain size, and (3) erosion rate is insensitive to increasing water discharge. Thus shear stress is an inadequate metric for saltation dynamics and abrasion. In the case of suspended load abrasion, we found that (1) all else held constant, erosion occurred more in the planar bed condition than in the rough bed condition (deep grooves/slot canyons) because the erosion rate is strongly dependent on the near-bed flow (particle) velocity, (2) erosion rate increases with increasing sediment flux, and (3) perturbations (e.g., boulders) to the flow (thus creating turbulence/eddy) can greatly enhance the erosional efficiency. All else held constant (including bed morphology), the erosion rates by suspended load can account for 1.0 - 20 % (excluding the effect of flow perturbations) of those found in bedload erosion for the same sediment flux. Furthermore

  19. Experimental verification of characteristics of magnetic abrasive polishing combined with ultrasonic vibration

    Jin, Dong Hyun; Kwak, Jae Seob [Dept. of Mechanical Engineering, Pukyung National University, Busan (Korea, Republic of)


    In this paper, we propose an ultrasonic magnetic abrasive polishing (US-MAP) technique to effectively machine a high-strength material, and we prove the efficiency of hybrid finishing. We use Taguchi's experimental method to determine the influence of each parameter. Based on the results, US-MAP exhibited a higher polishing efficiency than traditional MAP, and a suitable frequency for hybrid finishing was 28 kHz. When investigating the effect of the parameters on the surface roughness, the ultrasonic amplitude had the greatest effect. However, when machining with 55-μm amplitude, the machining efficiency decreased as the magnetic flux density varied.


    I. Kachanov


    Full Text Available Investigations executed by the BNTU “Shipbuilding and hydraulics” department have shown that rather efficient implementation of the requirements to the metal sheet surface designed for laser cutting can be achieved by using hydro-abrasive jet cleaning while applying water pump equipment with the range of pressure – 20–40 MPa. Type of working fluid plays a significant role for obtaining surface of the required quality. The conducted experiments have demonstrated that the efficient solution of the assigned problems can be ensured by using a working fluid containing bentonite clay, surface-active agent polyacrylamide, soda ash and the rest water.

  1. Cut Front Geometry Characterization in Cutting Applications of Brass with Abrasive Water Jet

    Akkurt, Adnan


    Abrasive water jet (AWJ) cutting is an advanced manufacturing process for machining hard to cut materials. In this study, brass-353 samples of different thicknesses were cut by AWJ using different feed rates to identify the relationships between depth of cut (material thickness), feed rate, and deflection of cutting edge geometry. The effects of material thickness on the AWJ cut surface roughness were investigated and discussed. Deflection of cutting edge geometry in AWJ cutting process was assessed. Cutting edge geometry was characterized by analyzing the surface properties of cut samples.

  2. Development of a fixed abrasive slicing technique (FAST) for reducing the cost of photovoltaic wafers

    Schmid, F. (Crystal Systems, Inc., Salem, MA (United States))


    This report examines a wafer slicing technique developed by Crystal Systems, Inc. that reduces the cost of photovoltaic wafers. This fixed, abrasive slicing technique (FAST) uses a multiwire bladepack and a diamond-plated wirepack; water is the coolant. FAST is in the prototype production stage and reduces expendable material costs while retaining the advantages of a multiwire slurry technique. The cost analysis revealed that costs can be decreased by making more cuts per bladepack and slicing more wafers per linear inch. Researchers studied the degradation of bladepacks and increased wirepack life. 21 refs.

  3. The grain-size distribution of pyroclasts: Primary fragmentation, conduit sorting or abrasion?

    Kueppers, U.; Schauroth, J.; Taddeucci, J.


    Explosive volcanic eruptions expel a mixture of pyroclasts and lithics. Pyroclasts, fragments of the juvenile magma, record the state of the magma at fragmentation in terms of porosity and crystallinity. The grain size distribution of pyroclasts is generally considered to be a direct consequence of the conditions at magma fragmentation that is mainly driven by gas overpressure in bubbles, high shear rates, contact with external water or a combination of these factors. Stress exerted by any of these processes will lead to brittle fragmentation by overcoming the magma's relaxation timescale. As a consequence, most pyroclasts exhibit angular shapes. Upon magma fragmentation, the gas pyroclast mixture is accelerated upwards and eventually ejected from the vent. The total grain size distribution deposited is a function of fragmentation conditions and transport related sorting. Porous pyroclasts are very susceptible to abrasion by particle-particle or particle-conduit wall interaction. Accordingly, pyroclastic fall deposits with angular clasts should proof a low particle abrasion upon contact to other surfaces. In an attempt to constrain the degree of particle interaction during conduit flow, monomodal batches of washed pyroclasts have been accelerated upwards by rapid decompression and subsequently investigated for their grain size distribution. In our set-up, we used a vertical cylindrical tube without surface roughness as conduit. We varied grain size (0.125-0.25; 0.5-1; 1-2 mm), porosity (0; 10; 30 %), gas-particle ratio (10 and 40%), conduit length (10 and 28 cm) and conduit diameter (2.5 and 6 cm). All ejected particles were collected after settling at the base of a 3.3 m high tank and sieved at one sieve size below starting size (half-Φ). Grain size reduction showed a positive correlation with starting grain size, porosity and overpressure at the vent. Although milling in a volcanic conduit may take place, porous pyroclasts are very likely to be a primary product

  4. Extrude Honing Abrasive Slurry and Its Honing Experiments for Fuel Jet Nozzle%喷油嘴微喷孔挤压研磨液及其试验研究

    黄颖; 张向军; 李勇; 李晓民


    The abrasive flow machining has become a key process for the advanced diesel engines to finish the final surface of fuel injector nozzle. Abrasive slurry was compounded by the method of oil-water emulsion. According to the principles of abrasive flow machining, a kind of abrasive slurry with good performance in suspension and cutting was explored and compounded, whose abrasive particles are brown alumina, and particle size range is 0. 4~50 μm. In addition, a test -bed was built for extruding honing the fuel injector nozzle. Then, the variations of the flow coefficient were measured and a series of the process parameters involved in the extruding honing technology for the fuel injector nozzle were studied experimentally. The injector nozzles were extruding honed under different times and pressures. With the increase of processing time, the effect was gradually saturated. With the increese of pressure, the wear of the device was serious. Tes-ting results indicated that 5 min and 10 Mpa are the best process parameters. The fuel injector nozzles were reamed in the process but didn't exceed 2%.%挤压研磨工艺已经成为高端柴油机喷油嘴微喷孔加工的最终表面成形的关键工序.根据磨料流加工的原理采用油水乳浊液的方式,配制了具有良好分散性能和切削性能的研磨剂,其磨料颗粒为棕刚玉,粒度范围0.4~50 μm,搭建了喷油嘴微喷孔挤压研磨的试验台,测量其流量因数的变化,对喷油嘴微喷孔挤压研磨工艺中的时间、压力因素进行了试验研究.随加工时间增加,研磨效果趋于饱和,随加工压力增加,对设备磨损加剧,试验结果表明,加工时间5 min,加工压力10 MPa为最佳工艺参数.挤压研磨过程中,造成了喷油嘴微喷孔孔径的扩大,但是不超过2%.

  5. Test

    Bendixen, Carsten


    Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers.......Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers....

  6. Effect of Pressure, Feed Rate, and Abrasive Mass Flow Rate on Water Jet Cutting Efficiency When Cutting Recombinant Bamboo

    Rongrong Li


    Full Text Available The impact of varying pressure, feed rate, and abrasive mass flow rate on the efficiency of an abrasive water jet cutting process was studied in this work. Recombinant bamboo samples with thicknesses of 5, 10, and 15 mm were cut by the abrasive water jet. The upper kerf width, lower kerf width, and the ratio of the upper kerf width to lower kerf width were chosen as the efficiency parameters. Mathematical models were developed to describe the relationship between the input process parameters and the efficiency parameters. The arrangement of experiments and analysis of results were performed based on response surface methodology. The evaluated model yielded predictions in agreement with experimental results.



    This paper presents an alternate method to re-move the sand carried by natural gas in the upstream pipelinestherefore preventing sand abrasive erosion in pipelines used intransporting high-speed natural gas. Conventionally, most ex-perts pay much attention to improving the anti-erosion charac-teristics of the pipeline materials to solve the problem of seri-ous abrasive erosion, but without significant success. Basedon the theory of multiphase flow and analysis of the character-istics of sandy jets, a new equipment named "Sand Catcher" isintroduced in this article. Experimental results show that theSand Catcher effectively removes most of the sand in the natu-ral gas and significantly reduces the abrasive erosion of thepipelines. The Sand Catcher can be widely applied in practicein the near future.

  8. Comparative study for surface topography of bone drilling using conventional drilling and loose abrasive machining.

    Singh, Gurmeet; Jain, Vivek; Gupta, Dheeraj


    Drilling through the bone is a complicated process in orthopaedic surgery. It involves human as a part of the work so it needs better perfection and quality which leads to the sustainability. Different studies were carried out on this curious topic and some interesting results were obtained, which help the orthopaedic surgeon on the operation table. Major problems faced during bone drilling were crack initiation, thermal necrosis and burr formation. The surface topography of the bone is an indirect indication for the sustainability of bone joint. In this study, a comparison is made between conventional and a loose abrasive unconventional drilling technique for the surface characterization of the bone. The attempt has been made to show the feasibility of bone drilling with non-conventional technique and its aftereffect on the bone structure. The burr formation during conventional bone drilling was found to be more which leads to problems such as crack initiation and thermal necrosis. Scanning electrode microscope and surface roughness tester were used to characterize the surface of the fine drilled bone specimen and the results testified quite better surface finish and least crack formation while drilling with loose abrasive unconventional technique.

  9. U-Pb dating by zircon dissolution method using chemical abrasion

    Takehara, Lucy, E-mail: [Servico Geologico do Brasil (CPRM), Brasilia, DF (Brazil); Chemale Junior, Farid [Universidade de Brasilia (UnB), Brasilia, DF (Brazil). Inst. de Geociencias. Lab. de Geocronologia; Hartmann, Leo A. [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil). Inst. de Geociencias; Dussin, Ivo A.; Kawashita, Koji [Universidade de Sao Paulo (USP), SP, (Brazil). Centro de Pesquisa Geocronologicas


    Chemical abrasion was carried out on zircons grains of the Temora II standard for U-Pb dating prior to analyses using in situ Laser Ablation-Multi Collector Ion Coupled Plasma Mass Spectrometer (LA-ICPMS) followed by the Isotope Dissolution Thermal Ionization Mass Spectrometer (ID-TIMS) method. The proposed methodology was herein applied in order to reduce primarily the effects of secondary Pb loss, the presence of common lead and/or silicate impurities. Nine Temora II zircon grains were analyzed by the laser ablation method yielding an age of 418.3 +- 4.3 Ma. Zircon grains of a same population were separated for chemical abrasion before dissolution and mass spectrometry analyses. Six fractions of them were separated for isotope dissolution using {sup 235}U-{sup 205}Pb mixed spike after we have checked and assured the laboratory conditions of low blank values for total Pb of less than 2 pg/g. The obtained U-Pb zircon age by the ID-TIMS method was 415.7 +- 1.8 Ma (error 0.43 %) based on four successful determinations. The results are consistent with the published ages for the Temora diorite (Temora I - 416.75 +- 1.3 Ma; Temora II - 416.78 +- 0.33 Ma) and established as 416 +- 0.33 Ma. The technique is thus recommended for high precision U-Pb zircon analyses (error < 1 %), mainly for high resolution stratigraphic studies of Phanerozoic sequences. (author)

  10. Management of gingiva hyperpigmentasi with combine of scalpel scraping technique and gingivo abrasion technique (Case report

    Shek Wendy


    Full Text Available Aesthetic factor is an important factor in supporting the person's appearance, especially when a person smiles. Beautifull smiles form of harmonization between the teeth and gums as part of the oral cavity. One of overall aspect that has an important role in providing the overall aesthetic impression is normal gum color that pink coral. Brown or black gums are often become the complaint that interfere with appearance, especially in patients who have a habit of smoking. Pigmentation caused by melanin hyperpigmentation and usually does not present a medical problems, so patients are not aware of it. Surgical method with the scalpel scraping technique and gingivo abrasion technique using high speed carbide bur has been widely used as a method of gingival depigmentation. This method is easily done, simple and can be done in a relatively short time. In this case report presented regarding the management of patients with gingival hyperpigmentation of the maxilla and mandible were treated with surgical method using a scalpel scraping technique combined with gingivo abrasion technique using high speed carbide bur. The result, after 4 weeks follow up, color of the patient's gingival was pink and there is none recurrence of the pigmentation.

  11. Experimental Study on the Effects of Alumina Abrasive Particle Behavior in MR Polishing for MEMS Applications

    Young-Jae Shin


    Full Text Available Recently, the magnetorheological (MR polishing process has been examined asa new ultra-precision polishing technology for micro parts in MEMS applications. In theMR polishing process, the magnetic force plays a dominant role. This method uses MRfluids which contains micro abrasives as a polishing media. The objective of the presentresearch is to shed light onto the material removal mechanism under various slurryconditions for polishing and to investigate surface characteristics, including shape analysisand surface roughness measurement, of spots obtained from the MR polishing process usingalumina abrasives. A series of basic experiments were first performed to determine theoptimum polishing conditions for BK7 glass using prepared slurries by changing the processparameters, such as wheel rotating speed and electric current. Using the obtained results,groove polishing was then performed and the results are investigated. Outstanding surfaceroughness of Ra=3.8nm was obtained on the BK7 glass specimen. The present resultshighlight the possibility of applying this polishing method to ultra-precision micro partsproduction, especially in MEMS applications.

  12. Controlled wear of vitrified abrasive materials for precision grinding applications

    M J Jackson; B Mills; M P Hitchiner


    The study of bonding hard materials such as aluminium oxide and cubic boron nitride (BN) and the nature of interfacial cohesion between these materials and glass is very important from the perspective of high precision grinding. Vitrified grinding wheels are typically used to remove large volumes of metal and to produce components with very high tolerances. It is expected that the same grinding wheel is used for both rough and finish machining operations. Therefore, the grinding wheel, and in particular its bonding system, is expected to react differently to a variety of machining operations. In order to maintain the integrity of the grinding wheel, the bonding system that is used to hold abrasive grains in place reacts differently to forces that are placed on individual bonding bridges. This paper examines the role of vitrification heat treatment on the development of strength between abrasive grains and bonding bridges, and the nature of fracture and wear in vitrified grinding wheels that are used for precision grinding applications.

  13. Ultra-precision ductile grinding of BK7 using super abrasive diamond wheel

    ZHAO Qingliang; Brinksmeier Ekkard; Riemer Oltmann; Rickens Kai


    In this paper,a novel conditioning technique using copper bonded diamond grinding wheels of 91 μm grain size and electrolytic in-process dressing (ELID) is first developed to precisely and effectively condition a nickelelectroplated monolayer coarse-grained diamond grinding wheel of 151 μm grain size.Under optimised conditioning parameters,the super abrasive diamond wheel was well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope.The conditioning force was monitored by a force transducer,while the modified wheel surface status was in-situ monitored by a coaxial optical distance measurement system.Finally,the grinding experiment on BK7 was conducted using the well-conditioned wheel with the corresponding surface morphology and subsurface damage measured by atomic force microscope (AFM) and scanning electric microscope (SEM),respectively.The experimental result shows that the newly developed conditioning technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness,indicating the potential of super abrasive diamond wheels in ductile machining brittle materials.

  14. Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion

    Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina


    The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (pmeasurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.

  15. Measurements of traffic-induced abrasion particles in a Swiss city

    Furger, M.; Amato, F.; Bukowiecki, N.


    Particle emissions from road traffic can be divided into two basic categories: i) emissions due to fuel combustion, ii) emissions due to abrasion and mechanical wear of the brakes, the engine, the tires, and the road surface. The three-year project APART was focused on the latter, and measurements took place mainly in the city of Zurich, Switzerland. Several campaigns on and in the vicinity of roads with different traffic characteristics were performed between 2006 and 2008, covering different seasons and weather conditions. Air-borne, deposited and re-suspended particles were collected at fixed locations and with a mobile laboratory, and subsequently chemically analyzed. Vehicle abrasion particles consisted mainly of Fe, Cu, Mo, Sn, Sb and Ba. Road dust samples were composed mainly of organic and elemental carbon and some crustal elements (Si, Ca, Fe, Al, K, Mg), with traces of Cu, Zn, Ba, and Ti. The transport distance of the particles was investigated with aerodynamic particle sizer (APS) measurements at varying distances from a freeway. Furthermore the dependence of re-suspension on traffic density was investigated. This study was funded by the Swiss Federal Roads Authority (ASTRA), the Swiss Federal Office for the Environment (BAFU), and by the Spanish Ministry of Science and Innovation (GRACCIE-SCD2007-00067).

  16. Simulation of abrasive water jet cutting process: Part 1. Unit event approach

    Lebar, Andrej; Junkar, Mihael


    Abrasive water jet (AWJ) machined surfaces exhibit the texture typical of machining with high energy density beam processing technologies. It has a superior surface quality in the upper region and rough surface in the lower zone with pronounced texture marks called striations. The nature of the mechanisms involved in the domain of AWJ machining is still not well understood but is essential for AWJ control improvement. In this paper, the development of an AWJ machining simulation is reported on. It is based on an AWJ process unit event, which in this case represents the impact of a particular abrasive grain. The geometrical characteristics of the unit event are measured on a physical model of the AWJ process. The measured dependences and the proposed model relations are then implemented in the AWJ machining process simulation. The obtained results are in good agreement in the engraving regime of AWJ machining. To expand the validity of the simulation further, a cellular automata approach is explored in the second part of the paper.

  17. Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion.

    Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina


    The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (pmeasurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.

  18. An Assessment on the Production of Abrasive Sandpaper from Locally Sourced Materials

    M.U. Obot


    Full Text Available A comparative analysis of abrasive sandpaper made from two locally sourced and easily available materials, periwinkle and palm kernel shells was carried out to evaluate their viability as replacements for foreign imported abrasives sandpaper. Composites of crushed shells with polyester resin bond were developed separately for the periwinkle and palm kernel shell samples using mould compression, and the sandpaper prototype was produced using hand-spray method. A study on the physico-mechanical properties of the produced composite carried out was found that at 12 wt.% content of resin, periwinkle shell (PWS/resin composites had higher physico-mechanical properties such as density with 77.74 % difference, hardness with 17.13 % difference and compressive strength with 182.42 % difference over the palm kernel shell-resin composites. Water absorption for palm kernel (PKS shell/resin composite was a 186.59 % difference over the PWS/resin composite. Surface morphology using SEM revealed PWS/resin composite to have less distortional effects on the grains from compressive force of 15.7 N/mm2 applied compared to the palm kernel shell grains, and also shows PWS grains held together in close packing by the resin bond. The concentration used for sandpaper production was 87 wt.% of periwinkle shell grains to 12 wt.% of resin. The obtained physical and mechanical properties were compared to garnet sandpaper and found to be close to acceptable standards.

  19. Technologies and experience with monitoring sediments for protecting turbines from abrasion

    Agrawal, Y.; Slade, W.; Pottsmith, C.; Dana, D.


    Abrasion of turbines by sediments is a constant threat in high head and high sediment load situations. It is widely recognized that larger grains cause abrasion, although no consensus on a critical size exists. Grain hardness plays a second key role. Thus monitoring of sediment concentration is highly desirable, particularly with attention paid to the large grains. This has recently become possible with LISST instruments that use laser diffraction (LD) technology. These in-line instruments measure multi-angle laser light scattering, which is converted to a particle size distribution in a pre-defined size range. In order to reach high concentrations, the instruments incorporate auto-dilution capability. The data are transmitted to the control room. Provided software displays concentration history in up to 4 size classes, and the software is capable of generating alarms when sufficiently high concentrations occur. Since no definition exists for this sufficiently high concentration, in this paper we propose an objective criterion based on the rate of revenue generation contrasted with rate of cost of turbine repair. This simple idea helps guide the plant operator to set shut-down thresholds during sediment transport events. We also introduce a lower cost, high-frequency pulsed acoustic sensor for sediment monitoring. The rather lower accuracy of this device is offset by its lower cost that is suitable for small plants.

  20. Improvement of finishing antifriction treatment without abrasive of the rubbing parts surfaces of agricultural machineries

    I.V. Shepelenk


    Full Text Available The wear of machines and mechanisms after rubbing is a major concern. The costs of manufacturing and restoration parts for agricultural machinery are enormous such as the trunnions pinions of hydraulic pumps. Finishing treatment antifriction without abrasive (FTAA is the existing method of manufacturing and restoration, but it has disadvantages like low work efficiency and the frequent replacement of the instrument. That is why a new method of FTAA parts type ''tree'' has been developed called vibratory finishing treatment antifriction without abrasive, (VFTAA method. The study was conducted at the laboratory of the State Technical University of Kirovograd (Ukraine where turn 16K20, the profilograph-profilometer "Talysurf-5", the scanning electron microscope REM-106I, friction machine MI-1M and the stand KI-28097-02M were used respectively for machining, study of micro relief before and after the VFTAA, microstructure, wear resistance and the determination of the break-in period of parts. The results showed that the VFTAA helped reduce the roughness Ra of the samples studied by half compared to the samples processed by polishing and 1.3 times compared to those treated with the FTAA, the break-in period has been reduced four times , this leads to an increase in the life of the hydraulic pump. This technology can be recommended for manufacturing and repair of hydraulic units of agricultural machineries.

  1. Experimental investigation of abrasive electrodischarge grinding of Ti6Al4V titanium alloy

    R. Święcik


    Full Text Available Purpose: This work is focused on determination of effects of grinding conditions on effectiveness of abrasive electrodischarge grinding (AEDG process applied for removal of machining allowance and forming of surface geometrical texture (SGT. These results were compared with one obtained for conventional grinding.Design/methodology/approach: The experimental investigations of deep-seated surface grinding of Ti6Al4V titanium alloy using CBN grinding wheel with metal bond were the ground for this elaboration. The effectiveness of AEDG process was assessed based on specific tangential grinding force and energy of spark electric discharge and machining results were estimated on geometrical structure parameters.Findings: The effectiveness of machining allowance removal depended on conditions of AEDG process. Significant differences in SGT formed by AEDG process and conventional grinding were revealed.Practical implications: Abrasive electrodischarge grinding is useful to be particularly suitable for efficient and effective grinding of very hard structural materials such as high-alloy steel, sintered carbides, metal-based composite materials etc.Originality/value: AEDG experiments were carried out using the typical surface finishing grinder and especially adapted generator of spark discharge pulses. The majority of such experiments in the world were performed with the electrodischarge machine tool equipped with extra grinding wheel mounted on the grinding pin and functioning as one of the electrodes put into operation via pneumatic drive.

  2. Effects of air abrasion with alumina or glass beads on surface characteristics of CAD/CAM composite materials and the bond strength of resin cements

    ARAO Nobuaki


    Full Text Available ABSTRACT Objective The study aimed to evaluate effects of air abrasion with alumina or glass beads on bond strengths of resin cements to CAD/CAM composite materials. Material and Methods CAD/CAM composite block materials [Cerasmart (CS and Block HC (BHC] were pretreated as follows: (a no treatment (None, (b application of a ceramic primer (CP, (c alumina-blasting at 0.2 MPa (AB, (d AB followed by CP (AB+CP, and (e glass-beads blasting at 0.4 MPa (GBB followed by CP (GBB+CP. The composite specimens were bonded to resin composite disks using resin cements [G-CEM Cerasmart (GCCS and ResiCem (RC]. The bond strengths after 24 h (TC 0 and after thermal cycling (TC 10,000 at 4–60°C were measured by shear tests. Three-way ANOVA and the Tukey compromise post hoc tests were used to analyze statistically significant differences between groups (α=0.05. Results For both CAD/CAM composite materials, the None group exhibited a significant decrease in bond strength after TC 10,000 (p0.05. The AB+CP group showed a significantly higher bond strength after TC 10,000 than did the AB group for RC (p<0.05, but not for GCCS. The GBB+CP group showed the highest bond strength for both thermal cyclings (p<0.05. Conclusions Air abrasion with glass beads was more effective in increasing bond durability between the resin cements and CAD/CAM composite materials than was using an alumina powder and a CP.

  3. Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

    Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu


    20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

  4. Studies on parametric optimization for abrasive water jet machining of Al7075-TiB2 in-situ composite

    Kavya, J. T.; Keshavamurthy, R.; Pradeep Kumar, G. S.


    The study focuses on optimization and determination of significant process parameter for Abrasive Water Jet Machining of Al7075-TiB2metal matrix composite. Al-TiB2 metal matrix composite is synthesized by stir casting using in-situ technique. Optimization of machining parameters is done using Taguchi's L25orthogonal array for the experimental trials, with cutting speed, stand-off distance and Abrasive Flow rate as input parameters at five different levels. Analysis Of Variance (ANOVA) method is used for identifying the effect of machining parameters on volumetric material removal rate, surface roughness and dimensional accuracy. Then the results are validated by conducting verification experiments.

  5. Abrasive Wear of Laser Surface Hardened 9SiCr in Soils%激光硬化9SiCr表面土壤磨损研究

    陈卓君; 张祖立


    Abrasive wear tests of laser treated 9SiCr blade were conducted using three kinds of abrasives ( loam soil, sand soil and clay soil). The parameters of laser treatment (e. g. laser power 1 200 W, scanning velocity 14 mm/s, laser power 1 500 W, scanning velocity 16 mm/s) were optimized to obtain the hard and wear resistant surface on 9SiCr blade. Wear resistances of laser treated 9SiCr blade in three kinds of soils were measured and compared. The wear resistance of laser hardened 9SiCr steel blade was 5 times as high as that of quenched 9SiCr steel blade. The main wear mechanism of laser hardened 9SiCr blade in soil was abrasive wear. By improving the hardness, the wear lifetime of laser hardened 9SiCr blade was prompted.%在壤土、沙土和黏土3种土壤中对激光处理的9SiCr材料进行磨损试验,考察了激光硬化工艺参数对9SiCr旋耕刀基体显微硬度的影响,获得9SiCr旋耕刀基体激光硬化处理的最佳工艺参数.结果表明:在激光功率为1 200 W、扫描速度为14 mm/s和激光功率1 500 W、扫描速度16 mm/s的条件下,磨损率较小.激光处理表面在3种土壤条件下进行了耐磨性比较,沙土对试件的磨损率影响最小.9SiCr经过激光处理其表面耐磨性比一般淬火表面的耐磨性提高约5倍.9Sicr表面磨损形式主要是磨粒磨损.激光处理9SiCr表面提高了表面硬化层的硬度,从而提高了材料的耐磨性,增加了9SiCr的使用寿命.

  6. Structural transformations of amorphous iron-based alloys upon abrasive and thermal treatments

    Korshunov, L. G.; Shabashov, V. A.; Litvinov, A. V.; Chernenko, N. L.


    Wear resistance and structural changes have been investigated in amorphous alloys Fe64Co30Si3B3 and Fe73.5Nb3Cu1Si13.5B9 upon wear using a fixed abrasive. The structural studies have been performed by the methods of metallography, electron microscopy, and Mössbauer spectroscopy. It has been shown that the abrasive resistance of amorphous alloys is 1.6-3.1 times lower than that of high-carbon tool steels, which have a close level of hardness. The low abrasive wear resistance of amorphous alloys is caused by the deformation softening of the alloy surface in the process of wear. The major volume of the deformed surface layer of the alloys preserves the amorphous state. Its structural changes upon wear are characterized by the formation of inhomogeneities (fragments with a size of 10-50 nm) and by a decrease in the width of the strongest “halo” in the selected-area electron-diffractions patterns. In the amorphous matrix of the Fe64Co30Si3B3 alloy, a strong magnetic texture is formed and a redistribution of atoms occurs, which leads to an increase in the local shortrange order corresponding to FeB, Fe2B, Fe3B and α-Fe phases. In microvolumes of a thin (several μm) surface layer, the formation of a nanocrystalline structure (on the order of several volume %) was revealed. A tempering of the Fe73.5Cu1Nb3S13.5B9 alloy at temperatures below 500°C does not affect the hardness and wear resistance of the alloy. At 500°C, there occurs an increase in microhardness and wear resistance of the Fe73.5Cu1Nb3S13.5B9 alloy as a result of the formation in it of a nanocrystalline structure with the retention of a certain amount of the amorphous phase. The complete crystallization of the alloy at 540°C increases the brittleness of the alloy, which leads to a sharp reduction in its wear resistance.

  7. Lab-scale ash production by abrasion and collision experiments of porous volcanic samples

    Mueller, S. B.; Lane, S. J.; Kueppers, U.


    In the course of explosive eruptions, magma is fragmented into smaller pieces by a plethora of processes before and during deposition. Volcanic ash, fragments smaller than 2 mm, has near-volcano effects (e.g. increasing mobility of PDCs, threat to human infrastructure) but may also cause various problems over long duration and/or far away from the source (human health and aviation matters). We quantify the efficiency of ash generation during experimental fracturing of pumiceous and scoriaceous samples subjected to shear and normal stress fields. Experiments were designed to produce ash by overcoming the yield strength of samples from Tenerife (Canary Islands, Spain), Sicily and Lipari Islands (Italy), with this study having particular interest in the < 355 μm fraction. Fracturing within volcanic conduits, plumes and pyroclastic density currents (PDCs) was simulated through a series of abrasion (shear) and collision (normal) experiments. An understanding of these processes is crucial as they are capable of producing very fine ash (< 10 μm). These particles can remain in the atmosphere for several days and may travel large distances (~ 1000s of km). This poses a threat to the aviation industry and human health. From the experiments we establish that abrasion produced the finest-grained material and up to 50% of the generated ash was smaller than 10 μm. In comparison, the collision experiments that applied mainly normal stress fields produced coarser grain sizes. Results were compared to established grain size distributions for natural fall and PDC deposits and good correlation was found. Energies involved in collision and abrasion experiments were calculated and showed an exponential correlation with ash production rate. Projecting these experimental results into the volcanic environment, the greatest amounts of ash are produced in the most energetic and turbulent regions of volcanic flows, which are proximal to the vent. Finest grain sizes are produced in PDCs

  8. Abrasion and fatigue resistance of PDMS containing multiblock polyurethanes after accelerated water exposure at elevated temperature.

    Chaffin, Kimberly A; Wilson, Charles L; Himes, Adam K; Dawson, James W; Haddad, Tarek D; Buckalew, Adam J; Miller, Jennifer P; Untereker, Darrel F; Simha, Narendra K


    Segmented polyurethane multiblock polymers containing polydimethylsiloxane and polyether soft segments form tough and easily processed thermoplastic elastomers (PDMS-urethanes). Two commercially available examples, PurSil 35 (denoted as P35) and Elast-Eon E2A (denoted as E2A), were evaluated for abrasion and fatigue resistance after immersion in 85 °C buffered water for up to 80 weeks. We previously reported that water exposure in these experiments resulted in a molar mass reduction, where the kinetics of the hydrolysis reaction is supported by a straight forward Arrhenius analysis over a range of accelerated temperatures (37-85 °C). We also showed that the ultimate tensile properties of P35 and E2A were significantly compromised when the molar mass was reduced. Here, we show that the reduction in molar mass also correlated with a reduction in both the abrasion and fatigue resistance. The instantaneous wear rate of both P35 and E2A, when exposed to the reciprocating motion of an ethylene tetrafluoroethylene (ETFE) jacketed cable, increased with the inverse of the number averaged molar mass (1/Mn). Both materials showed a change in the wear surface when the number-averaged molar mass was reduced to ≈ 16 kg/mole, where a smooth wear surface transitioned to a 'spalling-like' pattern, leaving the wear surface with ≈ 0.3 mm cracks that propagated beyond the contact surface. The fatigue crack growth rate for P35 and E2A also increased in proportion to 1/Mn, after the molar mass was reduced below a critical value of ≈30 kg/mole. Interestingly, this critical molar mass coincided with that at which the single cycle stress-strain response changed from strain hardening to strain softening. The changes in both abrasion and fatigue resistance, key predictors for long term reliability of cardiac leads, after exposure of this class of PDMS-urethanes to water suggests that these materials are susceptible to mechanical compromise in vivo.

  9. A blue-LED-based device for selective photocoagulation of superficial abrasions: theoretical modeling and in vivo validation

    Rossi, Francesca; Pini, Roberto; De Siena, Gaetano; Massi, Daniela; Pavone, Francesco S.; Alfieri, Domenico; Cannarozzo, Giovanni


    The blue light (~400 nm) emitted by high power Light Emitting Diodes (LED) is selectively absorbed by the haemoglobin content of blood and then converted into heat. This is the basic concept in setting up a compact, low-cost, and easy-to-handle photohaemostasis device for the treatment of superficial skin abrasions. Its main application is in reducing bleeding from superficial capillary vessels during laser induced aesthetic treatments, such as skin resurfacing, thus reducing the treatment time and improving aesthetic results (reduction of scar formation). In this work we firstly present the preliminary modeling study: a Finite Element Model (FEM) of the LED induced photothermal process was set up, in order to estimate the optimal wavelength and treatment time, by studying the temperature dynamics in the tissue. Then, a compact, handheld illumination device has been designed: commercially available high power LEDs emitting in the blue region were mounted in a suitable and ergonomic case. The prototype was tested in the treatment of dorsal excoriations in rats. Thermal effects were monitored by an infrared thermocamera, experimentally evidencing the modest and confined heating effects and confirming the modeling predictions. Objective observations and histopathological analysis performed in a follow-up study showed no adverse reactions and no thermal damage in the treated areas and surrounding tissues. The device was then used in human patients, in order to stop bleeding during Erbium laser skin resurfacing procedure. By inducing LED-based photocoagulation, the overall treatment time was shortened and scar formation was reduced, thus enhancing esthetic effect of the laser procedure.

  10. 便携式磨料水射流切割系统设计%Design of Portable Abrasive Water Jet Cutting System

    陈晓晨; 邓松圣; 于以兵; 廖松


    In order to improve the efficiency and safety of oil depot emergency repair, an abrasive water jet cutting (AWJC) technology is adopted for fast cutting under the conditions of high concentration of oil and gas. Through the optimal design of the pipeline system, abrasive add system and power system, a kind of portable AWJC system which is suitable for oil depot emergency repair cutting is assembled. Cutting tests for X60 pipeline steel are carried out by using this system, and a cutting model is obtained which would be used to guide the cutting operation of oil pipeline effectively. All of these researches will promote the application of portable AWJC technology and can effectively improve the efficiency of oil depot emergency repair.%为提高油库应急抢修效率及安全性,利用磨料水射流切割技术在高油气浓度下直接对油库破损待修设备进行快速切割。通过对磨料水射流切割系统进行研究,设计优化了管路系统、磨料添加系统和动力系统,得到了适用于油库应急抢修切割操作的便携式磨料水射流切割系统样机。使用样机对X60管线钢进行切割试验,得到了切割模型,该模型能够有效指导油库管道抢修切割操作。研究为磨料水射流切割技术在油库应急抢修切割中的应用奠定了基础。

  11. Abrasive Wear Behavior of WC Reinforced Ni-BASED Composite Coating Sprayed and Fused by Oxy-Acetylene Flame

    Wang, Qun; Chen, Zhenhua; Ding, Zhang Xiong; Chen, Ding

    Microstructure of WC reinforced Ni-based self-fluxing alloy composite coating sprayed and fused by oxy-acetylene flame was investigated by scanning electron microscopy and energy dispersive X-ray Spectrometry, X-ray diffraction, and transmission electron microscopy. The wear performance of the coating was studied by a MLS-225 wet sand rubber wheel abrasive wear tester at various loads and sizes of abrasive particles. Also, the wear resistance of the coating was compared with uncoated ASTM1020 steel. The results indicated that the coating is bonded metallurgically to the substrate and has a homogeneous microstructure composed of both coarse WC and fine carbide and boride grains such as Cr7C3, Cr23C6, and Ni2B which disperse uniformly in the matrix of γ-Ni solid solution and Ni3B. The worn mass loss of the coating and ASTM1020 steel both increased with the load and size of abrasive particles, also, the coating has exhibited excellent abrasive wear resistance compared with ASTM1020 steel.

  12. Deposition of TiC film on titanium for abrasion resistant implant material by ion-enhanced triode plasma CVD

    Zhu Yuhe, E-mail: [School of Stomatology, China Medical University, Shen Yang (China); Wang Wei; Jia Xingya [School of Stomatology, China Medical University, Shen Yang (China); Akasaka, Tsukasa [Department of Health Science, School of Dental Medicine Hokkaido University, Sapporo (Japan); Liao, Susan [School of Materials Science and Engineering, Nanyang Technological University (Singapore); Watari, Fumio [Department of Health Science, School of Dental Medicine Hokkaido University, Sapporo (Japan)


    Highlights: Black-Right-Pointing-Pointer Deposition of Titanium Carbide (TiC) layer on titanium (Ti) surface has been demonstrated by an ion-enhanced triode plasma chemical vapor deposition (CVD) method. Black-Right-Pointing-Pointer The Vickers hardness of surface carbide was more than 2000, which confirmed its high abrasion resistance. Black-Right-Pointing-Pointer Physical and mechanical properties of the deposited TiC film on Ti were investigated to examine its potential application as an abrasion resistant implant material. - Abstract: Deposition of titanium carbide (TiC) layer on titanium (Ti) surface has been demonstrated by an ion-enhanced triode plasma chemical vapor deposition (CVD) method using a TiCl{sub 4} + CH{sub 4} + H{sub 2} gas mixture. Physical and mechanical properties of the deposited TiC film on Ti were investigated to examine its potential application as an abrasion resistant implant material. X-ray diffraction (XRD) showed that the specimen was consisted of TiC and Ti. Carbide layer of about 6 {mu}m thickness was observed on the cross section of the specimen by scanning electron microscopy (SEM). The Vickers hardness of surface carbide was more than 2000, which confirmed its high abrasion resistance.

  13. Small-Scale Morphological Features on a Solid Surface Processed by High-Pressure Abrasive Water Jet

    Can Kang


    Full Text Available Being subjected to a high-pressure abrasive water jet, solid samples will experience an essential variation of both internal stress and physical characteristics, which is closely associated with the kinetic energy attached to the abrasive particles involved in the jet stream. Here, experiments were performed, with particular emphasis being placed on the kinetic energy attenuation and turbulent features in the jet stream. At jet pressure of 260 MPa, mean velocity and root-mean-square (RMS velocity on two jet-stream sections were acquired by utilizing the phase Doppler anemometry (PDA technique. A jet-cutting experiment was then carried out with Al-Mg alloy samples being cut by an abrasive water jet. Morphological features and roughness on the cut surface were quantitatively examined through scanning electron microscopy (SEM and optical profiling techniques. The results indicate that the high-pressure water jet is characterized by remarkably high mean flow velocities and distinct velocity fluctuations. Those irregular pits and grooves on the cut surfaces indicate both the energy attenuation and the development of radial velocity components in the jet stream. When the sample is positioned with different distances from the nozzle outlet, the obtained quantitative surface roughness varies accordingly. A descriptive model highlighting the behaviors of abrasive particles in jet-cutting process is established in light of the experimental results and correlation analysis.

  14. Public Notice: Saint-Gobain Abrasives, Inc. and Saint-Gobain Ceramics & Plastics, Inc., CWA-01-2016-0057

    Notice of Proposed Assessment of Class II Civil Penalty and Notice of Opportunity for Hearing under Sections 309(g) and 311(b)(6) of the Clean Water Act for Saint-Gobain Abrasives, Inc. and Saint-Gobain Ceramics & Plastics, Inc., CWA-01-2016-0057

  15. Lung scintigraphy evaluation in workers exposed to abrasive dusts; Avaliacao cintilografica pulmonar em trabalhadores de industria de abrasivos

    Terra Filho, Mario


    The production process of abrasives use aluminium, or silicon carbide a synthetic material with a hardness only slightly less than that of a diamond. It is popularly known as carborundum since it was first manufactured as an abrasive in 1891, produced by the fusion of high grade silica and petroleum coke with sawdust. For many years silicon carbide was thought not to give rise to pulmonary lesions. Recently several researchers suggested the existence of a carborundum pneumoconiosis. The aim of this study was to evaluate the role of the pulmonary clearance of {sup 99m} Technetium chelated to diethylene-triamine penta-acetate ({sup 99m} Tc DTPA), and {sup 67} Gallium lung scanning in workers exposed to abrasive dusts. Thirty seven subjects, 13 smokers and 24 nonsmokers and ex smokers were studied. In 32 (86,48%) {sup 67} Gallium lung scanning was positive including 13 (40,62%) retired workers. We conclude that non smoking workers of abrasives plants have a pulmonary alveolar epithelial permeability disturbance similar as observed in smoking workers and smoking controls. Most workers, ex-workers of these industries and in patients with carborundum pneumoconiosis there is an evidence of pulmonary inflammation measured with abnormal {sup 67} Gallium lung scan. (author) 101 refs., 2 figs., 11 tabs.

  16. Fissure sealants: in vitro evaluation of abrasion wear and superficial roughness

    Vanessa Pardi


    Full Text Available The aim of this study was to compare the in vitro wear and superficial roughness of four materials (Delton Dyract Flow, Dentsply; Filtek Flow, Vitremer, 3M ESPE used as fissure sealant in 32 extracted human molars divided in four groups (n = 8 after abrasion with toothbrush/dentifrice. Impressions of each occlusal surface were made to analyze wear and circular specimens were prepared to analyze the roughness. Teeth and specimens were mounted in a toothbrushing machine. The replicas were observed using a SEM to determine the superficial wear. Wear: there were no statistically significant differences either between Delton and Filtek Flow or between Dyract Flow and Vitremer. Roughness: there were no statistical differences between Filtek Flow and Dyract Flow, Dyract Flow and Vitremer, Vitremer and Delton., Considering the clinical practice, if caries activity is present the use of Vitremer is suggested not only for its well known fluoride release, but it presented good roughness results.

  17. Microstructure and Abrasive Mechanism of Surfacing Welding Based on TiC-VC Particle

    YANGShang-lei; LUXue-qin; ZOUZeng-da; LOUSong-nian


    Ultrahard titanium and vanadium carbides (TiC-VC) particles are combined among ferrotitanium (Fe-Ti), ferrovanadium (Pe-V), graphite, ruffle, etc. by means of high temperature arc metallurgic reaction in deposited metal. The mierostructure, properties and wear mechanism of surfacing metal were systemically studied. The results show carbides particles are embedded in Fe matrix, Microstructure of which is lath martensite. The carbides mixed in the lath martensite provide a combination of good hardness and toughness. The residual austenite transforms to martensite, which is caused by the press stress, strengthens the matrix and releases the stress. The surface layers have high abrasive resistance and cracking resistance. The integration of dispersedly distributed carbides, lath martensite and residual austenite of the surface layer results in satisfactory wear resistance.

  18. Microstructure and Abrasive Mechanism of Surfacing Welding Based on TiC-VC Particle

    YANG Shang-lei; LU Xue-qin; ZOU Zeng-da; LOU Song-nian


    Ultrahard titanium and vanadium carbides (TiC-VC) particles are combined among ferrotitanium (Fe-Ti),ferrovanadium (Fe-V), graphite, rutile, etc. by means of high temperature arc metallurgic reaction in deposited metal. The microstructure, properties and wear mechanism of surfacing metal were systemically studied. The results show carbides particles are embedded in Fe matrix, Microstructure of which is lath martensite. The carbides mixed in the lath martensite provide a combination of good hardness and toughness. The residual austenite transforms to martensite, which is caused by the press stress, strengthens the matrix and releases the stress. The surface layers have high abrasive resistance and cracking resistance. The integration of dispersedly distributed carbides, lath martensite and residual austenite of the surface layer results in satisfactory wear resistance.

  19. Abrasive resistance of arc sprayed carbonitride alloying self-shielded coatings

    Deng, Yu; Yu, Shengfu; Xing, Shule; Huang, Linbing; Lu, Yan


    Wear-resistant coatings were prepared on the surface of the Q235 low-carbon steel plate by HVAS with the carbonitride alloying self-shielded flux-cored wire. Detection and analysis on the microstructure and properties of the coatings were carried out by using scanning electron microscope, microhardness tester and wear tester. The forming, the wear resistance and its mechanism of the coatings were studied. The results show that the coatings have good forming, homogeneous microstructure and compact structure. The coatings have good hardness, the average microhardness value reaches 520 HV 0.1, and the highest value is up to about 560 HV 0.1. As a result, the coatings have good abrasive wear performance and adhesion strength.

  20. Surface topography of cylindrical gear wheels after smoothing in abrasive mass, honing and shot peening

    Michalski, J; Pawlus, P [Rzeszow University of Technology, W Pola 2, 35-935 Rzeszow (Poland); Zelasko, W, E-mail: [Technical School Complex at Lezajsk, Mickiewicza 67, 37-300 Lezajsk (Poland)


    The present paper presents the analysis of surface topography of gear teeth as the result of final machining processes. Teeth of multiple cylindrical gears shaped by grinding were smoothed in abrasive mass, honed or shot peened. The measurement of gears were made using coordinate measuring machine and 3D surface topography stylus instrument. The following deviations were studied; pitch deviation, total pitches deviations, variation of teeth thickness and deviation of gear radial run-out. Changes in teeth surface topography during machining process were determined. 3D surface topography parameters, surface directionality as well as areal autocorrelation and power spectral density functions were taken into consideration. As the results of the analysis, the best surface topography with regard to gear operational properties was recommended.

  1. Surface topography of cylindrical gear wheels after smoothing in abrasive mass, honing and shot peening

    Michalski, J.; Pawlus, P.; Żelasko, W.


    The present paper presents the analysis of surface topography of gear teeth as the result of final machining processes. Teeth of multiple cylindrical gears shaped by grinding were smoothed in abrasive mass, honed or shot peened. The measurement of gears were made using coordinate measuring machine and 3D surface topography stylus instrument. The following deviations were studied; pitch deviation, total pitches deviations, variation of teeth thickness and deviation of gear radial run-out. Changes in teeth surface topography during machining process were determined. 3D surface topography parameters, surface directionality as well as areal autocorrelation and power spectral density functions were taken into consideration. As the results of the analysis, the best surface topography with regard to gear operational properties was recommended.

  2. Analog Studies of Thermomechanical Fatigue and Abrasive Wear of Cast and Forged Steels for "Autoforge" Dies

    Kolesnikov, M. S.; Mironova, Yu. S.; Mukhametzyanova, G. F.; Novikova, I. E.; Novikov, V. Yu.


    Processes of thermomechanical fatigue and abrasive wear of suspension-cast precipitation-hardening ferrite-carbide steel 30T6NTiC-1.5 and standard steel 4Kh5MFS are studied. The dominant kinds of fracture typical for dies for semisolid stamping are determined. The factors and parameters of cyclic temperature and force loading are shown to produce a selective action on the competing kinds of damage of the die steels. A comparative analysis of the properties of the steels is performed. Steel 30T6NTiC-1.5 is shown to have substantial advantages over steel 4Kh5FMS traditionally used for making "Autoforge" dies.

  3. Impact strength and abrasion resistance of high strength concrete with rice husk ash and rubber tires

    M. B. Barbosa

    Full Text Available The paper discusses the application of High Strength Concrete (HSC technology for concrete production with the incorporation of Rice Husk Ash (RHA residues by replacing a bulk of the material caking and rubber tires with partial aggregate volume, assessing their influence on the mechanical properties and durability. For concrete with RHA and rubber, it was possible to reduce the brittleness by increasing the energy absorbing capacity. With respect to abrasion, the RHA and rubber concretes showed lower mass loss than the concrete without residues, indicating that this material is attractive to be used in paving. It is thus hoped that these residues may represent a technological and ecological alternative for the production of concrete in construction works.

  4. An acoustic emission study of cutting bauxite refractory ceramics by abrasive water jets

    Momber, A. W.; Mohan, R. S.; Kovacevic, R.


    This article discusses the material removal process in bauxite refractory ceramics cut by abrasive water jets. Several parameters of the process were changed during the experiments. The experiments were monitored online by the acoustic emission (AE) technique. It was found that AE signals are able to sense the material removal process as well as the machining performances very reliably. Unsteady material removal mode consisting of matrix removal and intergranular fracture was very well represented in the AE signals by an unsteady time dependent signal type characterized by burst emissions and a frequency domain signal associated with a twin-peak shape. The particular characteristics of the signal depend on the energy involved in the process.

  5. Corneal abrasion and alkali burn secondary to automobile air bag inflation

    Scarlett, Angela; Gee, Paul


    A 59‐year‐old woman self presented to the emergency department with a painful right eye following a motor vehicle accident. She had reduced visual acuity and the eye had an alkaline pH with complete corneal uptake of fluorescein. Diagnosis of corneal abrasion and alkali burn to her right eye secondary to inflation of a driver's automobile airbag was made. The eye was irrigated with normal saline. Such injuries, although rare, can easily be identified within the emergency department by the history of exposure, evidence of facial injuries or burns, and an alkaline pH in the inferior cul‐de‐sac of the eye. Early detection and management with ophthalmology review is therefore imperative to prevent irreversible visual impairment. PMID:17901284

  6. Magnetic force improvement and parameter optimization for magnetic abrasive polishing of AZ31 magnesium alloy


    The magnetic force acting on workpieee to be machined plays a significantly important role in magnetic abrasive polishing process.But in a case of polishing nonferrous materials,the strength of magnetic force is very low and it leads lower polishing efficiency.The magnesium alloy that has superior mechanical properties for industrial application such as a lightweight and high specific strength is one of the most famous nonferrous materials.An improving strategy of the magnetic force for me AZ31 magnesium alloy installed with a permanent magnet was proposed and experimental verification Was carded out.For the proposed strategy,the effect of process parameters on the surface roughness of the AZ31 magnesium alloy Was evaluated by a design of experimental method.

  7. Multi-objective optimization of circular magnetic abrasive polishing of SUS304 and Cu materials

    Nguyen, NhatTan; Yin, ShaoHui; Chen, FengJun; Yin, HanFeng [Hunan University, Changsha (China); Pham, VanThoan [Hanoi University, Hanoi (Viet Nam); Tran, TrongNhan [Industrial University of Ho Chi Minh City, HCM City (Viet Nam)


    In this paper, a Multi-objective particle swarm optimization algorithm (MOPSOA) is applied to optimize surface roughness of workpiece after circular magnetic abrasive polishing. The most important parameters of polishing model, namely current, gap between pole and workpiece, spindle speed and polishing time, were considered in this approach. The objective functions of the MOPSOA depend on the quality of surface roughness of polishing materials with both simultaneous surfaces (Ra1, Ra2), which are determined by means of experimental approach with the aid of circular magnetic field. Finally, the effectiveness of the approach is compared between the optimal results with the experimental data. The results show that the new proposed polishing optimization method is more feasible.

  8. Comparative Investigation on Brazing Behavior, Compressive Strength, and Wear Properties of Multicrystalline CBN Abrasive Grains

    Wen-Feng Ding


    Full Text Available In order to fabricate the abrasive wheels with good grain self-sharpening capacity, two types of multicrystalline CBN grains, that is, polycrystalline CBN (PCBN and binderless CBN (BCBN, were brazed using Cu-Sn-Ti alloy, respectively. Comparative investigation on the brazing interface, compressive strength, and wear properties of the different grains was carried out. Results obtained show that the PCBN grains have more intricate reaction, more complicated resultants, and thicker reaction layer than the BCBN counterparts under the identical brazing conditions. Though the average compressive strength of the PCBN grains is similar to that of BCBN ones, stronger self-sharpening action by virtue of the microfracture behavior takes place with BCBN grains during grinding. As a consequence, compared to the brazed PCBN wheels and the conventional monocrystalline CBN (MCBN ones, longer service life is obtained for the brazed BCBN wheels.

  9. Experimental research on the machinability of Hardox steel by abrasive waterjet cutting

    Filip Alexandru Catalin


    Full Text Available One of the main present industry challenges is finding the most efficient manufacturing process for a certain part. When parts are made of strong steels like Hardox, their fabrication method is usually difficult. Abrasive waterjet cutting (AWJ is one of the cutting processes which can be used in this case. This paper presents an experimental research on the machinability of Hardox steel by AWJ. The experiments were conducted using a factorial design model considering two of the main influence parameters like the traverse speed and the distance between the nozzle and the surface of the material. Based on the measurement of the dimensions and the roughness of the parts, the influence of the parameters was revealed and analyzed. The manufacturing time was also compared, as it directly influences the production cost. Further research is considered to develop a mathematical model which can be used for a proper choice of the process parameters depending on the initial requirements.

  10. The role of the microfissuration of the rock matrix in the abrasion resistance of ornamental granitic rocks

    Rodríguez-Rey, Angel; Sanchez-Delgado, Nuria; Camino, Clara; Calleja, Lope; Ruiz de Argandoña, Vicente G.; Setien, Alexia


    The microcrack density and the abrasion resistance of five ornamental granites (Albero, Gris Alba, Mondariz, Rosa Porriño and Traspieles) from Galicia (NW Spain) have been quantified as part of a research aimed to interpret the cuttability of the rocks in relation to the petrophysical properties of the rock matrix. Large blocks from the quarries have been cut with an industrial saw and the microcrack density and the abrasion resistance have been measured in two surfaces: H, parallel to the cut surface; T, perpendicular both to the cut surface and the cutting direction. Both planes are perpendicular to the rift plane, as it is known in quarry works. The microcrack density has been quantified following an stereological procedure applied to polished sections imaged under scanning electron microscopy. The magnification of the images allowed the study of microcracks as narrow as 2 microns in aperture. The density has been quantified in terms of length of microcrack traces per surface unit so possible anisotropies of the microcrack network could be detected. The obtained values are in the typical range for this type of rocks although the Traspieles granite shows a higher value due to its weathering degree (H: 5.11, T: 5.37 mm/mm2). The values measured in the two surfaces (H and T) are quite similar in four of the rocks; only the Albero granite shows a marked anisotropy (H: 2.76 T: 3.53 mm/mm2). The abrasion resistance of the rocks has been measured following the european standard EN 14157:2004 using the capon method. The rocks can be classified in two groups according to their abrasion resistance. Rosa Porriño, Gris Alba and Mondariz granites are the more resistant to abrasion with values around 16-17 mm. Albero and Traspieles granites are less resistant with values higher than 19 mm. The results show a good correlation between the microcrack density and the abrasion resistance. As can be expected the rocks with high microcrack density show low abrasion resistance. The

  11. Conventional and anti-erosion fluoride toothpastes: effect on enamel erosion and erosion-abrasion.

    Ganss, C; Lussi, A; Grunau, O; Klimek, J; Schlueter, N


    New toothpastes with anti-erosion claims are marketed, but little is known about their effectiveness. This study investigates these products in comparison with various conventional NaF toothpastes and tin-containing products with respect to their erosion protection/abrasion prevention properties. In experiment 1, samples were demineralised (10 days, 6 × 2 min/day; citric acid, pH 2.4), exposed to toothpaste slurries (2 × 2 min/day) and intermittently stored in a mineral salt solution. In experiment 2, samples were additionally brushed for 15 s during the slurry immersion time. Study products were 8 conventional NaF toothpastes (1,400-1,490 ppm F), 4 formulations with anti-erosion claims (2 F toothpastes: NaF + KNO(3) and NaF + hydroxyapatite; and 2 F-free toothpastes: zinc-carbonate-hydroxyapatite, and chitosan) and 2 Sn-containing products (toothpaste: 3,436 ppm Sn, 1,450 ppm F as SnF(2)/NaF; gel: 970 ppm F, 3,030 ppm Sn as SnF(2)). A mouth rinse (500 ppm F as AmF/NaF, 800 ppm Sn as SnCl(2)) was the positive control. Tissue loss was quantified profilometrically. In experiment 1, most NaF toothpastes and 1 F-free formulation reduced tissue loss significantly (between 19 and 42%); the Sn-containing formulations were the most effective (toothpaste and gel 55 and 78% reduction, respectively). In experiment 2, only 4 NaF toothpastes revealed significant effects compared to the F-free control (reduction between 29 and 37%); the F-free special preparations and the Sn toothpaste had no significant effect. The Sn gel (reduction 75%) revealed the best result. Conventional NaF toothpastes reduced the erosive tissue loss, but had limited efficacy regarding the prevention of brushing abrasion. The special formulations were not superior, or were even less effective.

  12. 磨料水射流对硬质合金切割深度的试验研究%Experimental study on cutting depth of hard alloy by abrasive water jet

    宋金来; 关砚聪; 赵宏伟; 孙艳斌


    通过用高压磨料水射流对硬质合金进行切割,以单因素试验的形式分析了射流压力、切割速度、磨料流量、靶距对硬质合金材料切割深度的影响。在单因素试验的基础上,选定各因素的水平进行正交试验,通过极差分析对加工参数进行优化。结果表明:各因素对切割深度的影响主次关系依次为射流压力、切割速度、磨料流量、靶距;获得最大切割深度的最优工艺参数为:射流压力280 MPa、切割速度50.8 mm/min、磨料流量545 g/min、靶距5 mm,此时实测切割深度为0.70 cm,达到最佳效果。%By cutting experiments of hard alloy using high pressure abrasive water-jet,the influences of jet pressure,cutting speed,abrasive flow rate and target distance on the cutting depth are analyzed using single factor method.Based on the single factor tests,the levels of these factors are selected for orthogonal test,and the processing parameters are optimized by range analysis.The results show that the influence of factors on the cutting depth ranks as following:jet pressure>cutting speed>abrasive flow>target distance.And the optimal processing parameters are jet pressure 280 MPa,cutting speed 50.8 mm∕min,abrasive flow rate 545 g∕min,target distance 5 mm.The cutting depth can reach the best under the optimal parameters,which is 0.70 cm.

  13. Abrasive selection of honing stone for TC11 titanium alloy hole honing%钛合金TC11深孔珩磨时油石磨料的选择

    刘雁蜀; 彭海


    深孔珩磨钛合金难度很大.本研究针对TC11的特性,选用不同主磨料和辅磨料,按不同混合比例研制了15种珩磨油石,并用它们对TC11钛合金进行深孔珩磨对比试验.利用动态电阻应变仪、函数记录仪和测扭矩传感器进行了数据跟踪,绘制出了各混合磨料油石珩磨钛合金的磨削比和比磨削能图.结合示图分析,最终确定珩磨TC11的油石材料应选用GC70%+SA30%的混合磨料油石.这种混合磨料油石表现为珩磨去除量大,粘附少,磨削质量好.%Deep hole honing on Ti alloy TC - 11 is quite a difficult job. Based on the characteristics of TC -11, the authors selected different abrasive grits as principle and auxiliary abrasive and, with different proportion design, prepared 15 oil stone samples. Honing tests were carried out using dynamic resistance strain tester, X - Y plotter and torque sensor for date acquisition and processing. Diagrams of specific energy and grinding ratio of the honing stone samples were drawn and analyzed. The results showed that , the hybrid abrasive honing stone with GC (70% ) and SA ( 30% ) performed the highest removal rate , few load and the best honing quality .

  14. Infrared diagnosis of contact wire abrasion based on surface temperature method%基于表面温度法的接触线磨耗红外诊断

    阎玲玲; 金立军; 张文豪; 杨政勃


    为解决接触网接触线磨耗检测问题,将红外技术应用到接触线磨耗检测中.开展了接触线磨耗缺陷处温升分析,建立了接触线的表面温度与其横截面积之间的关系,提出了利用接触线缺陷处温度计算横截面积的方法,在测量误差上对接触线磨耗的判断方法进行了评价,在实验室模拟了接触线温升的试验.研究结果表明,利用表面温度法对接触线磨耗的测量误差不超过10%,证明了该方法的可用性.%In order to solve the problems of defect of contact wire abrasion,the infrared technique was investigated. After the analysis of the surface temperature of the defect, the relationship of the surface temperature and its cross-sectional area was established. A method was presented to calculate the cross-sectional area of contact wire abrasion with the temperature of the surface. The judgment of contact wire abrasion was evaluated by the index of measurement error,the temperature rises of contact wire were tested in the laboratory. The experimental results show that the maximum measurement error is less than 10%, so the method proposed is practicable.

  15. Effect of Phenomena Accompanying Wear in Dry Corundum Abrasive on the Properties and Microstructure of Austempered Ductile Iron with Different Chemical Composition

    Myszka D.


    Full Text Available The research described in this article is a fragment in the series of published works trying to determine the applicability of new materials for parts of the mining machinery. Tests were performed on two groups of austempered ductile iron - one of which contained 1.5% Ni and 0.5% Mo, while the other contained 1.9% Ni and 0.9% Cu. Each group has been heat treated according to the three different heat treatment variants and then the material was subjected to detailed testing of mechanical properties and abrasion wear resistance, measuring also hardness and magnetic properties, and conducting microstructural examinations. The results indicated that each of the tested materials was senstive to the surface hardening effect, which resulted in high wear resistance. It has been found that high temperature of austempering, i.e. 370°C, favours high wear resistance of ductile iron containing nickel and molybdenum. Low temperature of austempering, i.e. 270°C, develops high wear resistance in ductile iron containing nickel and copper. Both these materials offer completely different mechanical properties and as such can be used for different and specific applications.

  16. Effect of Fe content on the friction and abrasion properties of copper base overlay on steel substrate by TIG welding

    Lü Shixiong; Song Jianling; Liu Lei; Yang Shiqin


    Copper base alloy was overlaid onto 35CrMnSiA steel plate by tungsten inert gas (TIG) welding method. The heat transfer process was simulated, the microstructures of the copper base overlay were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), and the friction and abrasion properties of the overlay were measured. The results show that the Fe content increases in the overlay with increasing the welding current. And with the increase of Fe content in the overlay, the friction coefficient increases and the wear mechanism changes from oxidation wear to abrasive wear and plough wear, which is related to the size and quantity of Fe grains in the overlay. While with the increase of Fe content in the overlay, the protection of oxidation layer against the oxidation wear on the melted metal decreases.

  17. Characterization of colloidal silica abrasives with different sizes and their chemical–mechanical polishing performance on 4H-SiC (0 0 0 1)

    Shi, Xiaolei [The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Pan, Guoshun, E-mail: [The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Zhou, Yan; Gu, Zhonghua; Gong, Hua; Zou, Chunli [The State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)


    In this paper, a detailed analysis is presented to characterize the performance of colloidal silica abrasives based slurry with different abrasive sizes on CMP of hexagonal 4H-SiC wafer, and indicates that the abrasive size is an important factor to determine the efficiency of CMP and the final planarization quality of wafer surface. The authors also present a detailed hypothesis to describe the material removal mechanism of 4H-SiC by colloidal silica abrasives during CMP process, and design two groups of experiments to demonstrate the rationality of the hypothesis. Furthermore, the authors put forward some suggestions to optimize the CMP efficiency and planarization quality of 4H-SiC wafer.

  18. Interactions between severe environment and concrete resistance to abrasion and erosion%混凝土磨蚀冲蚀与其它环境因素的耦合作用



    Concrete becomes more and more invulnerable to abrasion/erosion degradation upon severe envi⁃ronmental exposure, especially when the service condition is coupled with chloride salt penetration, sulfate attack,and freezing-thawing cycles,etc. This degradation leads to repeated maintenance or service interrup⁃tion to significant hydraulic and marine infrastructure, resulting in tremendous economic losses. Starting from environmental influence and engineering service characteristics, this paper discusses the concrete resis⁃tance to abrasion-erosion degradation and failure modes under different service conditions. The testing meth⁃ods for concrete resistance to abrasion/erosion, and the microstructural control mechanism are evaluated, and the recommendations for development of high performance concrete for abrasion/erosion resistance appli⁃cations are proposed.%日趋严酷的服役环境使得混凝土磨蚀冲蚀与其它环境因素(氯盐侵蚀、硫酸盐侵蚀、冻融循环等)联合作用的问题愈来愈突出,其后果是导致重要水工、海工混凝土结构反复维修甚至过早失稳破坏,造成严重的经济损失。本文从环境因素和工程服役特性出发,对混凝土在不同工况条件下磨蚀冲蚀类型、破坏机理、评价方法、微结构调控机制等方面进行了阐述,指出需更加重视磨蚀冲蚀与其他环境因素联合作用下混泥土耐久性的研究,为高性能抗冲耐磨混凝土的研究与设计提出了建议。

  19. Research on High Pressure Abrasive Water Jet Nozzle,an Offshore Clean Cutting Core Technology%海上清洁切割核心技术--高压磨料射流切割喷嘴研究

    马认琦; 鞠少栋; 王超


    In order to realize the safety and high efficiency of cutting and recovery operations for abandoned offshore pro-duction facilities to guarantee the implementation of Maritime Silk Road Strategy and the expansion of CNOOC’s offshore clean and environmental friendly cutting technical services, a high pressure abrasive water jet cutting nozzle was designed and optimized through theoretical research and experimental tests, which can be used for available abrasive water jet tech-nology. Its key techniques include abrasive acceleration in the nozzle, optimization of nozzle structure, design of inner flow path, material and sintering process selection. The nanometer anti-abrasive nozzles were developed and field cutting opera-tions have been completed. This achievement has improved the operating efficiency and service level for abandoned CNOOC offshore production facilities.%为实现海上废弃结构物的安全高效切割回收,保障海上丝绸之路战略构想的顺利实施,同时做大做强中海油海上清洁环保切割技术服务产业,针对公司现有的磨料射流切割技术,通过理论研究与试验测试的方法,设计并自主研制高压磨料射流切割喷嘴,重点解决了喷嘴内部磨料加速受力研究、喷嘴结构型式优选及内部流道设计、喷嘴选材及烧结工艺优选等关键技术。最终,研发出高性能纳米级耐磨喷嘴并成功完成了现场切割应用,该成果显著提高了中海油海上结构物弃置作业效率和整体技术服务水平。

  20. 前混式磨料射流发生系统混合腔的优化设计%Optimization Design of Mixing Chamber of the Pre-mixed Abrasive Water Jet Generating System

    王方祥; 王瑞和; 周卫东; 李罗鹏; 王明波; 仲冠宇


    The mixing chamber is an important part of the pre-mixed abrasive water jet generating sys-tem. Appropriate mixing chamber structure is benefit for the mixing of abrasive material and water to improve the u-tilization of hydro energy. Considering the interaction between the liquid and solid phase, the standard κ-ε turbu-lence model is applied to simulate the two-phase flow in the mixing chamber. Based on the nonuniformity of the mix-ing, statistical method was used to optimize the main structure parameters of the mixing chamber so that to attain optimized structure dimensions, test the abrasive material volume fraction and casing cutting. The study results show that the abrasive material volume fraction fluctuates around the calibration value within a narrow range after the optimization. The casing cutting efficiency is significantly improved and the cutting edge of casing is smoother, indicating an improved liquid-solid mixing performance of the optimized mixing chamber.%混合腔是前混式磨料射流发生系统的核心部件, 合理的混合腔结构参数有利于磨料和水的混合, 从而提高水力能量利用率. 考虑液固两相的相互作用, 采用标准κ-ε双方程模型, 对混合腔内液固两相流场进行数值模拟研究, 以液固混合不均匀度为标准, 利用统计学方法对混合腔主要结构参数进行优化设计, 获得最优结构尺寸组合, 并进行磨料体积分数测试试验及套管切割试验. 研究结果表明, 优化后磨料体积分数与标定值相比波动明显减小, 磨料射流切割套管的效率明显提高, 且套管断面更加光滑整齐, 说明优化后的混合腔能够显著提高液固混合均匀程度.

  1. A new eye gel containing sodium hyaluronate and xanthan gum for the management of post-traumatic corneal abrasions

    Faraldi F


    Full Text Available Francesco Faraldi,1 Vincenzo Papa,2 Debora Santoro,2 Daria Rasà,2 Annamaria L Mazza,2 Maria M Rabbione,1 Simona Russo21Department of Ophthalmology III, Presidio Ospedaliero Oftalmico, Torino, Italy; 2SIFI SpA, Catania, ItalyPurpose: The aim of this study was to investigate the effects of an ophthalmic gel containing sodium hyaluronate and xanthan gum in addition to the antibiotic netilmicin in the management of traumatic corneal abrasions.Patients and methods: Patients with traumatic corneal abrasions were randomly treated as follows: Group A (n = 20 with an occlusive patching for 12 hours plus one drop of an eye gel containing 0.15% sodium hyaluronate, 1% xanthan gum and 0.3% netilmicin qid for 5 days; and Group B (n = 20 with an occlusive patching for 2–3 days plus one application of 0.3% netilmicin ophthalmic ointment qid for 5 days. All patients were evaluated after the third and seventh day by slit-lamp examination, fluorescein staining, and corneal defect photograph in order to assess corneal re-epithelialization. Conjunctival hyperaemia, lid oedema, subjective symptoms of discomfort, and conjunctival swabs were also evaluated.Results: No statistically significant difference was observed between the groups in terms of the extent of corneal healing after 3 days of treatment. Both treatments were also highly effective in decreasing the erosion score and the conjunctival hyperemia (P < 0.0001, P < 0.005, respectively without any significant difference between the two types of treatment. Subjective symptoms of discomfort and conjunctival swabs were also evaluated.Conclusion: In the management of traumatic corneal abrasions, the administration of an eye gel containing sodium hyaluronate and xanthan gum is able to reduce the length of occlusive patching. In addition, the presence of netilmicin guarantees good antibiotic prophylaxis during the wound repair process.Keywords: netilmicin, xanthan gum, wound healing, patching, corneal abrasion

  2. The Cutting Front Side Geometry in The Applications of D3 Cold Work Tool Steel Material Via Abrasive Water Jet

    Adnan AKKURT


    Abrasive water jet cutting that is used as cold cutting technology in industrial applications is preferred as most productive method when especially metallurgic and mechanic specialties of materials are taken into consideration. When the surface quality, speed of processing period and part cost are taken into consideration, which are targeted in D3 cold work tool steel materials used frequently in especially metal industry, it appears that the most appropriate method is ab...

  3. The possible use of Bayer process cyclone fines for manufacture of abrasives

    Sancho, J.


    Full Text Available This paper deals with the feasibihty of producing synthetic abrasives from a by-product of the Bayer process: the cyclone fines, through synthesis aided by mineralizers addition. The main result has been the production of a low temperature (1200-1300 °C polish by adding fluoride mineralizers, that could be in clear competence with synthetic corundum obtained also in this work by a more traditional way: sodium removal, using of magnesium oxide as mineralizer, and high calcination temperatures (1700 °C.

    En este trabajo se demuestra la posibilidad de producir abrasivos a partir de un subproducto de la fabricación de la alúmina Bayer: los finos de ciclón, mediante la síntesis ayudada por la adición de mineralizantes. Un resultado importante ha sido la obtención de un pulimento a baja temperatura, (1.200-1.300 °C mediante mineralizantes fluorados, que puede competir de forma clara con corindones sintéticos obtenidos, también en este trabajo, de forma tradicional: eliminación de sodio, utilización de óxido de magnesio como mineralizante y elevadas temperaturas de calcinación (1.700 °C.

  4. Abrasive wear behaviors of high velocity arc sprayed iron aluminum composite coatings

    Weipu Xu; Binshi Xu; Wei Zhang; Zixin Zhu; Yixiong Wu


    The High Velocity Arc Spraying (HVAS) technology was used to prepare Fe-Al composite coatings by the adding of different elements into cored wires to obtain different Fe-Al coatings. The added compounds do great effect on the properties of the composite coatings. The microstructures and abrasive wear performances of the coatings were assessed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and THT07-135 high temperature wear equipment. It was found that the adding of Cr3C2 can greatly increase the room temperature wear behavior, and Fe-Al/WC coatings have adapting periods at the beginning of wear experiment. With the rise of temperature, the wear resistance of Fe-Al/Cr3C2 coatings becomes bad from room temperature to 250℃, and then stable from 250℃ to 550℃; the wear resistance of Fe-Al/WC becomes well with the rise of temperature.The adding of Cr and Ni can also improve wear performances of Fe-Al composite coatings.

  5. Profilometric analysis of two composite resins′ surface repolished after tooth brush abrasion with three polishing systems

    Mudit Uppal


    Full Text Available Aim: To evaluate the effect of three polishing protocols that could be implemented at recall on the surface roughness of two direct esthetic restorative materials. Materials and Methods: Specimens (n = 40 measuring 8 mm (length × 5 mm (width × 4 mm (height were fabricated in an acrylic mold using two light-cured resin-based materials (microfilled composite and microhybrid composite. After photopolymerization, all specimens were finished and polished with one of three polishing protocols (Enhance, One Gloss, and Sof-Lex polishing systems. The average surface roughness of each treated specimen was determined using 3D optical profilometer. Next all specimens were brushed 60,000 times with nylon bristles at 7200 rpm using crosshead brushing device with equal parts of toothpaste and water used as abrasive medium. The surface roughness of each specimen was measured after brushing followed by repolishing with one of three polishing protocols, and then, the final surface roughness values were determined. Results: The data were analyzed using one-way and two-factor analysis of variance (ANOVA and Tukey′s honestly significant difference (HSD. Significant difference (P < 0.05 in surface roughness was observed. Simulated brushing following initial polishing procedure significantly roughened the surface of restorative material (P < 0.05. Conclusion: Polishing protocols can be used to restore a smooth surface on esthetic restorative materials following simulated tooth brushing.

  6. Characterization of nanoparticles from abrasive waterjet machining and electrical discharge machining processes.

    Ling, Tsz Yan; Pui, David Y H


    Abrasive Waterjet Machining (AWM) and Electrical Discharge Machining (EDM) processes are found to produce nanoparticles during operation. Impacts of engineered nanoparticles released to the environment and biological system have caused much concern. Similarly, the nanoparticles unintentionally produced by the AWM and EDM can lead to comparable effects. By application of the Nanoparticle Tracking Analysis (NTA) technique, the size distribution and concentration of nanoparticles in the water used in AWM and EDM were measured. The particles generally have a peak size of 100-200 nm. The filtration systems of the AWM and EDM processes were found to remove 70% and 90% the nanoparticles present, respectively. However, the particle concentration of the filtered water from the AWM was still four times higher than that found in regular tap water. These nanoparticles are mostly agglomerated, according to the microscopy analysis. Using the electron dispersive spectroscopy (EDS) technique, the particles are confirmed to come from the debris of the materials cut with the equipment. Since AWM and EDM are widely used, the handling and disposal of used filters collected with nanoparticles, release of nanoparticles to the sewer, and potential use of higher performance filters for these processes will deserve further consideration.

  7. Sandblasting as a surface modification technique on titanium alloys for biomedical applications: abrasive particle behavior

    Balza, J. C.; Zujur, D.; Gil, L.; Subero, R.; Dominguez, E.; Delvasto, P.; Alvarez, J.


    The present work shows the analysis of a sandblasting process using alumina abrasive particles on Ti-6Al-4V surfaces. The metallic samples were first characterized by optical microscopy (OM), revealing an α+β microstructure with a Widmanstätten morphology. Topography of the samples was assessed by scanning electron microscopy (SEM), before and after sandblasting. The Al2O3 particles used had a granulometric distribution between 420 and 850 μm, with a median particle size (d50) of 670 μm, which decreased to 420 μm after sandblasting for 10 seconds. This change in the size of the particles generated a loss on particle kinetic energy by a factor of 3.5. Such variation on processing conditions induced a progressive increase on average roughness (Ra) of the Ti-6Al-4V surfaces, until the first 7 seconds were reached. From that point on, a reverse process was observed, exerting a polishing effect on the surface of the Ti-6Al-4V alloy.

  8. Toothpastes containing abrasive and chemical whitening agents: efficacy in reducing extrinsic dental staining.

    Soares, Cristina Neves Girao Salgado; Amaral, Flavia Lucisano Botelho do; Mesquita, Marcelo Ferraz; Franca, Fabiana Mantovani Gomes; Basting, Roberta Tarkany; Turssi, Cecilia Pedroso


    This in vitro study evaluated the efficacy of toothpastes containing abrasive and chemical whitening agents in reducing the extrinsic discoloration of dental enamel. Sixty slabs of dentin from human teeth were sealed so that only the enamel surface was exposed. The enamel surfaces were photographed for initial color assessment. Staining was performed by immersing the dental slabs in 0.2% chlorhexidine solution for 2 minutes and then in black tea for 60 minutes. This process was repeated 15 times. Photographs were taken at the end of the staining process, and the slabs were divided into 5 groups (n = 12), 3 to be brushed with toothpastes containing chemical whitening agents (2 containing phosphate salts and 1 containing phosphate salts plus hydrogen peroxide) and 2 to represent control groups (ordinary/nonwhitening toothpaste and distilled water). The dental slabs were subjected to mechanical toothbrushing with toothpaste slurry or distilled water, according to each group's specifications. After brushing, more photographs were taken for color analysis. The results showed a significant reduction in luminosity after the staining process in addition to an increase in the colors red and yellow (P toothpastes and the changes found in slabs brushed with ordinary toothpaste. The whitening toothpastes did not outperform an ordinary toothpaste in the removal of extrinsic staining.

  9. Uniform surface polished method of complex holes in abrasive flow machining

    A-Cheng WANG; Lung TSAI; Kuo-Zoo LIANG; Chun-Ho LIU; Shi-Hong WENG


    Abrasive flow machining(AFM) is an effective method that can remove the recasting layer produced by wire electrical discharge machining(WEDM). However, the surface roughness will not be easily uniform when a complex hole is polished by this method. CFD numerical method is aided to design good passageways to find the smooth roughness on the complex hole in AFM. Through the present method, it reveals that the shear forces in the polishing process and the flow properties of the medium in AFM play the roles in controlling the roughness on the entire surface. A power law model was firstly set up by utilizing the effect of shear rates on the medium viscosities, and the coefficients of the power law would be found by solving the algebraic equation from the relations between the shear rates and viscosities. Then the velocities, strain rates and shear forces of the medium acting on the surface would be obtained in the constant pressure by CFD software. Finally, the optimal mold core put into the complex hole could be designed after these simulations. The results show that the shear forces and strain rates change sharply on the entire surface if no mold core is inserted into the complex hole, whereas they hardly make any difference when the core shape is similar to the complex hole. Three experimental types of mold core were used. The results demonstrate that the similar shape of the mold core inserted into the hole could find the uniform roughness on the surface.

  10. Experimental study of free abrasive wire sawing by using multi-strands wire

    Yao Chunyan; Wang Jinsheng; Peng Wei; Jin Xin; Chen Shijie


    Grains in the slurry can be brought into cutting zone by steel wire with a certain speed to achieve the purpose of removing the workpiece material in the free abrasive wire sawing machining. Because its own of multi-strands characteristics,we use it to replace the steel wire to do slicing experiment. In this paper,multi-strands wire is made by seven metal wires and has many grooves on its surface. Compared with steel wire,it can carry more grains into cutting zone which is conducive to improving the slicing efficiency. We do some comparative slic-ing experiments by applying multi-strands wire (ϕ0.25 mm) and steel wire (ϕ0.25 mm) to cut optical glass (K9). The results show that slicing efficiency and the surface roughness of the workpiece sliced by using multi-strands wire are better than that by using steel wire,but the kerf width of the former is wider than that of the latter in the same experimental conditions.

  11. Fluoride and abrasive content in commonly used dentifrices on the Kenyan market.

    Mwaniki, D L; Opinya, G N


    About one decade ago, a heated debate on the appropriateness of fluoride dentifrices in Kenya culminated in the introduction of no-fluoride brands. Analysis of dentifrices that were available on the market in 1989/1990 confirmed two distinctly different categories, the fluoride and the low or no-fluoride types. Among the former, the mean ionic fluoride concentration ranged between 0.4 and 1.36 mg/g while the total fluoride concentration ranged between 1.15 and 114.68 mg/g. The low or no-fluoride dentifrices had less than 0.03 mg/g ionic fluoride and less than 2.14 mg/g total fluoride. The mean abrasive (powder) content ranged between 26.5 g% and 78.5 g%. The gel categories had markedly lower powder values than the pastes. The ash values of the powders ranged between 15.8 g% and 85 g% and did not have an obvious relationship with the powder content. Despite the obvious risk of increasing exposure to excessive fluoride among children, presently, the situation has reverted to the pre-debate time. Given the ubiquitous nature of ingestable fluoride in the region, provision of guidelines and guidance on the sale of dentifrices by the government and consumer organisations, and increased accountability of the manufacturers are recommended.

  12. Numerical Thermodynamic Analysis of Two-Phase Solid-Liquid Abrasive Flow Polishing in U-Type Tube

    Junye Li


    Full Text Available U-type tubes are widely used in military and civilian fields and the quality of the internal surface of their channel often determines the merits and performance of a machine in which they are incorporated. Abrasive flow polishing is an effective method for improving the channel surface quality of a U-type tube. Using the results of a numerical analysis of the thermodynamic energy balance equation of a two-phase solid-liquid flow, we carried out numerical simulations of the heat transfer and surface processing characteristics of a two-phase solid-liquid abrasive flow polishing of a U-type tube. The distribution cloud of the changes in the inlet turbulent kinetic energy, turbulence intensity, turbulent viscosity, and dynamic pressure near the wall of the tube were obtained. The relationships between the temperature and the turbulent kinetic energy, between the turbulent kinetic energy and the velocity, and between the temperature and the processing velocity were also determined to develop a theoretical basis for controlling the quality of abrasive flow polishing.

  13. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method

    Haseog Kim


    Full Text Available There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5.

  14. cs of abrasive-reactive nanocomposite powder synthesis in the SiO2 − C/S system

    Faryt Urakaev


    Full Text Available In this study, the syntheses of cementite (Fe3C and pyrite (FeS2 have been performed by mechanical activation of a mixture of graphite or sulfur with amorphous or crystalline silica in a planetary ball mill AGO-2 with steel fittings. XRD analysis was used to record products and changes of systems components after mechanical activation of the studied systems. The formation of nanocomposites based on cementite (or pyrite has been recorded and the quantitative characteristics of abrasive-reactive wear of steel milling tools have been evaluated. It has been demonstrated the possibility of steel material reaction of milling tools for direct mechanochemical preparation of composite based on cementite using abrasive properties of silica modifications. It has obtained nanocomposites based on pyrite and glass matrix during mechanical activation of quartz glass and sulfur in a time of 1-2 orders of magnitude lower than traditional mechanical alloying powders of iron and sulfur. It can be noted that any scrap metal and ceramic products can be used as milling tools. This significantly enhances the ability of the proposed method of abrasive-reactive nanowear of milling tools materials of mechanochemical reactors and processed materials.

  15. The Optimum Production Method for Quality Improvement of Recycled Aggregates Using Sulfuric Acid and the Abrasion Method

    Kim, Haseog; Park, Sangki; Kim, Hayong


    There has been increased deconstruction and demolition of reinforced concrete structures due to the aging of the structures and redevelopment of urban areas resulting in the generation of massive amounts of construction. The production volume of waste concrete is projected to increase rapidly over 100 million tons by 2020. However, due to the high cement paste content, recycled aggregates have low density and high absorption ratio. They are mostly used for land reclamation purposes with low added value instead of multiple approaches. This study was performed to determine an effective method to remove cement paste from recycled aggregates by using the abrasion and substituting the process water with acidic water. The aim of this study is to analyze the quality of the recycled fine aggregates produced by a complex method and investigate the optimum manufacturing conditions for recycled fine aggregates based on the design of experiment. The experimental parameters considered were water ratio, coarse aggregate ratio, and abrasion time and, as a result of the experiment, data concerning the properties of recycled sand were obtained. It was found that high-quality recycled fine aggregates can be obtained with 8.57 min of abrasion-crusher time and a recycled coarse aggregate ratio of over 1.5. PMID:27483298

  16. Trajectories and energy transfer of saltating particles onto rock surfaces : application to abrasion and ventifact formation on Earth and Mars

    Bridges, Nathan T.; Phoreman, James; White, Bruce R.; Greeley, Ronald; Eddlemon, Eric E.; Wilson, Gregory R.; Meyer, Christine J.


    The interaction between saltating sand grains and rock surfaces is assessed to gauge relative abrasion potential as a function of rock shape, wind speed, grain size, and planetary environment. Many kinetic energy height profiles for impacts exhibit a distinctive increase, or kink, a few centimeters above the surface, consistent with previous field, wind tunnel, and theoretical investigations. The height of the kink observed in natural and wind tunnel settings is greater than predictions by a factor of 2 or more, probably because of enhanced bouncing off hard ground surfaces. Rebounded grains increase the effective flux and relative kinetic energy for intermediate slope angles. Whether abrasion occurs, as opposed to simple grain impact with little or no mass lost from the rock, depends on whether the grain kinetic energy (EG) exceeds a critical value (EC), as well as the flux of grains with energies above EC. The magnitude of abrasion and the shape change of the rock over time depends on this flux and the value of EG > EC. Considering the potential range of particle sizes and wind speeds, the predicted kinetic energies of saltating sand hitting rocks overlap on Earth and Mars. However, when limited to the most likely grain sizes and threshold conditions, our results agree with previous work and show that kinetic energies are about an order of magnitude greater on Mars.

  17. 高硼低碳耐磨合金磨料磨损性能研究%Study on Abrasive Wear Performance of High Boron Low Carbon Wear-resistant Alloy

    麻健梅; 王顺波; 苏广才; 汤宏群


    借助光学显微镜和SEM电镜观察,运用磨损试验手段及对比研究法,研究了高硼低碳耐磨合金的磨料磨损性能.结果表明,在中、低冲击工况下,高硼低碳耐磨合金的磨损质量损失、相对磨损率均小于高铬铸铁和高锰钢,且磨面磨损形成的沟槽少,压坑小,这显示出了良好的耐磨料磨损性.%The high boron low carbon wear-resistant alloy abrasive wear performance was researched by OM, SEM observation, wear test methods and comparision approach. The results show that in the medium or low impact conditions, the wear mass loss and relative wear rate of high boron low carbon wear-resistant alloy are less than that of high chromium cast iron and high manganese steel. The number of the wear grooves and the pits on the wear surface morphology is smaller, which shows the good characteristics in abrasive wear performance of high boron low carbon wear-resistant alloy.

  18. Effects of airborne-particle abrasion, sodium hydroxide anodization, and electrical discharge machining on porcelain adherence to cast commercially pure titanium.

    Acar, Asli; Inan, Ozgür; Halkaci, Selçuk


    The aim of this study was to determine the effect of airborne-particle abrasion (APA), sodium hydroxide anodization (SHA), and electrical discharge machining (EDM) on cast titanium surfaces and titanium-porcelain adhesion. Ninety titanium specimens were cast with pure titanium and the alpha-case layer was removed. Specimens were randomly divided into three groups. Ten specimens from each group were subjected to APA. SHA was applied to the second subgroups, and the remaining specimens were subjected to the EDM. For the control group, 10 specimens were cast using NiCr alloy and subjected to only APA. Surfaces were examined by using scanning electron microscope and a surface profilometer. Three titanium porcelains were fused on the titanium surfaces, whereas NiCr specimens were covered with conventional porcelain. Titanium-porcelain adhesion was characterized by a 3-point bending test. Statistical analysis showed that the porcelain-metal bond strength of the control group was higher than that of the titanium-porcelain system (p < 0.05). There were no significant differences between the bond strengths of titanium groups (p 0.05), except the bond strengths of Noritake Super Porcelain TI-22 groups on which APA and SHA were applied (p < 0.05). SHA and EDM as surface treatment did not improve titanium-porcelain adhesion when compared to APA.

  19. Application of the total etching technique or self-etching primers on primary teeth after air abrasion Aplicação da técnica de condicionamento total ou de "primers" autocondicionantes em dentes decíduos após abrasão a ar

    Fábio Renato Manzolli Leite


    Full Text Available Since the use of air abrasion has grown in pediatric dentistry, the aim of this study was to evaluate, by means of shear bond strength testing, the need to use the total etching technique or self-etching primers on dentin of primary teeth after air abrasion. Twenty-five exfoliated primary molars had their occlusal dentin exposed by trimming and polishing. Specimens were treated by: Air abrasion + Scotchbond MultiPurpose adhesive (G1; 37% phosphoric acid + Scotchbond MP adhesive (G2; Clearfil SE (G3; Air abrasion + 37% phosphoric acid + Scotchbond MP adhesive (G4; Air abrasion + Clearfil SE (G5. On the treated surface, a cylinder of 2 mm by 6 mm was made using a composite resin (Z100. Duncan's test showed that: (G2 = G3 = G5 > (G1 = G4. The use of a self-etching primer on air abraded dentin is recommended to obtain higher bond strengths.Como o uso da abrasão a ar tem aumentado em odontopediatria, o objetivo deste trabalho foi avaliar a resistência ao cisalhamento da resina composta Z100 sobre a superfície dentinária de dentes decíduos após abrasionamento a ar associado ou não a técnica de condicionamento total (ácido fosfórico + Scotchbond Multi Purpose ou "primer" autocondicionante (Clearfil SE Bond. A superfície oclusal de 25 molares decíduos foi removida para exposição completa da superfície dentinária. Após polimento com lixas abrasivas, foram divididos em 5 grupos (5 espécimes em cada tratados por abrasão + adesivo Scotchbond (G1; condicionamento ácido + adesivo Scotchbond (G2; adesivo Clearfil (G3; abrasão a ar + condicionamento ácido + adesivo Scotchbond (G4; abrasão a ar + adesivo Clearfil (G5. Uma matriz bipartida foi adaptada à superfície dentinária e preenchida com resina composta. Após polimerização, corpos-de-prova de 2 mm x 6 mm foram obtidos. O teste de Duncan mostrou a desigualdade (G1 = G4 < (G2 = G3 = G5. Desse modo, conclui-se que, após o abrasionamento dentinário, deve ser utilizado o sistema de

  20. 微磨料水射流切割头装置设计与研究%Design and research on cutting head for micro abrasive water jet

    刘克福; 雷玉勇; 蒋代君


    In traditional culling head for abrasive water jet,abrasives are usually fed into the cutting head by negative pressure, which is poor in re liability, non-uniform in suction,and unavailable precise in control of the abrasive flow rate.A new type of cutting head for micro abrasive water jet and its control sys-tem are designed based on screw pumping principle And an auger mechanism is used to feed the abrasives initiatively, which is driven by an electrical step motor and the rotating speed of the step motor is regulated through control pulse sent by MCU.The flow rate of abrasives and the rotating speed of step motor are cor-responding one by one.Therefore, the abrasives can be fed to the mixing chamber quantitatively and contin-uously so that the flow rate of abrasives can be precisely controlled.The method of setting one-way valve on the outlet duct of mixing chamber may prevent high pressure water from flowing into supply tank after the clogging of the nozzle, and thus the invalidation problem of the abrasive feed system is solved effectively.%传统磨料水射流切割头的磨料靠负压吸入,可靠性差、吸入不均匀、流量不能精确控制.采用螺杆泵输送原理,设计了一种新型微磨料水射流切割头装置及控制系统.该装置采用螺杆泵主动送料,螺杆由步进电机驱动,单片机发出的控制脉冲控制步进电机的转速,步进电机的转速与磨料流量一一对应,从而将磨料定量、连续地送到切割头混合腔,实现磨料流量的精确控制.在混合腔的排出通道上设置单向阀门,解决了啧嘴堵塞后高压水直接进入磨料罐引起磨料输送系统失效问题.

  1. Influence of secondary carbide precipitation and transformation on abrasion resistance of a 3Cr15Mo1V1.5 white iron

    Haohuai Liu; Jun Wang; Baoluo Shen; Hongshan Yang; Shengji Gao; Sijiu Huang


    The relationship between the secondary carbide precipitation and transformation of the 3Cr15Mo1V1.5 white iron and abrasion resistance was investigated by using optical microscope (OM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the properties of secondary carbides precipitated at holding stage play an important role in the abrasion resistance. After certain holding time at 833 K subcritical treatment, the grainy (Fe, Cr)23C6 carbide precipitated and the fresh martensite transformed at the holding stage for 3Cr15Mo1V1.5 white iron improve the bulk hardness and abrasion resistance of the alloy. Prolonging holding time, MoC and (Cr, V)2C precipitations cause the secondary hardening peak and the corresponding better abrasion resistance. Finally, granular (Fe, Cr)23C6 carbide in situ transforms into laminar M3C carbide and the matrix structure transforms into pearlitic matrix. These changes weaken hardness and abrasion resistance of the alloy sharply.

  2. Mobile load simulators - A tool to distinguish between the emissions due to abrasion and resuspension of PM10 from road surfaces

    Gehrig, R.; Zeyer, K.; Bukowiecki, N.; Lienemann, P.; Poulikakos, L. D.; Furger, M.; Buchmann, B.


    Mechanically produced abrasion particles and resuspension processes are responsible for a significant part of the PM10 emissions of road traffic. However, specific differentiation between PM10 emissions due to abrasion and resuspension from road pavement is very difficult due to their similar elemental composition and highly correlated variation in time. In this work Mobile Load Simulators were used to estimate PM10 emission factors for pavement abrasion and resuspension on different pavement types for light and heavy duty vehicles. From the experiments it was derived that particle emissions due to abrasion from pavements in good condition are quite low in the range of only a few mg·km -1 per vehicle if quantifiable at all. Considerable abrasion emissions, however, can occur from damaged pavements. Resuspension of deposited dust can cause high and extremely variable particle emissions depending strongly on the dirt load of the road surface. Porous pavements seem to retain deposited dust better than dense pavements, thus leading to lower emissions due to resuspension compared to pavements with a dense structure (e.g. asphalt concrete). Tyre wear seemed not to be a quantitatively significant source of PM10 emissions from road traffic.

  3. Researches concerning the ultasonic energy influence on the resistence to the abrasive wear of loaded welded parts

    Gh. Amza


    Full Text Available The researches presented in the paper refer to the effect of ultrasounds propagation in the liquid metal bath on the process of transferring the additive material through the electric arch and on the crystallization process, and all these effects are analyzed for loaded welded parts solicited at the abrasive wear. All these influences are conferred to these two basic phenomena due to the ultrasounds propagation in liquid environments, namely, ultra-acoustic cavitation and acceleration of the diffusion process. The results concerns the resistance to the wear obtained for the loaded parts through manual welding with electric arch and classically covered electrode and ultrasonically activated.

  4. Formation of abrasive hollow particles in lignite-fired fluidised bed boilers; Bildung abrasiver Hohlpartikel in braunkohlenbefeuerten Wirbelschichtkessel

    Kappler, Uta [RWE Power AG, Koeln (Germany). Forschung und Entwicklung Hauptverwaltung; Roeper, Bernhard [RWE Power AG, Grevenbroich (Germany). Technische Dienste Kraftwerk Frimmersdorf; Voss, Petra [RWE Power AG, Bergheim (Germany). Forschung und Entwicklung Kraftwerk Niederaussem


    The formation of voluminous and highly abrasive hollow particles in raw-lignite-fired circulating fluidised-bed (CFB) boilers of RWE Power AG is a well-known phenomenon. Operational measures were taken to avoid particle formation and related damage. By the end of 2011 another boiler damage occurred. Within the scope of root cause analyses the hollow particles were investigated and a model for particle genesis was developed. Based on these results further measures for the avoidance of particle formation were shown. The formation probability of similar hollow particles in biomass-fired fluidised-bed plants was assessed theoretically.

  5. Research on the Effectiveness of Cleaning Cutting Fluid Used for Machining During Abrasive and Diamond Tools Operations

    Vykintas Dusevičius


    Full Text Available The article presents the problem of cleaning effectively lubricant - coolant fluid using two different metal-working techniques. Compared with lubricant-coolant fluid, the use of steel abrasive tools produces very small steel particles having relative weight. Steel processing with diamond polishing tools does not make chips. The paper considers theoretical cleaning methods and compares them with experimental results cleaning an additional flow of lubrication and cooling with a magnetic separator and hydro-cyclone.Article in Lithuanian

  6. Core/shell composites with polystyrene cores and meso-silica shells as abrasives for improved chemical mechanical polishing behavior

    Chen, Yang, E-mail:; Qin, Jiawei; Wang, Yayun; Li, Zefeng [Changzhou University, School of Material Science and Engineering (China)


    The core/shell-structured organic/inorganic composite abrasive has an important potential application in damage-free chemical mechanical polishing (CMP) due to its non-rigid mechanical property. In this work, the PS/{sub M}SiO{sub 2} composites, containing polystyrene (PS) sphere (211 ± 4 nm) cores and mesoporous silica shells (31 ± 3 nm in thickness) were synthesized through directed surface sol–gel process of tetraethylorthosilicate on the polymer cores in the presence of the cetyltrimethylammonium bromide surfactant. For comparison, the conventional core/shell PS/{sub N}SiO{sub 2} composites with non-porous silica shells were also prepared via a modified Stöber procedure that involved the hydrolysis of TEOS under acidic condition. The physical properties of the samples were examined by small-angle X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy, and nitrogen adsorption–desorption. As novel abrasives, the core/shell-structured PS/{sub M}SiO{sub 2} composites were introduced into the CMP process for silicon oxide films. The oxide-CMP performance among conventional solid silica particles, PS/{sub N}SiO{sub 2} composites, and novel PS/{sub M}SiO{sub 2} composites was explored by atomic force microscopy. Polishing results indicated that the substrate revealed a comparable root-mean-square surface roughness (0.25 ± 0.03 and 0.22 ± 0.02 nm, respectively) after CMP with PS/{sub N}SiO{sub 2} and PS/{sub M}SiO{sub 2} abrasives under the same polishing conditions. However, the material removal rate of the PS/{sub M}SiO{sub 2} composites (123 ± 15 nm/min) was about three times larger than that of the PS/{sub N}SiO{sub 2} composites (47 ± 13 nm/min). The reduced surface roughness and improved removal rate might be due to the optimization of the physical and/or chemical environments in the local contacting region between abrasives

  7. Effect of Nano-sized CeO2 Abrasives on Chemical Mechanical Polishing of Silicon Wafer

    ZHANG Bao-sen; CHEN Yang


    The conception of the soft layer during chemical mechanical polishing(CMP) was proposed for the first time. The soft layer was a reaction layer formed on the silicon surface; it was softer than the silicon substrate and its thickness was about several nanometers. The existence of the soft layer could increase the material volume removed by one particle and increase the material removal rate during CMP. At the same time, the soft layer could decrease the cutting depth of the abrasive particle so as to realize ductile grinding, and it is useful to decrease the roughness of the polished surface and to improve the polishing quality.

  8. Adhesion analysis of polycrystalline diamond films on molybdenum by means of scratch, indentation and sand abrasion testing

    Buijnsters, J.G.; Shankar, P.; Enckevort, W.J.P. van; Schermer, J.J.; Meulen, J.J. ter


    Diamond films have been grown by hot-filament chemical vapour deposition (CVD) on molybdenum substrates under different growth conditions. The films grown with increasing substrate temperatures show a higher interconnection of diamond grains, whereas increasing methane concentrations in the 0.5-4.0%

  9. Thickness-Independent Ultrasonic Imaging Applied to Abrasive Cut-Off Wheels: An Advanced Aerospace Materials Characterization Method for the Abrasives Industry. A NASA Lewis Research Center Technology Transfer Case History

    Roth, Don J.; Farmer, Donald A.


    Abrasive cut-off wheels are at times unintentionally manufactured with nonuniformity that is difficult to identify and sufficiently characterize without time-consuming, destructive examination. One particular nonuniformity is a density variation condition occurring around the wheel circumference or along the radius, or both. This density variation, depending on its severity, can cause wheel warpage and wheel vibration resulting in unacceptable performance and perhaps premature failure of the wheel. Conventional nondestructive evaluation methods such as ultrasonic c-scan imaging and film radiography are inaccurate in their attempts at characterizing the density variation because a superimposing thickness variation exists as well in the wheel. In this article, the single transducer thickness-independent ultrasonic imaging method, developed specifically to allow more accurate characterization of aerospace components, is shown to precisely characterize the extent of the density variation in a cut-off wheel having a superimposing thickness variation. The method thereby has potential as an effective quality control tool in the abrasives industry for the wheel manufacturer.

  10. O efeito do jateamento do esmalte na força de adesão na colagem de braquetes The effect of air abrasion in enamel adhesion of orthodontic bracket

    Carla D'Agostini Derech


    Full Text Available OBJETIVO: o propósito deste estudo in vitro foi avaliar o efeito do jateamento com óxido de alumínio na adesão de braquetes ortodônticos e compará-lo à tradicional técnica de condicionamento ácido do esmalte. METODOLOGIA: foram utilizados 80 dentes bovinos distribuídos aleatoriamente entre quatro grupos, sendo que a superfície do esmalte foi tratada da seguinte maneira: grupo 1 (somente jateamento com óxido de alumínio, grupo 2 (profilaxia com pedra-pomes e condicionamento com ácido, grupo 3 (jateamento com óxido de alumínio e condicionamento ácido e grupo 4 (somente condicionamento ácido. Após, foi aplicado sistema adesivo e o braquete colado com resina. Os corpos-de-prova foram submetidos ao teste de cisalhamento e análise do IAR. Aos resultados foram aplicados o teste de variância múltipla (ANOVA e a comparação entre pares (Tukey. Para a análise do IAR foi aplicado o teste Qui-quadrado. RESULTADOS: o grupo 1 apresentou a menor resistência ao cisalhamento (3,6MPa e o 3 a maior (13,27MPa. A análise Qui-quadrado do IAR demonstrou que o tratamento da superfície do esmalte tem influência sobre a quantidade de remanescente de resina sobre o esmalte e os grupos 3 e 4 apresentaram a maior quantidade de resina aderida. CONCLUSÕES: o jateamento de óxido de alumínio não deve ser o único procedimento utilizado no preparo da superfície do esmalte na colagem de braquetes, porém, quando associado ao condicionamento ácido, mostrou-se eficaz no aumento da retenção entre esmalte e resina. Novos estudos são necessários visando menor dano do esmalte e adesão satisfatória.AIM: The purpose of this study in vitro was to evaluate the effect of the air abrasion with Al-oxide in the adhesion of orthodontic brackets and compare with traditional technique of acid conditioning of the enamel. METHODS: Eighty bovine teeth distributed randomly between four groups had been used and the surface of the enamel was prepared in the

  11. Research on Motion of Abrasive in Post-mixed Abrasive Water Jet%基于后混合式磨料水射流磨料颗粒运动研究

    潘峥正; 万庆丰; 雷玉勇; 蒋代君; 陈忠敏


    In order to improve the cutting performance of the post-mixed abrasive water jet,the mathematical model of the abra-sive motion in the focusing tube was established and numerically simulated on the basis of theory of solid-fluid two phase flow by using FLUENT software module. The traditional control model of particle phase was optimized by a researching object of single particle in the focusing tube,and the basic movement condition of abrasive particle in the nozzle was obtained. Research results show that the abra-sive particles join the high-speed jet by the collision between each phase after they enter into the mixing chamber. Therefore two phase jet flow in the end is formed. Under the action of high speed water jet carrying,the speed of the particles will rise rapidly on initial forming stage of the two-phase flow. Due to causes of sudden change of internal structure in mixing chamber,phase velocity of particle has a big difference and is unsteady. After the particles enter into the focus tube through convergence section,the phase velocity of particle will exponentially approach the phase velocity of liquid jet and it will gradually be in steady. But because of causes of linear en-ergy loss along the path,phase velocity of particle has always slide away relatively to that of the liquid jet. The velocity of abrasive par-ticles is slightly slower than liquid jet speed after all.%为了改善后混合式磨料水射流的切割性能,以固液两相流理论为基础,通过FLUENT模块对喷嘴内磨料的运动进行建模和数值分析。以聚焦管内的单个颗粒为研究对象,优化传统的颗粒相控制模型,获得磨料颗粒在喷嘴内基本的运动情况。研究表明,磨料颗粒吸入混合腔后通过各相之间的碰撞进入高压射流,形成液固两相流。两相流形成初期,磨料颗粒的速度在高压水射流的携带作用下迅速上升。由于混合腔内部结构突变等原因,颗粒相速度浮动较

  12. Heat treatment process optimization of roller material of wheat mill against abrasive wear%小麦磨粉机磨辊材料抗磨损热处理工艺优化

    张克平; 姜良朋; 黄晓鹏


    植物磨料磨损是辊式制粉工业中磨辊磨损失效的主要原因,热处理工艺是磨辊材料(低铬白口铁)表面硬度强化的一般手段。该文选用与辊式制粉工况相似的磨损试验机进行试验,利用正交试验考察了不同工艺参数热加工对低铬白口铁抗小麦粉料磨损性能的影响,并择选出最优工艺组合。基于最优工艺组合,以低铬白口铁原始件为参照,综合质量损失、磨痕特征及扫描电镜形貌等手段提取磨损特征,考察最优热处理工艺对低铬白口铁抗小麦粉料磨损性能的强化效果。试验推荐最优热处理工艺组合为:960℃(1 h)空淬+250℃(2 h)回火,实际生产推荐最优热处理工艺组合为:基于960℃淬火+250℃回火的表面热加工;经最优热加工工艺处理的低铬白口铁的磨损质量损失约为原始试样质量损失的42%,铸态组织内共晶碳化物断网现象明显,以半连续网状或孤立块状分布于基体;被磨面沟槽宽深度与棱脊峰谷值等磨痕特征及金属元素含量有所降低,试样硬度显著增加;磨损形式主要为微观切削、多次塑性变形与低周期疲劳磨损。该研究可为磨辊耐磨性能的提升以及降低加工过程对面粉的金属污染提供参考。%The wear of plant abrasive is the main reason to roller wear failure in wheat roller milling industry, while the heat treatment is the general strengthening means of surface hardness of low chromium white iron which is usually used as roller material. In this paper, 3 principles of abrasive wear were applied, and low chromium white iron was chosen as the test samples and wheat powder was chosen as abrasive. The wear test was conducted on wear test machine under the similar work process of industrial roller milling. The test was divided into 2 phases. In the first phase, 9 groups of samples were heat treated with different process parameters according to the

  13. U-Pb dating by zircon dissolution method using chemical abrasion

    Lucy Takehara


    Full Text Available Chemical abrasion was carried out on zircons grains of the Temora II standard for U-Pb dating prior to analyses using in situ Laser Ablation-MultiCollector Ion Coupled Plasma Mass Spectrometer (LA-ICPMS followed by the Isotope Dissolution Thermal Ionization Mass Spectrometer (ID-TIMS method. The proposed methodology was herein applied in order to reduce primarily the effects of secondary Pb loss, the presence of common lead and/or silicate impurities. Nine Temora II zircon grains were analyzed by the laser ablation method yielding an age of 418.3±4.3 Ma. Zircon grains of a same population were separated for chemical abrasion before dissolution and mass spectrometry analyses. Six fractions of them were separated for isotope dissolution using 235U-205Pb mixed spike after we have checked and assured the laboratory conditions of low blank values for total Pb of less than 2 pg/g. The obtained U-Pb zircon age by the ID-TIMS method was 415.7±1.8 Ma (error 0.43 % based on four successful determinations. The results are consistent with the published ages for the Temora diorite (Temora I – 416.75±1.3 Ma; Temora II – 416.78±0.33 Ma and established as 416±0.33 Ma. The technique is thus recommended for high precision U-Pb zircon analyses (error Este trabalho apresenta a técnica de abrasão química em zircões do padrão Temora II aplicada em datação de U-Pb por Dissolução Isotópica e Espectrometria de Massa por Ionização Térmica, método DI-ESIT. O emprego deste método tem como princípio diminuir os efeitos da perda secundária de Pb radiogênico antes da dissolução. Em primeira instância, os zircões foram analisados pelo método in situ com uso de Microssonda Laser acoplada a um Espectrômetro de Massa Multicoletor com Plasma Acoplado Indutivamente (MC-ICP-MS, cujo objetivo foi identificar os grãos de zircão de fase de cristalização simples sem sobrecrescimento. Nove cristais de zircão analisados com microssonda a

  14. 三元乙丙橡胶耐磨性能研究%Study on the Abrasion of EPDM Rubblers

    褚夫强; 李庄; 曾飞


    研究了生胶品种、硫化体系、填充体系和加工助剂等因素对三元乙丙橡胶耐磨性能的影响.实验结果表明:胶种选用高乙烯含量,高门尼粘度的非充油型乙丙橡胶,硫化体系采用硫磺/硫载体并用的有效硫磺硫化体系,填充体系采用高结构炭黑N220以及Si-69改性过的气相法白炭黑AS-200并用体系,同时配合0.5份左右的爽滑粉,都能有效提高EPDM胶料的耐磨性能.%The effects of the raw rubber variety,curing system,filling systems and processing aids and other factors on the abrasion of EPDM were studied.The results of experiments show that with high ethylene content and Mooney viscosity non-oil-filled EPDM as raw rubber,sulfur/sulfur carrier as curing system,carbon black(N220) and Si 69 modified fumed silica (AS-200) as filler,plus 0.5 phr smooth powder,the abrasion of EPDM is improved.

  15. An experimental study on the ultra-precision polishing of quartz crystal using MR fluids and micro abrasives

    Kim, D. W.; Lee, J. W.; Cho, M. W.; Choi, S. B.


    This paper presents ultra-precision MR polishing results of quartz crystal, which has been widely used in many applications, such as piezo-electric transducer, surface acoustic wave (SAW) filters and SAW resonators, etc. It is known that smooth surface with sub-nanometer roughness is needed for higher-frequency application. The MR fluids, used for the polishing, consist of DI water based carbonyl iron (CI), nonmagnetic polishing micro abrasives, and required amount of stabilizers. In the process, mixed fluids were supplied into the gap between a rotating wheel (with electromagnetic field) and the workpiece. Then, the micro abrasives contained in the fluids perform material removal action from the workpiece. Such material removal mechanism in the MR polishing is considered as a process governed by the Bingham flow in the contact zone. In this study, material removal characteristics and generated surface roughness of the quartz crystal specimens using the MR polishing process were investigated through a series of experiments. The surface roughness variations of the polished specimens were investigated by changing imposed polishing conditions, such as wheel speed, magnetic field intensity. As a result, very fine surface roughness of Ra=0.770nm was obtained.

  16. Effect of the CaF2-fraction in the glass-ceramic with abrasion resistance on crystallization

    HU Bin-liang; Zhao Yun-cai


    Investigated the effect of an addition of CaF2 on the crystallization of a glass-ceramic with abrasion resistance. X-ray diffraction, differential thermal analysis and scanning electron microscopy were used to determine the effect. The results showed that a suitable addition of CaF2 promoted crystallization by forming an intermediate crystalline phase. CaF2 can decrease the temperature and active energy of the base-glass for crystallization. When 4 mass-% of CaF2-fraction is added in the glass, the crystallization temperature and active energy is 936℃and 172.75 k J/mol respectively.When CaF2 is increased to 6 mass-%, the temperature and active energy decrease to 890℃ and 88.81 kJ/mol. CaF2 is an efficient nucleating agent for the glass-ceramics with abrasion resistant, the optimal content of CaF2 is about 6 mass-%.

  17. Elliptic hole abrasive belt chamfer machine tool%椭圆孔砂带倒角机床

    王友林; 姜英


    From the structure and working principle, etc, this paper introduced a machine tool that machining elliptic hole on small end bevel face of link, using ductile deformation of abrasive belt method to substitute the additional movement of cutting tool or the workpiece along the long axis of elliptic hole, the edge of elliptic hole is removed by grinding material on abrasive belt under the influence of movement and pressure , obtain a chamfer plane, achieve machining of elliptic hole chamfer.%从结构、工作原理等方面介绍了一种用于连杆小头斜端面上的椭圆孔的倒角加工机床,利用砂带的挠性变形替代加工中刀具或工件沿椭圆的长轴移动的附加运动,工件端面上椭圆孔的棱边在砂带的压力与运动作用下被砂带上的磨料切除,形成倒角平面,实现了椭圆形孔的倒角加工.

  18. Halogen-Free Phosphonate Ionic Liquids as Precursors of Abrasion Resistant Surface Layers on AZ31B Magnesium Alloy

    Tulia Espinosa


    Full Text Available Surface coatings formed by immersion in the ionic liquids (ILs 1,3-dimethylimidazolium methylphosphonate (LMP101, 1-ethyl-3-methylimidazolium methylphosphonate (LMP102 and 1-ethyl-3-methylimidazolium ethylphosphonate (LEP102 on magnesium alloy AZ31B at 50 °C have been studied. The purpose of increasing the temperature was to reduce the immersion time, from 14 days at room temperature, to 48 hours at 50 °C. The abrasion resistance of the coated alloy was studied by microscratching under progressively increasing load, and compared with that of the uncoated material. The order of abrasion resistance as a function of the IL is LEP102 > LMP101 > LMP102, which is in agreement with the order obtained for the coatings grown at room temperature. The maximum reduction in penetration depth with respect to the uncovered alloy, of a 44.5%, is obtained for the sample treated with the ethylphosphonate LEP102. However, this reduction is lower than that obtained when the coating is grown at room temperature. This is attributed to the increased thickness and lower adhesion of the coatings obtained at 50 °C, particularly those obtained from methylphosphonate ionic liquids. The results are discussed from SEM-EDX and profilometry.

  19. Investigation of Noise Level and Penetration Rate of Pneumatic Drill vis-à-vis Rock Compressive Strength and Abrasivity

    Kivade, S. B.; Murthy, Ch. S. N.; Vardhan, H.


    In this paper, detailed studies were carried out to determine the influence of rock properties on the sound level produced during pneumatic drilling. Further, investigation was also carried out on the effect of thrust, air pressure and compressive strength on penetration rate and the sound level produced. For this purpose, a fabricated pneumatic drill set up available in the institute was used. Rock properties, like compressive strength and abrasivity, of various samples collected from the field were determined in the laboratory. Drilling experiments were carried out on ten different rock samples for varying thrust and air pressure values and the corresponding A-weighted equivalent continuous sound levels were measured. It was observed that, very low thrust results in low penetration rate. Even very high thrust does not produce high penetration rate at higher operating air pressures. With increase in thrust beyond the optimum level, the penetration rate starts decreasing and causes the drill bit to `stall'. Results of the study show that penetration rate and sound level increases with increase in the thrust level. After reaching the maximum, they start decreasing despite the increase of thrust. The main purpose of the study is to develop a general prediction model and to investigate the relationships between sound level produced during drilling and physical properties such as uniaxial compressive strength and abrasivity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of predictor variables.

  20. Analysis Of The Austenite Grain Growth In Low-Alloy Boron Steel With High Resistance To Abrasive Wear

    Białobrzeska B.


    Full Text Available Today low-alloy steels with boron achieve high resistance to abrasive wear and high strength. These features are obtained by using advanced technology of manufacturing. This makes boron steels increasingly popular and their application more diverse. Application of these steels can extend the lifetime of very expensive machine construction in many industries such as mining, the automotive, and agriculture industries. An interesting subgroup of these materials is steel with boron intended for heat treatment. These steels are supplied by the manufacturer after cold or hot rolling so that it is possible for them to be heat treated in a suitable manner by the purchaser for its specific application. Very important factor that determines the mechanical properties of final product is austenite grain growth occurring during hot working process such us quenching or hot rolling. Investigation of the effect of heating temperature and holding time on the austenite grain size is necessary to understand the growth behavior under different conditions. This article presents the result of investigation of austenite grain growth in selected low-allow boron steel with high resistance to abrasive wear and attempts to describe the influence of chemical composition on this process.

  1. Electrochemical behavior and polishing properties of silicon wafer in alkaline slurry with abrasive CeO2

    SONG Xiao-lan; XU Da-yu; ZHANG Xiao-wei; SHI Xun-da; JIANG Nan; QIU Guan-zhou


    The electrochemical behavior of silicon wafer in alkaline slurry with nano-sized CeO2 abrasive was investigated. The variations of corrosion potential (φcorr) and corrosion current density (Jcorr) of the P-type (100) silicon wafer with the slurry pH value and the concentration of abrasive CeO2 were studied by polarization curve technologies. The dependence of the polishing rate on the pH and the concentration of CeO2 in slurries during chemical mechanical polishing(CMP) were also studied. It is discovered that there is a large change of φcorr and Jcorr when slurry pH is altered and the Jcorr reaches the maximum (1.306 μA/cm2) at pH 10.5 when the material removal rate(MRR) comes to the fastest value. The Jcorr increases gradually from 0.994 μA/cm2 with 1% CeO2 to 1.304 μA/cm2 with 3% CeO2 and reaches a plateau with the further increase of CeO2 concentration. There is a considerable MRR in the slurry with 3% CeO2 at pH 10.5. The coherence between Jcorr and MRR elucidates that the research on the electrochemical behavior of silicon wafers in the alkaline slurry could offer theoretic guidance on silicon polishing rate and ensure to adjust optimal components of slurry.

  2. Effects on Structure and Abrasion Resistance of GCr15 Steel by Surface Gas-Phase RE Diffused Permeation with Laser Melting Solidification


    The effects on abrasion resistance and the microstructure of GCr15 steel surface by the compound technology of permeating RE combined with laser melting modification was studied. The results show that after compound treatment, the abrasion resistance of samples has been improved significantly and the weight loss has been reduced to 14% of blank sample; the microstructure has been denser and more uniform than that of untreated; meanwhile, the grain has been refined and the concentration gradients of the elements permeated have been decreased obviously.

  3. Evaluation of dentifrice abrasion on human dentin and teeth enamel; Determinacao da abrasividade de dentifricios em dentina e esmalte de dentes humanos

    Camargo, Iara M.C. de; Saiki, Mitiko; Vasconcellos, Marina B.A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)


    Radiometric method is applied to the dentifrice abrasion indicators evaluation: radioactive dentin (RDA) and radioactive enamel abrasion (REA). The dentifrices analysed presented RDA values varying from 95 to 13 and REA values from 7.1 to 0.7, showing a good precision, generally with relative standard deviations lower than 15.4%. Also, the dentifrices were classified as having low and medium cleaning potential. A correlation between RDA and REA values was obtained, i.e. dentifrices with high RDA values presented high REA ones. (author). 6 refs., 3 tabs.

  4. Effects of neoprene mat on diarrhea, mortality and foreleg abrasion of pre-weaning piglets.

    Gu, Zhaobing; Xin, Hongwei; Wang, Chaoyuan; Shi, Zhengxiang; Liu, Zuohua; Yang, Feiyun; Lin, Baozhong; Wang, Chao; Li, Baoming


    Modern commercial swine farrowing crates are typically equipped with slatted iron floor to improve management efficiency (e.g., ease of manure handling, cleanliness of the farrowing crates and hence improved animal hygiene). However, the bare and hard floor surface can impair the welfare of the sow-litter because of some undesirable impacts on the pigs, such as foreleg abrasion, large temperature gradients between the cold floor surface and the abdomen of the piglets (hence higher susceptibility to diarrhea), and higher pre-weaning mortality or morbidity. Although straw bedding has been shown to be conducive to providing better environment for the sow-litter, use of straw creates challenges in terms of economics, hygiene and manure handling. This study investigates the use of neoprene mat (NM) in key areas of the farrowing crates - underneath the sow and in the piglet suckling area to improve the microenvironment and hence welfare of the sow-litter. Two experiments were conducted, each involving 12 sow-litters. The first experiment was to evaluate the thickness of a rectangular-shaped NM (7, 10 or 13 mm) vs. the slatted iron floor (control or Ctrl) and collect the corresponding animal response data; while the second follow-up experiment was to verify the benefits of supplying an improved, double concave (or H)-shaped NM with 10mm thick (CNM10) vs. Ctrl for the farrowing operation. Results of both experiments demonstrated considerable benefits of the NM placement in the farrowing crates. Specifically, the NM reduced the piglet foreleg lesion area and joint swellings (0% for NM vs. 8-10% for Ctrl during suckling periods in both Expts 1 and 2, P<0.001); reduced pre-weaning piglet crushing mortality (18.5+/-5.0%, 6.7+/-3.3% and 9.1+/-5.2% and for Ctrl, NM7 and NM10 and in Expt 1, P<0.05); and reduced piglet diarrhea morbidity (0.6+/-0.2% for CNM10 vs. 2.7+/-0.3% for Ctrl in Expt 2, P<0.01). Piglets in the NM litters had smaller temperature gradients between the abdomen

  5. 通过测量电力输入预测磨料/工件界面的条件变化%Prediction of condition changes at abrasive/workpiece interface by measuring electric power input

    山本和; 近藤康雄; 上原一刚; 小幡文雄


    A monitoring system is proposed in order to detect the condition changes at abrasive/workpiece interface in abrasive cutoff operation. The system can detect the condition changes from the electric power change consumed by the driving motor of lapping tool. The electric power is strongly related with the abrasive effectiveness. When the abrasive effectiveness has been kept a normal state, the electric power also has been kept a constant value. The bodily removal of abrasive leads to reduce the electric power monotonously. The piling up of cutting chips leads to a peculiar electric power change; the electric power increased gradually at the beginning and then began to fluctuate periodically. The severe adhesion of cutting chips to the cutting edges leads to the loss of nominal function in the cutting edges and the electric power input was thus descended suddenly at an early stage of lapping.

  6. 钢渣高性能混凝土抗冲耐磨性能试验%Study on the abrasion resistant properties of high performance concrete with steel slag powder

    信玉良; 侍克斌; 努尔开力·依孜特罗甫; 吴福飞


    In order to use a large amount of industrial waste more efficiently, 15 groups of concrete specimens with different contents of steel slag powder ( SSP) were designed and produced. An experimental study with a special emphasizes on the influence of SSP contents on the workability, mechanical properties, and abrasion resistance of concrete was carried out. The test results showed that the workability of concrete could be improved by steel slag powder, and in the different water glue ratio, the early strength of concrete with steel slag powder is less than the reference concrete. When the dosage of steel slag is within 10%-30%, the late strength of concrete with steel slag powder is approximately equal or slightly higher than the reference concrete. While the dosage of steel slag is greater than 30%, the late strength of concrete decreased greatly. In this experiment, the concrete's anti-abrasion strength of 28 day is tested by high-speed under water method. The results show that anti abrasion strength of concrete with steel slag powder increases slightly than the benchmark concrete when the steel slag content within 10%. When the steel slag is greater than 20%, the anti-abrasion strength of concrete decreased. Therefore, when the steel slag poses as admixture of concrete, the volume should be controlled within 20%.%为有效利用大宗废料钢渣,设计制作了15组掺钢渣粉混凝土试件,试验研究钢渣粉掺量对混凝土的工作性能、力学性能及抗冲耐磨性能的影响极其作用机理。结果表明:钢渣粉可以改善混凝土的工作性能;在不同水胶比下,掺钢渣粉混凝土的早期强度均小于基准混凝土,钢渣掺量在10%~30%以内时,混凝土的后期强度与基准混凝土基本持平,且略有提高,钢渣掺量大于30%时混凝土的后期强度下降较大;采用水下钢球法测试混凝土28 d抗冲磨强度,得出钢渣掺量在10%以内时混凝土的抗冲磨强度比基准混凝

  7. The Impact of Retained Austenite Characteristics on the Two-Body Abrasive Wear Behavior of Ultrahigh Strength Bainitic Steels

    Narayanaswamy, Balaji; Hodgson, Peter; Timokhina, Ilana; Beladi, Hossein


    In the current study, a high-carbon, high-alloy steel (0.79 pct C, 1.5 pct Si, 1.98 pct Mn, 0.98 pct Cr, 0.24 pct Mo, 1.06 pct Al, and 1.58 pct Co in wt pct) was subjected to an isothermal bainitic transformation at a temperature range of 473 K to 623 K (200 °C to 350 °C), resulting in different fully bainitic microstructures consisting of bainitic ferrite and retained austenite. With a decrease in the transformation temperature, the microstructure was significantly refined from ~300 nm at 623 K (350 °C) to less than 60 nm at 473 K (200 °C), forming nanostructured bainitic microstructure. In addition, the morphology of retained austenite was progressively altered from film + blocky to an exclusive film morphology with a decrease in the temperature. This resulted in an enhanced wear resistance in nanobainitic microstructures formed at low transformation temperature, e.g., 473 K (200 °C). Meanwhile, it gradually deteriorated with an increase in the phase transformation temperature. This was mostly attributed to the retained austenite characteristics ( i.e., thin film vs blocky), which significantly altered their mechanical stability. The presence of blocky retained austenite at high transformation temperature, e.g., 623 K (350 °C) resulted in an early onset of TRIPing phenomenon during abrasion. This led to the formation of coarse martensite with irregular morphology, which is more vulnerable to crack initiation and propagation than that of martensite formed from the thin film austenite, e.g., 473 K (200 °C). This resulted in a pronounced material loss for the fully bainitic microstructures transformed at high temperature, e.g., 623 K (350 °C), leading to distinct sub-surface layer and friction coefficient curve characteristics. A comparison of the abrasive behavior of the fully bainitic microstructure formed at 623 K (350 °C) and fully pearlitic microstructure demonstrated a detrimental effect of blocky retained austenite with low mechanical stability on

  8. The effects of weathering on the strength and chemistry of Columbia River Basalts and their implications for Mars Exploration Rover Rock Abrasion Tool (RAT) results

    Thomson, B. J.; Hurowitz, J. A.; Baker, L. L.; Bridges, N. T.; Lennon, A. M.; Paulsen, G.; Zacny, K.


    Basalt physical properties such as compressive strength and density are directly linked to their chemistry and constitution; as weathering progresses, basalts gradually become weaker and transition from intact rock to saprolite and ultimately, to soil. Here we quantify the degree of weathering experienced by the Adirondack-class basalts at the Mars Exploration Rover Spirit site by performing comparative analyses on the strength and chemistry of a series of progressively weathered Columbia River Basalt (CRB) from western Idaho and eastern Washington. CRB samples were subjected to compressive strength tests, Rock Abrasion Tool grinds, neutron activation analysis, and inductively coupled plasma optical emission spectroscopy. Analyses of terrestrial basalts indicate linked strength-chemical changes, as expected. Weathering sufficient to induce the loss of more than 50% of some cations (including >50% of MgO and MnO as well as ∼38% of Fe2O3 and 34% of CaO) was observed to weaken these samples by as much as 50% of their original strength. In comparison with the terrestrial samples, Adirondack-class basalts are most similar to the weakest basalt samples measured in terms of compressive strength, yet they do not exhibit a commensurate amount of chemical alteration. Since fluvial and lacustrine activity in Gusev crater appears to have been limited after the emplacement of flood basalt lavas, the observed weakness is likely attributable to thin-film weathering on exposed, displaced rocks in the Gusev plains (in addition to some likely shock effects). The results indicate that Adirondack-class basalts may possess a several mm-thick weak outer rind encasing an interior that is more pristine than otherwise indicated, and also suggest that long rock residence times may be the norm.

  9. Estimation of the operational reliability determined with Weibull modulus based on the abrasive wear in a cylinder-piston ring system

    J. Piątkowski


    Full Text Available Purpose: The main purpose of the study was to determine methodology for estimation of the operational reliability based on the statistical results of abrasive wear testing.Design/methodology/approach: For research, a traditional tribological system, i.e. a friction pair of the AlSi17CuNiMg silumin in contact with the spheroidal graphite cast iron of EN-GJN-200 grade, was chosen. Conditions of dry friction were assumed. This system was chosen based on mechanical cooperation between the cylinder (silumin and piston rings (spheroidal graphite cast iron in conventional internal combustion piston engines with spark ignition.Findings: Using material parameters of the cylinder and piston rings, nominal losses qualifying the cylinder for repair and the maximum weight losses that can be smothered were determined. Based on the theoretical number of engine revolutions to repair and stress acting on the cylinder bearing surface, the maximum distance that the motor vehicle can travel before the seizure of the cylinder occurs was calculated. These results were the basis for statistical analysis carried out with the Weibull modulus, the end result of which was the estimation of material reliability (the survival probability of tribological system and the determination of a pre-operation warranty period of the tribological system.Research limitations/implications: The analysis of Weibull distribution modulus will estimate the reliability of a tribological cylinder-ring system enabled the determination of an approximate theoretical time of the combustion engine failure-free running.Originality/value: The results are valuable statistical data and methodology proposed in this paper can be used to determine a theoretical life time of the combustion engine.

  10. Chamfer machining of oval hole on small end of link by abrasive belt%连杆小端椭圆孔的砂带倒角加工

    王友林; 姜英


    分析了连杆小头斜端面上的椭圆孔倒角加工存在的问题,介绍了砂带倒角加工方法及椭圆孔砂带倒角机床的结构与工作原理;在砂带倒角机床上,利用砂带的挠性和卷曲变形,替代加工中刀具或工件沿椭圆的长轴移动的附加运动,工件端面上椭圆孔的棱边在砂带的压力与运动作用下被砂带上的磨料切除,形成倒角平面,实现了椭圆孔的倒角加工.%The chamfer of oval hole on oblique surface of small end of link method presented problems are analyzed, the structure and working principle of oval holes abrasive belt chamfering machine tool are introduced ,on the abrasive belt chamfering machine tool, using of the flexible deformation and curling deformation of abrasive belt method substitute that additional movement of cutting tool or the workpiece along the long axis of oval hole, the edge of oval hole be removed by grinding material on abrasive belt under the influence of movement and pressure, obtain a chamfer plane, achieve chamfer machining of oval hole.

  11. Development of Abrasion-Resistant Coating for Solar Reflective Films. Cooperative Research and Development Final Report, CRADA Number CRD-07-247

    Gray, Matthew [National Renewable Energy Lab. (NREL), Golden, CO (United States)


    The purpose of this CRADA is to develop an abrasion-resistant coating, suitable for use on polymeric-based reflective films (e.g., the ReflecTech reflective film), that allows for improved scratch resistance and enables the use of aggressive cleaning techniques (e.g., direct contact methods like brushing) without damaging the specular reflectance properties of the reflective film.

  12. 磨料水射流切割面粗糙度研究%Research on Surface Roughness in Abrasive Water Jet Cutting

    苗新刚; 武美萍; 缪小进


    It was investigated traverse speed and abrasive mass flow rate during abrasive water jet cuttingof aluminum on surface roughness. GMT garnet was used as abrasive material with 80 mesh. The experimental results show that traverse speed has the greatest effect on the surface roughness at the bottom of the cut. It was also researched the correlation between the surface roughness and other abrasive water jet cutting variables.%对在磨料水射流切割过程中进给速度和磨料流量两点进行了讨论。磨料颗粒采用直径为80目的石榴石。测量了切割不同深度的粗糙度。实验结果表明:对切割表面影响最大的是切割速度。同时也研究了切割面粗糙度和磨料水射流其他参数之间的关系。

  13. Air quality modelling as a tool used in selecting technological alternatives for developing a new abrasive facility

    Radu Mihăiescu


    Full Text Available Production of abrasive compounds employs the use of various organic materials as adhesivesor as conditioners. During the baking process, a significant amount of air pollutant substances, includingvarious forms of organic compounds are emitted in the atmosphere. Selecting the most suitabletechnological process is a procedure that involves a cost benefit analysis as well as procedures forcomplying with BAT requirements (best available techniques. Assessing the resulting environmentquality in the vicinity of a new facility is also important, IPPC Directive clearly specifies that a new facilitymust not induce changes of the quality of the environment. This is highly dependent on localmeteorological and topographical conditions. The ISCST3 model was applied to assess the atmosphericdispersions associated with several potential technological designs, and compare their impacts on theenvironment.

  14. Search for magnetic minerals in Martian rocks: Overview of the Rock Abrasion Tool (RAT) magnet investigation on Spirit and Opportunity

    Goetz, W.; Leer, K.; Gunnlaugsson, H.P.;


    The Rock Abrasion Tool (RAT) on board the Mars Exploration Rovers (MER) is a grinding tool designed to remove dust coatings and/or weathering rinds from rocks and expose fresh rock material. Four magnets of different strengths that are built into the structure of the RAT have been attracting...... substantial amounts of magnetic material during RAT activities from rocks throughout both rover missions. The RAT magnet experiment as performed on Spirit demonstrates the presence of a strongly ferrimagnetic phase in Gusev crater rocks, which based on Mossbauer and visible/near-infrared reflectance spectra...... is interpreted as magnetite. The amount of abraded rock material adhering to the magnets varied strongly during the mission and is correlated in a consistent way to the amount of magnetite inferred from Mossbauer spectra for the corresponding rock. The RAT magnet experiment as performed on Opportunity also...

  15. Field-Activated, Pressure-Assisted Synthesis of Ultra-hard, Super-Abrasive AlMgB14

    Liu, Wen; Wu, Yin-tao; Mao, Shu-hong; Pan, Rui-li; Zhang, Jing; Zhang, Tie-ming


    Mechanical alloying (MA) and the field-activated and pressure-assisted in situ synthesis (FAPAS) were combined to prepare the ultra-hard and super-abrasive AlMgB14 with the characteristics of fast heating-up, high efficiency, and low energy cost. Such preparations using the elemental constituents, such as Al, Mg, and B, were performed at a vacuum annealed temperature of 1500 °C under a pressure of 60 MPa. The resultant ceramics were characterized by SEM, EDS, and XRD. It was shown that the samples contained uniform AlMgB14, and the maximum hardness on the sample surface may reach 32.5 GPa. Furthermore, a second experiment was performed, in which MgH2 was used as one of the starting materials instead of elemental Mg, but this approach did not produce AlMgB14.

  16. Quantifying Sub-Glacial Abrasion at Jakobshavn Isbræ: A Novel Approach Using In Situ 10Be Measurements

    Young, N. E.; Briner, J. P.; Schaefer, J. M.


    Warm-based ice sheets and glaciers incontrovertibly erode and modify the terrain that they mantle; yet precise estimates of the rate and magnitude of sub-glacial erosion are rare. Estimates of sub-glacial erosion occurring beneath ice sheets, such as the Greenland Ice Sheet, are particularly important because they can provide key insights into sediment availability at ice-sheet margins that influences ice-sheet stability. Furthermore, estimates of sub-glacial erosion can help inform predictive geophysical ice-sheet models that incorporate a basal sliding parameter. Here, we take advantage of a detailed ice-margin history at Jakobshavn Isbræ over the last ~7,500 years, combined with in situ 10Be measurements from strategic bedrock locations, to quantify the rate of sub-glacial abrasion beneath Jakobshavn Isbræ's land-based margins. Our bedrock samples are from 1) locations that deglaciated ~7,500 years ago and have remained ice-free through present day, and 2) locations that also deglaciated ~7,500 years ago, but were re-occupied by the ice-margin during the last few hundred years. After accounting for the slightly different exposure histories between bedrock locations, and despite the short duration in ice-cover, initial 10Be measurements reveal a detectable difference in 10Be concentrations between the two bedrock surfaces. We hypothesize that the offset in 10Be concentrations reveals the magnitude of sub-glacial abrasion beneath Jakobshavn Isbræ's land-terminating margins.

  17. Evaluation of retention of pit and fissure sealants placed with and without air abrasion pretreatment in 6-8 year old children – An in vivo study

    Goswami, Mridula


    Background The success of pit and fissure sealants is directly related to their retention. The purpose of this study was to assess and compare the retention of pit and fissure sealants placed using acid etch alone and a combination of air abrasion and acid etch techniques. Material and Methods 50 subjects aged 6-8 years were included in the study. Primary second molars and permanent first molars were sealed in all four quadrants using split mouth design. The right maxillary and mandibular molars (Group A) were treated by acid etching alone while the left maxillary and mandibular molars (Group B) were pretreated with air abrasion followed by acid etching before application of pit and fissure sealant. Retention of sealants was checked using Simonsen’s criteria of sealant retention after three and six months of sealant application. Results There was no significant difference in retention of sealants in Group A and Group B (p0.05). Maxillary molars showed superior retention compared to mandibular molars, which was statistically significant at both three and six months (p<0.05). Conclusions Combining air abrasion pretreatment with subsequent acid etching did not result in statistically significant difference in sealant retention compared to acid etching alone in both primary and permanent molars after 3 and 6 months follow up. An additional air abrasion pretreatment step can be avoided in pediatric patients when placing sealants and the procedure can be completed faster with better behavior management using acid etching alone. Key words:Pit and fissure sealant, acid etching, air abrasion. PMID:28210438

  18. State-of-the-science review of the occupational health hazards of crystalline silica in abrasive blasting operations and related requirements for respiratory protection.

    Madl, Amy K; Donovan, Ellen P; Gaffney, Shannon H; McKinley, Meg A; Moody, Emily C; Henshaw, John L; Paustenbach, Dennis J


    Excessive exposures to airborne crystalline silica have been known for over 100 years to pose a serious health hazard. Work practices and regulatory standards advanced as the knowledge of the hazards of crystalline silica evolved. This article presents a comprehensive historical examination of the literature on exposure, health effects, and personal protective equipment related to silica and abrasive blasting operations over the last century. In the early 1900s, increased death rates and prevalence of pulmonary disease were observed in industries that involved dusty operations. Studies of these occupational cohorts served as the basis for the first occupational exposure limits in the 1930s. Early exposure studies in foundries revealed that abrasive blasting operations were particularly hazardous and provided the basis for many of the engineering control and respiratory protection requirements that are still in place today. Studies involving abrasive blasters over the years revealed that engineering controls were often not completely effective at reducing airborne silica concentrations to a safe level; consequently, respiratory protection has always been an important component of protecting workers. During the last 15-20 yr, quantitative exposure-response modeling, experimental animal studies, and in vitro methods were used to better understand the relationship between exposure to silica and disease in the workplace. In light of Occupational Safety and Health Administration efforts to reexamine the protectiveness of the current permissible exposure limit (PEL) for crystalline silica and its focus on protecting workers who are known to still be exposed to silica in the workplace (including abrasive blasters), this state-of-the-science review of one of the most hazardous operations involving crystalline silica should provide useful background to employers, researchers, and regulators interested in the historical evolution of the recognized occupational health hazards

  19. Research on abrasion resistance technique for sinter single-roll crusher%烧结矿单辊破碎机抗磨损技术研究

    陈方述; 聂松辉; 周卓林


    Sinter single-roll crusher is an important component of the sinter production line ,which operating environment and nature decides that it must possess properties of high-temperature resistance and abrasion resistance.First the invalid reasons and abrasive wear mechanism are studied aim at the problems of easy worn and short service life of the single-roll crusher.A conclusion is made that the abrasion pattern is abrasive wear happens under high-temperature environment with forms of chiseling and cutting.Then a structural design with abrasion resistance is studied ,simultaneously its materials selection and hardfacing technics are also analyzed and discussed.Afterwards ,one single-roll crusher with characteristics of long service life and abrasion resistance is designed.which is proved in the engineering practice that the proposed anti-wear technology for single-roll crusher is viable and effective.%单辊破碎机是烧结矿生产线上一个重要的部件,其工作环境与性质决定其必须具有抗高温与耐磨损的特性.针对目前单辊破碎机易磨损、寿命短的问题,首先,对其失效原因与磨损机理等方面进行了研究,得出其主要磨损形式是高温环境下带有凿削形式磨损的磨粒磨损.然后,研究了其抗磨损结构设计的方法,并对其材料选择与耐磨堆焊工艺等进行了详细分析与探讨,设计了一种抗磨损的长寿命烧结矿单辊破碎机.最后,通过工程实际使用验证了提出的单辊破碎枳抗磨损技术是可行且有效的.

  20. Burried MIS 5 abrasion platforms in the Bay of Koper (Gulf of Trieste, Northern Adriatic) confirm long-term subsidence of the Northern Adriatic region

    Trobec, Ana; Šmuc, Andrej; Poglajen, Sašo; Vrabec, Marko


    The youngest seafloor sediments of the Gulf of Trieste (Northern Adriatic) are represented by an up to several 100 meters thick succession of Pliocene to Quaternary continental and shallow-marine deposits recording numerous transgressive-regressive cycles. These sediments are separated from older lithologies (mainly Eocene flysch) by an erosional unconformity. Previous geophysical campaigns conducted in the Italian part of the Gulf of Trieste revealed a complex undulating morphology of the unconformity characterised by numerous morphological steps in the flysch appearing between 40 and 200 m below sea level. From correlation with onshore well data from the Friuli and Veneto area it is assumed that the highest system of these unconformities located at approximately 40 mbsl represents a marine abrasion platform formed during the MIS 5 period sea-level highstand. We present the first observations of these abrasion platforms in the Bay of Koper in the southern (Slovenian) part of the Gulf of Trieste. A series of perpendicular sub-bottom sonar profiles with a spacing of 250-500 meters was acquired in the Bay of Koper between 2009 and 2012 with the Innomar parametric sediment echo sounder SES-2000. Along the northern coast of the bay several acoustic facies were resolved, including the top erosional unconformity surface of the flysch. On this surface we located platforms at 35 ms (platform A), 40 ms (platform B) and 50 ms (platform C) of two-way-travel time. The top of abrasion platform B coincides with the top of a sediment progradational wedge which overlies abrasion platform C. No progradational wedge is developed at the top of platform A. Due to signal attenuation and multiples sub-bottom profiles could not be interpreted below 53 ms TWT time. We used a sound velocity of 1650 m/s for the time to depth conversion, which places the platforms at the depth of 28, 33 and 41 mbsl, respectively. Assuming that the abrasion platforms are a remnant of the MIS 5 highstand, this