Energy Technology Data Exchange (ETDEWEB)

Further improvement of dimensional tolerance and elimination of such post-processing as cutting work are required for the maximum exhibition of the features of sintered parts. Powder behavior in fall filling and leveling off is observed with the prototype of visual apparatus for observing powder filling. It is found that the delay in the replacement of powder by air in the die and the fall along the angle of repose are the causes for the occurrence of particle size segregation, and that the diagonal downward slide of powder in upper layer only in leveling off is the cause for nonuniformity of the density. As a result, it is found that improvement of powder flowability and minimization of shaking are important for uniform and rapid filling of powder in a thin walled and complicated shape die cavity, and a guide for developing uniform filling method is made clear. Based on the result, a new uniform filling method for powder is under development to improve the flowability of powder. 9 ...

Energy Technology Data Exchange (ETDEWEB)

A geothermal heat pump-assisted heating system is introduced into Changchun City and a survey is conducted to determine if the system may be popularized in this extremely cold region located in the northeastern part of China. In concrete terms, the hot water that circulates through the office building of Changchun Ground Heat Development Co., Ltd., is switched to hot water prepared by a geothermal heat pump. The test continued from December 2000 to March 2001. It is then concluded that heating by geothermal heat pumps will be fully serviceable to Changchun City. Implemented are (1) the shift from the coal fired boiler system to a geothermal heat pump system comprising 16 subterranean heat exchangers for the heating of the office building which is approximately 1000 m{sup 2} large, (2) long-term monitoring of the operating conditions, (3) measurement of subterranean heat exchanger thermal conductivity and subterranean temperature, and (4) the study of pipe shapes for improved thermal ...

Energy Technology Data Exchange (ETDEWEB)

Two kinds of Si3N4/SiC composite ceramics having different sintering auxiliaries were fabricated to investigate reproduction of crack healing phenomenon, effects of sintering auxiliaries on crack healing behavior, optimal crack healing conditions, and high-temperature strength characteristics of crack healed portions. The experiment used sinters added with SiC powder at 20% by volume, and hot-pressed under conditions of a sintering temperature of 1850 degC, time for two hours, and a pressure of 35 MPa. The sintering auxiliaries used are Y2O3 and Al2O3. In the experiment, pre-cracks were introduced into test specimens, and heat treatments were given in atmosphere and in argon gas atmosphere at 1300 degC for one hour. A four-point bending test was conducted in atmosphere as a strength test. The result of the experiment revealed that the materials which were heat-treated in atmosphere have greater crack healing effect, that the optimum heat treatment temperature differs largely according ...

Energy Technology Data Exchange (ETDEWEB)

Pretreatment of brown coal in oil was conducted using 1-methyl naphthalene or mixture of tetralin and 1-methyl naphthalene as solvent at temperatures ranging from 300 to 430{degree}C under nitrogen atmosphere. Effects of the solvent properties on the structural change of oxygen-functional groups (OFG) and coal liquefaction were investigated by means of quantitative analysis of OFG and solid state {sup 13}C-NMR measurement. When hydrogen transfer from solvent was insufficient, it was suggested that brown coal molecules loose their hydrogen to be aromatized. While, at lower temperatures ranging from 300 to 350{degree}C, hydrogen contained in brown coal molecules was consumed for the stabilization of pyrolytic radicals, and the deterioration of liquefaction was not observed. When hydrogen transfer from solvent was insufficient at higher temperatures above 400{degree}C in nitrogen atmosphere during pretreatment in oil, crosslinking like benzofuran type was formed by dehydration ...

Energy Technology Data Exchange (ETDEWEB)

Solubilization of lignite including a large amount of oxygen containing functional groups was attempted using HF/BF3, and the behavior of oxygen containing functional group, one of the important factors for coal liquefaction, was studied. In experiment, the cooled slurry of Yallourn coal specimen and solvent (toluene, isopentane) was filled into a vacuum autoclave together with HF/BF3. Reaction was performed under spontaneous pressure at 50, 100 or 150{degree}C for 3 hours. The distribution of oxygen containing functional groups in each coal specimen was determined by quantification of carboxyl group, hydroxyl group and carbonyl group. As the experimental result, the superacid mixture of HF and BF3 considerably improved the solubility of coal specimens into solvent as compared with individual HF and BF3. The solubility was 68wt% into benzene, 96% into THF and 99% (nearly 100%) into pyridine. It was suggested that production of Broensted acid with strong acidity causes strong catalysis. ...

Energy Technology Data Exchange (ETDEWEB)

It is thought that iron-based catalysts for coal liquefaction exercise their catalytic activity by forming pyrrhotite (Fe(1-x)S). However, there are still a lot of unknown problems remained concerning the formation and agglomeration behaviors of pyrrhotite. These make a difficulty for improving the activity of iron-based catalysts. In this study, sulfiding behaviors of {alpha}-iron oxyhydroxide ({alpha}-FeOOH) and {gamma}-iron oxyhydroxide ({gamma}-FeOOH) were investigated to reveal the formation and agglomeration behaviors of pyrrhotite. It was found that pyrrhotite was easily converted from ferric oxyhydroxide catalysts having large specific surface areas at the sulfiding temperature below 250{degree}C, and fine crystallites of pyrrhotite were formed at the initial stage of sulfiding. Crystal growth of pyrrhotite at the sulfiding temperature over 350{degree}C depended on the catalyst forms. It was also found that smaller crystallites of pyrrhotite were formed from {gamma}-FeOOH than ...

Energy Technology Data Exchange (ETDEWEB)

A unique method, previously proposed by the author, was applied to the heat transfer augmentation in the flow boiling field. In this method a screen sheet was put on the horizontal heated surface where bubble nucleation occurred. Generated vapor bubbles were trapped between the screen and the wall, became flat and moved along the surface. This restricted bubble behavior caused the heat transfer enhancement. Three types of the screen were tested in the present experiment and the effect of the screen was investigated on the heat transfer and two-phase flow characteristics. In two cases of them, the screen was displaced upward by the bubble nucleation. Compared with the ordinary flow boiling case, heat transfer was enhanced by a factor of 1.2 to 6 within the present experimental range. By using a simple flow model, it was made clear that the effect of the height of the displaced screen was important to evaluate the increase in pressure drop. (author)

Energy Technology Data Exchange (ETDEWEB)

It has been clarified by the present authors, based on the plasma nitriding of Fe-Cr alloys and Fe-Ti alloys carried out at the temperature under 550{degree}C hitherto, that an internal nitriding layer is formed due to the fine dispersion of the particles of Cr nitride and Ti nitride in {gamma}{prime} Fe4N layer on the specimen surface. In this study, the plasma nitriding of Fe-Cr alloys are carried out at 650{degree}C, and the effects of the solute (Cr) content on the structures, nitride and the thickness distribution are examined. The main results obtained therefrom are indicated hereafter. In accordance with the observation on the cross-sectional structure of the alloys, only the nitriding layer deduced as the dispersion and precipitation of the particles of Cr nitride from {alpha}-Fe of the mother phase is formed, while {gamma}{prime}-Fe4N layer, which is found at the temperature under 550{degree}C, is not formed. The nitride of Cr generated in the nitriding layer is CrN in all ...

Energy Technology Data Exchange (ETDEWEB)

Austenitic stainless steel castings, such as SCS 13, SCS 14, which consists of {delta}/{gamma} duplex phase, are extensively used as structural material in seawater environments. It is known that SCS 14 involving 2wt% Mo is more resistant to pitting corrosion than SCS 13. In this paper, effects of Mo on the pitting corrosion are discussed in terms of microstructure of the material. The corrosion behavior of the materials with different {delta} ferrite contents and cleanlinesses have been evaluated by seawater exposure testing, electrochemical polarization, and TEM-EDX analysis. The results indicate that pits mainly nucleate at nonmetallic inclusions such as MnS and {delta}/{gamma} boundaries, and materials containing {delta} ferrite above 7vol% have high pitting corrosion resistance. The nucleation at {delta}/{gamma} boundaries is assumed to be due to the segregation of P. It is considered that because of segregation of Mo along {delta}/{gamma} boundaries, SCS 14 is much resistant to ...

Energy Technology Data Exchange (ETDEWEB)

Inert gas contamination, structure and mechanical properties of consolidated high-Ni alloy powder material were studied to improve its characteristics. In experiment, the chemical composition and fraction of porosity in cross sections of Alloy 625 powder were examined which was produced by Ar gas atomization method impinging supplemental gas jet onto accumulated alloy powder in the bottom of a tank for rapid cooling. The structure and mechanical properties of the alloy rod were also examined which was produced by hot hydrostatic pressing or hot extrusion of the powder filled into a capsule. As a result, although Ar content included in the powder produced by Ar gas atomization method decreased with reduction in grain size, the fine powder less than 22{mu}m still included Ar of nearly 0.5mass-ppm. Obvious correlation was found between the fraction of porosity in powder cross sections and Ar in the powder. Although cavities were detected in the consolidated powder material produced by hot ...

Energy Technology Data Exchange (ETDEWEB)

National Research Institute for Materials started in FY1966 a creep data sheet project aiming at obtaining the creep test data until 360Ms (about 11 years and half) in maximum, and has continuously been conducting the above on more than 40 kinds of heat resistant metallic materials for practical use for 30 years already as of January, 1996. The 360Ms creep rupture strength which has been aimed at by this project is the basic important strength property referred to at the time of determining design allowable stress of high temperature structural members. The Institute has published the accumulation of the test data of long range creeps lasting beyond 360Ms of the Institute as a creep data sheet, and in this article, the tremendous volume of this long range creep test data is analyzed and studied systematically, the new knowledge concerning the high temperature strength properties thereby obtained is named the base creep strength concept and explained roughly. The base creep strength ...

Energy Technology Data Exchange (ETDEWEB)

As surface treated steel sheets, steel sheets with Zn-Fe coatings as well as double-layer steel sheets with Fe-P alloy coatings on Zn-Fe alloy coatings are often used practically. Two treatment methods, which are used to dissolve only alloy layers without dissolving steel sheets in order to find amount and composition of alloy layersr have already been reported. This report investigates the mechanisms of these methods, particularly the mechanisms to control dissolution of steel sheets. In the alkali-dissolution method, Zn-Fe alloy coatings are dissolved in a strong alkaline solution(NaOH-triethanolamine (TEA)-H{sub 2}O{sub 2}). In this case, steel sheets are insoluble because passive films are formed on the surface. In the cathodic polarization electrolysis method, alloy layers are electrolyzed({minus}l.2V) and dissolved in an ammonium nitrate-0-phen electrolyte. At this potential, dissolution of steel sheets can be prevented by the 0-phen films adsorbed on the surface. Consequently, ...