간행물
한국분말야금학회지 KCI 등재 Journal of Korean Powder Metallurgy Institute
- 발행기관 한국분말재료학회(구 한국분말야금학회)
- 자료유형 학술지
- 간기 격월간
- ISSN 1225-7591 (Print)2287-8173 (Online)
- 수록기간 1994 ~ 2024
- 주제분류 공학 > 금속공학 공학 분류의 다른 간행물
- 십진분류KDC 559DDC 629
권호리스트/논문검색
Vol. 4 No. 3 (1997년 9월) 9건
1.
1997.09
구독 인증기관 무료, 개인회원 유료
5,400원
2.
1997.09
구독 인증기관 무료, 개인회원 유료
An investigation was performed to apply the M3/2 grade high speed steel for metal injection molding using both prealloyed and elementally blended powders. The injected samples were subjected to a debinding step in gas atmosphere at a ratio that affected the carbon content of the material. The carbon content ranged from 1.4wt.% to 1.43wt%. with increasing content up to 80% in atmosphere for the prealloyed powders. The carbon contents of the elementally blended powders exhibited 1.44wt.% and 1.62wt.% at 10% and 20% gas, respectively. This level decreased to 0.17wt.% upon increasing the content. The sintered density of both powders increased rapidly as the temperature reached the liquid phase forming temperature. After forming the liquid phase, the density rapidly increased to the optimum sintering temperature for the prealloyed powders, whereas the density of mixed elemental powders goes up slowly to the optimum sintering temperature. The optimum sintering temperature and density are 126 and 97.3% for the prealloyed powders and 128 and 96.9% for the elementally blended powders, respectively. The microstructure of the specimen at the optimum sintering temperature consisted of fine grains with primary carbides of MC and type for the prealloyed powders. The elementally blended powders exhibited coarse grains with eutectic carbides of MC, and type.
4,000원
3.
1997.09
구독 인증기관 무료, 개인회원 유료
Milling media of steel and zirconia were used to produce by mechanical alloying (MA) of Mo and Si powders. The effect of milling media on MA of Mo-65.8at%Si powder mixture has been investigated by SEM, XRD, DTh and in-situ thermal analysis. The powders mechanically alloyed by milling medium of steel for 8 hours showed the structure of fine mixture of Mo and Si, and those mechanically alloyed by milling medium of zirconia for longer milling time showed the structure of fine mixture of Mo and Si. The tetragonal - Phase and the tetragonal phase appeared with small Mo peaks in the powders milled by milling medium of steel for 4 and 8 hours. The - phase and the hexagonal - phase were formed after longer milling time. The - phase appeared with large Mo peaks in the powders milled by milling medium of zirconia for 4 hours. The phases, - and -. were formed in the powders milled for longer milling time. DTA and annealing results showed that Mo and Si were transformed into - and , while - into -. In-situ thermal analysis results demonstrated that there were a sudden temperature rise at 212 min and a gradual increase in temperature in case of milling media of steel and zirconia, respectively. The results indicate that MA can be influenced by materials of milling medium which can give either impact energy on powders or thermal energy accumulated in vial.
4,000원
4.
1997.09
구독 인증기관 무료, 개인회원 유료
In most of sintered metal powder compacts, the sintered density distribution is controlled to be as high and uniform as possible to ensure the required mechanical properties. In general, the density distribution in the compacts is not uniform and not easy to measure. In the present study, a method for measuring the density distribution was developed, based on the indentation force equation by which the hardness and the relative density were related. The indentation force equation, expressed as a function of strength constant, workhardening coefficient and relative density, was obtained by finite element analysis of rigid-ball indentation on sintered powder metal compacts. The present method was verified by comparing the predicted density distribution in the sintered Fe-0.5%C-2%Cu compacts with that obtained by experiments, in which the density distribution was directly measured by machining the compacts from the outer surface progressively.
4,000원
5.
1997.09
구독 인증기관 무료, 개인회원 유료
Joining of AIN ceramics to W and Cu by active-metal brazing method was tried with use of (Ag-Cu)-Ti alloy as insert-metal. Joints were produced under various conditions of temperature, holding time and Ti-content in (Ag-Cu) alloy Reaction and microstructural development in bonded interface were investigated through observation and analysis by SEM/EDS, EPMA and XRD. Joint strengths were measured by shear test. Bonded interface consists of two layers: an insert-metal layer of eutectic Ag- and Cu-rich phases and a reaction layer of TiN. Thickness of reaction layer increases with bonding temperature, holding time and Ti-content of insert-metal. It was confirmed that the growth of reaction layer is a diffusion-controlled process. Activation energy for this process was 260 KJ/mol which is lower than that for N diffusion in TiN. Maximum shear strength of 108 MPa and 72 MPa were obtained for AIN/W and AIN/Cu joints, respectively. Relationship between processing variables, joint strength and thickness of reaction layer was also explained.
4,000원
6.
1997.09
구독 인증기관 무료, 개인회원 유료
Mechanical alloying of and added ODS from elemental powders was investigated by the X-ray diffraction, differential scanning calorimeter, transmission electron microscopy and optical microscopy. The steady states of and ODS powders were reached after mechanical alloying with the condition of the ball-to-powder input ratio of 20:1 for 20 hours and 10 hours, respectively. The addition of nano-sized particles enhanced cold working and fracture, and subsequently accelerated MA of powders. DSC results of MAed powders showed four exothermic peaks at 14, 234, 337 and 385. From the high temperature X-ray diffraction analysis, it was concluded that the peaks were resulted from the recovery solution of unalloyed Al in Ni, the formation of intermediate phase NiAl, and ordering of MAed powders.
4,000원
7.
1997.09
구독 인증기관 무료, 개인회원 유료
The densification and grain growth mechanisms of in and in have been investigated. Uranium dioxide powder compacts were sintered at 1 in or at 110 in for various times from 0.5 h to 16 h. The grain size and density of the specimens were measured. From the measured data, the mechanisms of the densification and grain growth were determined by use of available kinetic equations which express the relations between densification and grain growth. In both atmospheres, it has been found that the densification was controlled by the lattice diffusion and the grain growth by the surface diffusion of atoms around pores. It appears that the surface diffusivity as well as the lattice diffusivity increase considerably with the increase in O/U ratio in the specimen.
4,000원
8.
1997.09
구독 인증기관 무료, 개인회원 유료
A P/M high speed steel of ASP 30 grade was austenitized, gas quenched and tempered at various conditional. The mechanical properties such as hardness, bend strength and fracture toughness were evaluated after heat treatment. The microstructure and the type and volume fraction of carbides were analyzed by an optical microscope, image analyzer and XRD. The primary carbides after the heat treatment were MC and type. The volume of the total carbide varied from 10 to 15% depending on the austenitizing and tempering temperature. The tempering temperature for maximum hardness was at around 52. But the maximum bend strength was obtained at about 55. The fracture toughness was largely affected by the presence of retained austenite after gas quenching and secondary hardening during tempering.
4,000원
9.
1997.09
구독 인증기관 무료, 개인회원 유료
4,000원
