간행물
한국분말야금학회 학술대회논문집
- 발행기관 한국분말재료학회(구 한국분말야금학회)
- 자료유형 학술대회
- 간기 부정기
- 수록기간 1993 ~ 2006
- 주제분류 공학 > 금속공학 공학 분류의 다른 간행물
- 십진분류KDC 559DDC 629
권호리스트/논문검색
한국분말야금학회 2006년도 춘계학술대회논문집 (2006년 4월) 443건
221.
2006.04
구독 인증기관·개인회원 무료
Using as sintering additives and Si as a raw powder, the continuously porous in-situ bodies were fabricated by multi-pass extrusion process and their microstructures were investigated depending on the addition of carbon (0-9wt%) in the mixture powder. The introduction of fibers observed in the unidirectional continuous pores as well as in the pore-frame regions of the nitrided bodies can be an effective method in increasing the filtration efficiency. In the case of no carbon addition, the network type fibers with high aspect ratio appeared in the continuous pores with diameters of 150-200 nm. However, in the case of 9wt% C addition, the fibers were found without any network type and had diameters of 200-250 nm.
222.
2006.04
구독 인증기관·개인회원 무료
We have demonstrated that textured nanocomposites can be fabricated by slip casting followed by partial oxidation - reaction sintering of mixed suspensions of and SiC powders in a high magnetic field. The sintered density was changed by the degree of oxidation at 1200C and 1300C. The degree of orientation of alumina in the nanocomposite was examined on the basis of the X-ray diffraction patterns and scanning electron micrographs. It is confirmed that alumina-oriented nanocomposites were fabricated. The three-point bending strength at room temperature was observed for the nanocomposites.
223.
2006.04
구독 인증기관·개인회원 무료
224.
2006.04
구독 인증기관·개인회원 무료
Fabrication of a nano-laminar ceramic composite by sintering thin ceramic plates was examined. Silver-coated glass flakes with a thickness of less than were consolidated by pulsed current sintering or hotpressing to obtain model composites. The samples sintered at the optimum conditions were fairly dense, and the flakes were aligned by uniaxial press. The metal coating remained on the flakes through the sintering process, and became an interface layer between the flakes. No crack propagation through the transverse direction of the lamellar was observed in the indentation test. The possibilities of high resistance against crack propagation was suggested.
225.
2006.04
구독 인증기관·개인회원 무료
The driving forces and the probable processes of WC-Co grain growth are reanalysed from recent data of interface energy and microstructure. Grain growth is driven by the disappearing of the high energy WC/WC and WC/Co interfaces with habit planes different from {0001}, and facets and by the area decrease of the WC/WC and WC/Co interfaces with {0001} and habit planes. Grain growth mainly results of dissolution-precipitation. Abnormal grains are likely formed by defects assisted nucleation.
226.
2006.04
구독 인증기관·개인회원 무료
WC/WC interface in VC mono-doped WC-10mass%Co submicro-grained hardmetals of was investigated together with WC/Co interface by using HRTEM and XMA. The thickness of V-rich layer and the analytical value of V at WC/WC interface were almost the same as those at WC/Co interfaces. These results, etc., suggested that the V-rich layers at both interfaces were not generated by an equilibrium segregation mechanism in the sintering stage, but generated by a preferential precipitation mechanism during the solidification of Co liquid phase in the cooling stage. Based on this suggestion, we succeeded in developing a nano-grained hardmetal with 100 nm .
227.
2006.04
구독 인증기관·개인회원 무료
During sintering of cemented carbides abnormal grain growth is often observed but cannot be understood from the classical LSW-theory. A model based on 2-D nucleation of new crystalline layers and a grain-size distribution function is formulated and the equations are solved numerically. Experimental studies and computer simulations show that the initial grain size distribution has a strong effect on the grain growth behavior. For example, a fine-grained powder can grow past a coarser powder.
228.
2006.04
구독 인증기관·개인회원 무료
The solubility of Cr in cubic carbides in the systems WC-Co-TaC and WC-Co-ZrC has been determined using equilibrium samples. Thermodynamic calculations were used to design the alloys through extrapolations of Gibbs energy expressions. The alloys were designed to have a microstructure containing the following phases: WC, liquid, , graphite and cubic carbide. The alloys were investigated using scanning electron microscopy and analyzed using energy-dispersive X-ray spectrometry. The present work shows how the Cr solubility depends on which cubic carbide former that is present. The WC-Co-Cr-Zr alloy has no detectable amount of Cr whereas the WC-Co-Cr-Ta alloy has 12% Cr in the cubic carbide.
229.
2006.04
구독 인증기관·개인회원 무료
High functional micro devices are demanded in a variety of fields. For realising such demands, development of high-precision micro-components installed in the devices are needed. To achieve high-precision in the mold processing of micro-components, the development of mold materials, i.e., the development of WC-Co hardmetal with higher hardness and fracture strength is essential, together with the developments of processing technology of high precision mold and mold-forming technology of high precision micro-components, etc. The role of development of the finer submicro-grained hardmetal in a NEDO national project aiming the integrated development of these all technologies and some results are mainly explained.
230.
2006.04
구독 인증기관·개인회원 무료
In order to develop the nano-sized WC powder that improved the hardness of hardmetals, carbothermal reduction of WO3 by C was examined by using the thermogravimetric analysis. At the direct carburization reaction path of , the nano-sized grain was generated at the reaction stage to and W. For trial production, the intermediate products which consists of metal and carbide phases obtained by the first heating has been carburized to the final WC powder. We succeeded in the development of the WC powder of about 70nm. In addition, the nano-sized WC powder in which the vanadium of the most effective grain growth inhibitor was uniformly dispersed was developed.
231.
2006.04
구독 인증기관·개인회원 무료
The linear intercept (LI) method was used to quantitatively measure the intercepts of WC grains in nano-grained WC-10Co hardmetal. When the surveyed intercept numbers of WC grain exceeded 200, the statistic data for the mean grain size of WC were reproduced. The discriminative minimal grain size of used LI method was 12 nm; the maximum intercept of WC grain was 109 nm; the average intercept of WC grains was 45 nm and the corresponding 3D mean grain size of WC was 70 nm which is agreeable with the XRD outcome.
232.
2006.04
구독 인증기관·개인회원 무료
New manufacturing processes, such as thermochemical, mechanochemical and chemical vapor condensation processes have been developed to obtain nanostructured WC/Co materials. Nanoscale size WC/Co composite powders of near 100-150nm can be synthesizes by thermochemical and mechanochemical processes using water soluble precursors. Non-agglomerated and nano sized WC powder can be synthesized by the chemical vapor condensation process using metallorganic precursors as starting materials. In this paper, the scientific and technical issues on synthesis and consolidation of nanostructured WC/Co alloys produced by new chemical processes are introduced.
233.
2006.04
구독 인증기관·개인회원 무료
The plastic deformation behavior of cemented carbides is related to the WC grain boundary strength. Ab initio calculations predict that Co and Mn segregate to WC/WC grain boundaries. To experimentally study the effect of Mn, a WC-Co-Mn material was manufactured and compared to a WC-Co material. The microstructure was studied using scanning electron microscopy (SEM), including electron backscatter diffraction (EBSD). Special attention was paid to the WC grain size and the frequency of special low-energy grain boundaries. Mn was found to have negligible effect on both the WC grain growth and the fraction of WC/WC boundaries in the as-sintered material.
234.
2006.04
구독 인증기관·개인회원 무료
A solid stage sinterizacion model of the WC-Co is applied on this work. These results are compaired with the experimental data obtained for nanometric and micrometric sinter powder in an electric furnace and micrometric in a plasma reactor (using Abnormal Glow Discharge AGD). The correlations obtained allow the prediction of the sintering behavior in AGD for nanometric powder. The activation of the solid state sintering is shown with the decraease of the WC size and the use of AGD
235.
2006.04
구독 인증기관·개인회원 무료
The effect of TiC content on oxidation behavior of the sintered WC-TiC-TaC alloys with 2 mass% TaC and different TiC amounts of 3-45 mass% was investigated through oxidation tests in air at 973K. As a result of the tests, it was revealed that with increasing TiC content in the alloys, mass changes caused by oxidation and thickness of the scale decreased. Thus, it is considered that the main component of the scales changed gradually from to with increasing TiC content in the alloys, and oxygen diffusion through the scale to the alloys was inhibited gradually.
236.
2006.04
구독 인증기관·개인회원 무료
237.
2006.04
구독 인증기관·개인회원 무료
Uchiyama, Yasuo, Ueno, Shuji, Sano, Hideaki, Tanaka, Hiroki, Nakahara, Kenji, Sakaguchi, Shigeya, Nakano, Osamu
WC-TiC-TaC binderless cemented carbide was oxidized under low partial pressure of oxygen (50ppm) at 873K for 1 to 20 h. Surface roughness was measured using atomic force microscope, and effect of TiC amount on oxidation behavior of the carbide was investigated. WC phase was oxidized more easily than WC-TiC-TaC solid solution phase. With an increase in TiC amount, WC-TiC-TaC phase increased and the oxidation resistance of the carbide increased.
238.
2006.04
구독 인증기관·개인회원 무료
239.
2006.04
구독 인증기관·개인회원 무료
Ru-C nano-composite films were prepared by MOCVD, and their microstructures and their electrode properties for oxygen gas sensors were investigated. Deposited films contained Ru particles of 5-20 nm in diameter dispersed in amorphous C matrix. The AC conductivities associating to the interface charge transfer between Ru-C composite electrode and YSZ electrolyte were 100-1000 times higher than that of conventional paste-Pt electrodes. The emf values of the oxygen gas concentration cell constructed from the nano-composite electrodes and YSZ electrolyte showed the Nernstian theoretical values at low temperatures around 500 K. The response time of the concentration cell was 900 s at 500 K.
240.
2006.04
구독 인증기관·개인회원 무료
Nanostructured aluminum powders were obtained by means of planetary ball milling with methanol as the Process Control Agent (PCA). The behavior, during milling, was considered measuring the microhardness and grain size at different milling times. Bulk near-full density samples were sintered using the Spark Plasma Sintering technology with different schedules: temperature of and , pressure of 30 MPa and 60 MPa and different modes of applying the pressure were changed in order to understand the behavior during sintering. All the samples retained their nanostructure with an increase of the grain size from about 46 up to 70-90 nm.
