To improve coating ability and the life of the coating, Ti based composite materials with hydroxyapatite(HA) should be developed. The raw materials of Ti-26wt%, Nb-1wt%, and Si with 10wt% HA were mixed for 24 h by a mixing machine and milled for 1 h to 6 h by planetary mechanical ball milling. Ti-26%Nb-1%Si-(10%HA) composites, composed of nontoxic elements, were fabricated successfully by spark plasma sintering(SPS) at 1000˚C under 70MPa. The relative density of the sintered Ti-Nb-Si-HA composites using the 24 h mixed powder, and the 6 h milled powder, was 91% and 97 %, respectively. The effects of HA contents and milling time on microstructure and mechanical properties were investigated by SEM and hardness tester, respectively. The Vickers hardness of the composites increased with increasing milling time and higher HA content. The Young's modulus of the sintered Ti-26%Nb-1%Si-10%HA composite using the 6 h-milled powder was 55.6 GPa, as obtained by compression test. Corrosion resistance of the Ti-26wt%Nb-1wt%Si composite was increased by milling and by the addition of 10wt%HA. Wear resistance was improved with increasing milling time. Biocompatibility of the Ti-Nb-Si alloys was improved by the addition of HA.

Powder metallurgy applied rapid heating to sintering starting year 1900. Since 1970 the study has intensified. Now rapid sintering concepts embrace a spectrum of options ranging from dunk cycles to microwave, induction, exothermic, electric field, and spark approaches. Most of the efforts are targeting reduced microstructure coarsening during sintering, although reduced material decomposition is another common goal. The efforts are impressive for simple shapes and success metrics such a small grain size after densification. Several barriers need to be removed prior to application in powder metallurgy commercial sintering. Rapid heating research needs to focus on significant property gains, accurate product dimensions, and lower costs. So far each property gain obtained with rapid heating is matched by traditional sintering and composition changes. Several examples are cited to show the goals for the next round of innovations.

Ti-6Al-4V ELI (Extra Low Interstitial) alloy have been widely used as alternative to bone due to its excellent biocompatibility, although it still has many problems such as high elastic modulus and toxicity. Therefore, biomaterials with low elastic modulus and non toxic characteristics have to be developed. A novel β Ti-35wt%Nb-7wt%Zr-Calcium pyrophosphate (CPP) composite that is a biocompatible alloy without elemental Al or V was fabricated by spark plasma sintering (SPS) at 1000˚C under 70 MPa using high energy mechanical milled (HEMM) powder. The microstructure and phases of the milled powders and the sintered specimens were studied using SEM, TEM, and XRD. Ti-35wt%Nb-7wt%Zr alloy was transformed from α phase to β phase in the 4h-milled powder by sintering. The sintered specimen using the 4h-milled powder showed that all the elements were distributed very homogeneously and had higher density and hardness. β Ti alloy-CPP composite, which has nanometer particles, was fabricated by SPS using HEMMed powder. During the sintering process, CaTiO3, TixOy, and CaO were formed because of the reaction between Ti and CPP. The Vickers hardness of the composites increases with the increase of the milling time and the addition of CPP. The biocompatibility of the Ti-Nb-Zr alloys was improved by addition of CPP.

Ti-6Al-4V ELI (Extra Low Interstitial) alloy has been widely used as an alternative to bone due to its excellent biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity. Therefore, nontoxic biomaterials with a low elastic modulus should be developed. However, the fabrication of a uniform coating is challenging. Moreover, the coating layer on Ti and Ti alloy substrates can be peeled off after implantation. To overcome these problems, it is necessary to produce bulk Ti and Ti alloy with hydroxyapatite (HA) composites. In this study, Ti, Nb, and Zr powders, which are biocompatible elements, were milled in a mixing machine (24h) and by planetary mechanical ball milling (1h, 4h, and 6h), respectively. Ti-35%Nb-7%Zr and Ti-35%Nb-7%Zr-10%HA composites were fabricated by spark plasma sintering (SPS) at 1000˚C under 70MPa using mixed and milled powders. The effects of HA addition and milling time on the biocompatibility and physical and mechanical properties of the Ti-35%Nb-7%Zr-(10%HA) alloys have been investigated. Ti2O, CaO, CaTiO3, and TixPy phases were formed by chemical reaction during sintering. Vickers hardness of the sintered composites increases with increased milling time and by the addition of HA. The biocompatibilty of the HA added Ti-Nb-Zr alloys was improved, but the sintering ability was decreased.

The p-type thermoelectric compounds of based doped with 3wt% Te were fabricated by a combination of rapid solidification and spark plasma sintering (SPS) process. The effect of holding time during spark plasma sintering (SPS) on the microstructure and thermoelectric properties were investigated using scanning electron microscope (SEM), X-ray diffraction (XRD) and thermoelectric properties. The powders as solidified consisted of homogeneous thermoelectric phases. The thermoelectric figure of merit measured to be maximum () at the SPS temperature of .

A new High Frequency Induction Heating (HFIH) process has been developed to fabricate dense reinforced with Fe-Ni magnetic metal dispersion particles. The process is based on the reduction of metal oxide particles immediately prior to sintering. The synthesized /Fe-Ni nanocomposite powders were formed directly from the selective reduction of metal oxide powders, such as NiO and . Dense /Fe-Ni nanocomposite was fabricated using the HFIH method with an extremely high heating rate of . Phase identification and microstructure of nanocomposite powders and sintered specimens were determined by X-ray diffraction and SEM and TEM, respectively. Vickers hardness experiment were performed to investigate the mechanical properties of the /Fe-Ni nanocomposite.

A new approach to sintering loose packed, coarse aluminum alloy powder to full or near full density is presented. A controlled amount of water vapor is introduced into the sintering atmosphere, which disru pts the oxide film and allows metallurgical contact between particles. In addition, supersolidus liquid phase sintering is used to sinter the part to full density. Since the method is particularly applicable to uncompacted powders, it is potentially useful for sintering aluminum powder preforms manufactured by 3DPrinting and powder injection molding.

새로운 급속소결방법인 고주파유도가열 소결법과 펄스전류활성 소결법을 이용하여 습식 볼밀링으로 혼합한 WC-8wt.%Co분말에 60MPa의 압력과 90%의 고주파출력 또는 2800A의 필스전류를 가하여 상대밀도가 98.6% 이상인 초경재료를 2분이내의 짧은 시간에 제조하였다. 초기의 WC분말의 입도가 미세해짐에 따라 고주파유도가열 소결법과 펄스전류활성 소결법 모두 소결시간이 단축되는 경향을 보였으며 그 소결체의 결정립 크기도 감소하였다. 고주파유도가열 소결

급속소결방법인 고주파유도가열 소결법과 펄스전류활성 소결법을 이용하여 습식 볼밀링으로 혼합한 WC-8wt.%Ni분말에 60MPa의 압력과 고주파유도가열장치의 경우 전체 용량 (15kw)의 90%에 해당하는 고주파출력을, 펄스전류활성 소결장치의 경우 2800A의 펄스전류를 가하여 치밀한 소결체를 2분이내의 짧은 시간에 제조하였다. WC 초기입자크기가 증가함에 따라 제조된 소결체의 입자크기와 평균자유행로는 증가하였다. 또한 WC 결정립 크기가 증가함에 따라

Using the nano Fe powders having 50 nm in diameter, Fe compact bodies were fabricated by injec-tion molding process. The relationship between microstructure and material properties depending on the volume ratio of powder/binder and sintering temperature were characterized by SEM, TEM techniques. In the compact body with the volume percentage ratio of 45(Fe powder) : 55(binder), which was sintered at the relative density was about and the values of volume shrinkage and hardness were about and 242.0 Hv, respec-tively. Using the composition of 50(Fe powder) : 50(binder) and sintered at the values of relative density, volume shrinkage and hardness of Fe sintered bodies were and 152.8 Hv, respectively. They showed brittle fracture mode due to the porous and fine microstructure.

(1) Using high-frequency induction heating sintering and spark plasma sintering method, the densification of WC-Ni hard materials was accomplished using ultra fine power of Ni and WC. (2) Nearly fully dense WC-Ni could be obtained within 1 min. (3) Relative density and mechanical properties of WC-Ni obtained by HFIHS were high than those obtained by SPS. And WC grain size made by HFIHS was smaller than that made by SPS. (4) The fracture toughness and hardness values of WC-8Ni, WC-10Ni, and WC-12Ni made by HFIHS were , respectively for 60MPa and an induced current for 90% output of total capacity, 15KW. (5) The fracture toughness and hardness values of WC-8Ni, WC-10Ni, and WC-12Ni made by SPS were , respectively for 60MPa and the electric current of 2500 A

1) Using a developed high-frequency induction heated sintering method, the rapid densification of WC-Co hard materials was accomplished using ultra fine powders with 260 nm size within 1 minute. 2) The relative density of the composite was 99.5% for the applide pressure of 60MPa and the induced current for 90% output of total capacity. 3) The grain size of WC-Co hard materials is about 260nm and the average thickness of the binder phase determined is about 11nm. The fracture toughness and the hardness of this work 12 , respectively. 4) Using pressureless sintering, we produced dense WC-Co hard materials with a relative density of 97% without applying pressure.