Papers by Keyword: Pulse Plasma Sintering

Abstract: Tungsten carbide (WC) and WCCo powders added with 30 vol.% cubic boron nitride (cBN) and 5 and 12 wt% of Ti were sintered by the pulse plasma sintering (PPS) technique. The sintering process was conducted under a load of 75 MPa at a pressure of 5.10- 5 mbar and a temperature of 1100-1500°C for 5min. The phase composition, density, hardness and microstructure of the sintered material thus obtained were examined. In the cBN-WCTi5wt% composite with an addition of 6wt% Co, the cBN particles are well bound with the matrix. The transcrystalline fractures of the cBN particles also indicate that the binding forces between these particles and the WCCoTi matrix exceed the matrix cohesion. The interfaces between the cBN grains and the surrounding matrix are almost straight lines, and no reactions between the cBN grains and the matrix were revealed in SEM observations.

Abstract: A Pulse Plasma Sintering (PPS) process was employed to manufacture Cu-diamond composites with a 50% volume fraction of each constituent. Pure and Cr (0.8wt.%) alloyed copper matrices were used and commercial diamond powders. The composites were sintered at temperature of 900°C for 20 min and under pressure of 60 MPa. In these sintering conditions diamond becomes thermodynamically unstable. Cu0.8Cr-diamond and Cu-diamond composites with relative densities of 99,7% and 96% respectively were obtained. The thermal conductivity of Cu0.8Cr-diamond composite is equal to 640 W(mK)-1 whereas that of Cu-diamond is 200 W(mK)-1. The high thermal conductivity and relative density of Cu0.8Cr-diamond composite is due to the formation of a thin chromium carbide layer at the Cu-diamond interface.

Abstract: Nanocrystalline WC-12wt.%Co was consolidated by Pulse Plasma Sintering (PPS) at various temperatures between 900 and 1200oC for 6 minutes under a pressure of 60MPa. Cemented carbides sintered at 1100oC have a relative density of 99%, a hardness of 2248HV30, the fracture toughness, KIC=12.5 MPa*m1/2, and have a structure containing 50nm WC crystallites. Increasing the sintering temperature to 1200oC causes an increase in the size of the WC crystallite size to about 110 nm, reduces the hardness to 2198HV30, and decreases the KIC to 9.7 MPa*m1/2.

Abstract: The paper presents the results of examination of the structure and properties of nanocrystalline Cu-Al2O3 composites with the two different Al2O3 contents: 10 and 20 vol.%. The composites were produced using a mixture of copper and Al2O3 powders with an average crystallite size of about 60nm for Cu and about 40nm for Al2O3. The powders were consolidated by pulse plasma sintering (PPS) for 5 minutes at a temperature of 650oC under a load of 60 MPa. Irrespective of the volumetric content of Al2O3, the relative density of the composites was about 92%, and the average Cu crystallite size was about 80nm. The hardness of the composites varied with the volumetric content of Al2O3, and was equal to 270 HV0.1 for 20 and to 240 HV0.1 for 10% of Al2O3. The Cu-20%Al2O3 composite had a resistivity of 0.386 while that with 10% of Al2O3 was 0.149 56m.