Yuji Katsumura

Sinterability and properties of Ti(N1−x, Ox)y-(V, Ta)C-Ni sintered alloys having a golden colour

The effect of oxygen and carbide addition on the sinterability of TiNy(0.42<y<1)-Ni alloys, in which part of the nitrogen is replaced by oxygen was investigated. It was found that sinterability increased as the oxygen and carbide content increased, but the strength of the resultant sintered alloys was significantly reduced due to the presence of Ni3Ti and Ti2O3 phases when the oxygen content exceeded 50 mol %. The sintered alloy with the highest hardness was found whenx=0.7,y=0.78 and the (V,Ta)C content was 18% by weight and this alloy was characterized by having a low density, good corrosion resistance and the colour of gold.

Effects of TiC Content and Grain Size on Cutting Performance of Al2O3-TiC Ceramic Tools

Al2O3-TiC ceramic tools having 10–50 mass% TiC and different grain sizes were prepared by hot-pressing, and the cutting performance of these toots was studied. The tools having the highest TiC content and the finest TiC grain she showed the largest flank wear (VB) in turning grey cast iron, and the smallest VB in turning ductile cast iron. The tools having 30% TiC content and the finest TiC grain size showed superior resistance to flaking and optimum cutting performance in turning allayed tool steel. Presented at the 45th Annual Meeting In Denver. Colorado May 7–10, 5990

Studies on the Development of Al2O3-SiC Ceramics

At first, oxidation resistance of Al2O3 based ceramics having a single addition of different carbides was investigated, with the result that the ceramics containing SiC in powder(SiC) or whisker(SiC(w)) form showed the highest resistance to oxidation. Attending to this result, the following studies were made. Some properties of Al2O3-SiC ceramics was first studied. Then the improvement of sinterability of this ceramics due to adding SiO2 was studied. Next, cutting performance of Al2O3-SiC ceramics was examined in comparison with the other ceramics tools, and it was made clear that flank wear of Al2O3-SiC tool became larger and smaller than that of Al2O3-TiC tool and Al2O3- SiC(W) one, respectively. Finally, interfacial reaction between Ni and the three sorts of ceramics as above was studied to describe the phenomenon. The outlines of these results were shown.

Improvement of Sinterability of Al2O3-SiC Ceramics

The Al2O3-SiC mixed powder with additional SiO2 powder and pre-oxidized Al2O3-SiC mixed powder containing SiO2 were hot-pressed in Ar. The sinterability of these starting powders were examined comparing with the Al2O3-SiC mixed powder free from SiO2. The structures and transverse-rupture strength (T.R.S.) of hot-pressed ceramics were also examined.It was found that the sinterability of Al2O3-SiC mixed powder was markedly improved with containing over 2-3% SiO2. This was considered to be due to mullite formation and appearance of mullite-SiO2 eutectic liquid during the period of rising temperature to hot-pressing one. With increasing SiO2 contents, the microstructure became locally coagulated and T.R.S. decreased slightly. As the fracture source, an even area of φ70-80 μm, probably due to the coagulated structure, was observed. These results were in detail discussed.