• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.627-628
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• 2006

The present work is a study on the argon gas pressure effects of Sinter/HIP sintering on microstructure and strength of different grades of TiC-NiMo cermets. Titanium carbide in the composition of different grades of TiC-NiMo cermets was ranged from 40 to 80 wt.% and the ratio of nickel to molybdenum in the initial powder composition was 1:1, 2:1 and 4:1 respectively. On the sintered alloys, the main strength characteristic, transverse rupture strength (TRS) was measured. Furthermore, the microstructure parameters of some alloys were measured and the pressure effect on pore elimination was evaluated. All the results were compared with common, vacuum sintered alloys. The TRS values of TiC-NiMo cermets could be considerably improved by using Sinter/HIP technique, for high-carbide fraction alloys and for alloys sintered at elevated temperatures.

• Journal of Powder Materials
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• v.13 no.1 s.54
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• pp.10-17
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• 2006

Model experiment was introduced to obtain the formation of a core/rim structure by only liquid phase reaction in Ti(C, N)-based cermet alloys. Infiltrated Ti(C, N)-Ni, $MO_2C-Ni$, and TaC-Ni cermets were bonded to sandwiched specimen by heat treatment $1450^{\circ}C$ for 5hr. With nitrogen addition, both (Ti, Mo) (C, N) and (Ti, Ta) (C, N) rim structure was nucleated around comer of cuboidal Ti(C, N) core. However, equilibrium shapes of(Ti, Mo) (C, N) and (Ti, Ta) (C, N) rim were different possibly due to the effect of interface energy. The core/rim and rim! binder interfaces were parallel to each other with TaC addition, while rotated to each other with $MO_2C$ addition.

• Korean Journal of Materials Research
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• v.12 no.10
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• pp.825-830
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• 2002

The growth rate of solid grains in TiC-XC-2vol% and TiC-XC-30vo1% Ni cermets, where X=Zr, W or Mo, was fitted to an equation of the form $d^3$-$do^3$=Kt. The grain growth behavior during liquid phase sintering at 1673K decreased markedly with addition of $Mo_2$C or WC and increased with addition of ZrC. The contiguity ratio was greater in the alloys with smaller growth rate constant and decreased with increasing Ni content in the $TiC-Mo_2$C-Ni cermet. The grain growth mechanism could be explained by the effect of contiguous grain boundaries in restricting the overall grain growth.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.04a
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• pp.12-12
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• 2004

• Journal of Powder Materials
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• v.6 no.1
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• pp.62-68
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• 1999

The effects of the carbon content ranging from 17.5 to 21.0 wt.% in TiC-30vol.% $Ni_3Al$ cenmet and the $Mo_2C$ content raging from 0 to 30 wt.% in TiC-20 vol.% $Ni_3Al$ cermet were investigated in the relation to the microstures and harbness. The speciment were sintered at 140$0^{\circ}C$, 143$0^{\circ}C$ and 145$0^{\circ}C$ for 60minutes. The results were summarized as follows; 1) The shrinkages and relative densitites of the specimens were incrased up to 20.0 wt.% C and then decreased. 2) The grains of TiC were almost the same size with the different content of carbon. Free carbons were appeared on the microstrures when carbon was added over 20.5 wt.% while TiC and $Ni_3Al$l were formed when carbon was added below 20.0 wt.%; 3) The lattice parameters of the $Ni_3Al$ and TiC phases were increased up to 20.5 wt.% C, and then saturated. 4) The hardess was increased up to 20.0 wt.% C, and then decreased. 5) The $Mo_2C$ made the TiC grains fine and the surrounding structure around TiC gains. 6) The micropores were decreased with increasing the binder and the sintering temperature. 7) The lattice parameter of the $Ni_3Al$l ana TiC were almost the samp up to 10 wt.% $Mo_2C$ and then decreased. 8) The hatdness was increased up to 5wt.% $Mo_2C$ and then decreased owing to the micrpores. 9) The more the binder phase, the higher the relative density and the proper $Mo_2C$ amount of $TiC-Ni_3Al$ cermets were obtained.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.1
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• pp.19-26
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• 2004

The growth of solid particles in TiC-XC-2vo1.% and TiC-XC-30vo1.% Ni alloys, (where X=Zr, W or Mo) was fitted to the equation of the form $d^3$-${do}^3$=Kt during the liquid phase sintering at 1,673K. Also, the grain growth behavior decreased markedly with the addition of ${MO}_2$C or WC and increased with the addition of zrC. The contiguity was greater in the alloys with a smaller growth rate constant and especially, decreased by increasing the Ni content in the TiC-${MO}_2$C-Ni alloy. In addition, the effect of the addition of carbide on the grain growth of 2 vo1.% Ni alloys was found to be similar to that of 30vo1.% Ni alloys. Consequently, the grain growth mechanism cannot be explained by the usual solution / reprecipitation process, but can be explained in terms of a new growth velocity equation, which includes the effects of contiguous carbide grain boundaries in restricting the overall grain growth, as well as the area of the solid / liquid interface in the alloy.