Diamond crystals with low nitrogen concentration were synthesized from the Fe-Ni-C system with Ti additive at high pressure and high temperature (HPHT) in a china-type cubic high pressure apparatus (CHPA). The synthes...Diamond crystals with low nitrogen concentration were synthesized from the Fe-Ni-C system with Ti additive at high pressure and high temperature (HPHT) in a china-type cubic high pressure apparatus (CHPA). The synthesis pressure range was 4.8-5.2 GPa, and the temperature range was 1420-1600 K. The lowest synthesis pressure for diamond fell first and then rose with the increase of Ti additive. The color, shape, surface morphology and nitrogen impurity concentration of the synthesized diamond crystals were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and micro Fourier transform infrared (FTIR) spectrometry. The results show that the Ti additive has significant effects on color, growth rate, crystal shape, surface morphology and nitrogen impurity con- centration of the synthesized diamond crystals. The color of diamond crystals synthesized without Ti additive is yellow, while that with Ti additive becomes light and nearly colorless. The growth rate without Ti additive is higher than that with Ti additive. The crystal shapes of as-grown diamond crystals vary with the increase of Ti additive. The {111} crystal faces become dominant and some {311} crystal faces appear with the increase of Ti additive. The concentration of nitrogen impurity in diamond crystals without Ti additive is higher than that with Ti additive.展开更多
Hot strips of low carbon steels with Ti additive [-contain C 0.04 % -0. 07 % , Si≤0.6%, Mn≤0.6%, Ti 0. 060/00- 0.14% （mass percent）] prodvced by EAF-CSP （Electric Arc Furnaces-Compact Strip Production） process w...Hot strips of low carbon steels with Ti additive [-contain C 0.04 % -0. 07 % , Si≤0.6%, Mn≤0.6%, Ti 0. 060/00- 0.14% （mass percent）] prodvced by EAF-CSP （Electric Arc Furnaces-Compact Strip Production） process were examined by TEM, HREM and XRD. Carbonitrides with different N/C ratio were found in the sam- ples. The varying composition of the Ti-carbonitrides resulted from the supersaturation of Ti and temperature at which the compound was formed. In the tested steel, total mass fraction of the precipitates including cementite, carbonitride and a small quantity of Fe3O4, AO2O3 , Ti2 CS and A1N was about 0. 305 %. XRD results showed that about a quarter of the powder extracted by electrolysis was titanium nitrides, carbonitrides and carbides. Particle arrays formed by interphase precipitation could be observed either in slabs or in hot strips. The dominant reaction mecha- nisms were discussed. Compared with the conventional cold charge process, small amount of Ti addition would be more effective for orecipitation of fine orecioitates in the steels oroduced by CSP process.展开更多
基金Supported by the National Natural Science Foundation of China (Grant Nos. 50572032 and 50731006)
文摘Diamond crystals with low nitrogen concentration were synthesized from the Fe-Ni-C system with Ti additive at high pressure and high temperature (HPHT) in a china-type cubic high pressure apparatus (CHPA). The synthesis pressure range was 4.8-5.2 GPa, and the temperature range was 1420-1600 K. The lowest synthesis pressure for diamond fell first and then rose with the increase of Ti additive. The color, shape, surface morphology and nitrogen impurity concentration of the synthesized diamond crystals were characterized using optical microscopy (OM), scanning electron microscopy (SEM) and micro Fourier transform infrared (FTIR) spectrometry. The results show that the Ti additive has significant effects on color, growth rate, crystal shape, surface morphology and nitrogen impurity con- centration of the synthesized diamond crystals. The color of diamond crystals synthesized without Ti additive is yellow, while that with Ti additive becomes light and nearly colorless. The growth rate without Ti additive is higher than that with Ti additive. The crystal shapes of as-grown diamond crystals vary with the increase of Ti additive. The {111} crystal faces become dominant and some {311} crystal faces appear with the increase of Ti additive. The concentration of nitrogen impurity in diamond crystals without Ti additive is higher than that with Ti additive.
基金Item Sponsored by National Natural Science Foundation of China (50371009)
文摘Hot strips of low carbon steels with Ti additive [-contain C 0.04 % -0. 07 % , Si≤0.6%, Mn≤0.6%, Ti 0. 060/00- 0.14% （mass percent）] prodvced by EAF-CSP （Electric Arc Furnaces-Compact Strip Production） process were examined by TEM, HREM and XRD. Carbonitrides with different N/C ratio were found in the sam- ples. The varying composition of the Ti-carbonitrides resulted from the supersaturation of Ti and temperature at which the compound was formed. In the tested steel, total mass fraction of the precipitates including cementite, carbonitride and a small quantity of Fe3O4, AO2O3 , Ti2 CS and A1N was about 0. 305 %. XRD results showed that about a quarter of the powder extracted by electrolysis was titanium nitrides, carbonitrides and carbides. Particle arrays formed by interphase precipitation could be observed either in slabs or in hot strips. The dominant reaction mecha- nisms were discussed. Compared with the conventional cold charge process, small amount of Ti addition would be more effective for orecipitation of fine orecioitates in the steels oroduced by CSP process.
