Firstly,the relation between the coefficient of thermal expansion(CTE)and the volume fraction of TiO_(2) was investigated, and also the influence of relative density of ceramic on the CTE was studied.The results show ...Firstly,the relation between the coefficient of thermal expansion(CTE)and the volume fraction of TiO_(2) was investigated, and also the influence of relative density of ceramic on the CTE was studied.The results show that the volume fraction of TiO_(2) and the relative density both make influence on the CTE of ZrO_(2)-TiO_(2) ceramic.According to the results,the ZrO_(2)-TiO_(2)(volume fraction of TiO_(2) is 27%)ceramic die with the similar CTE(8.92×10^(-6) ℃^(-1))to Ti6Al4V was fabricated.Secondly,to evaluate the dimensional accuracy of the workpiece superplastically formed,the Ti6Al4V impression experiment was performed.The result shows that the dimensional inaccuracy of workpiece is 0.003.Thirdly,in order to evaluate the practicability,the experiment of superplastic forming Ti6Al4V using ZrO_(2)-TiO_(2) cylinder ceramic die was carried out.The Ti6Al4V cylinder shows good shape retention and surface quality,and high dimensional accuracy.The ceramic dies seem to be adequate for superplastic forming the high accuracy Ti6Al4V, and the trials have confirmed the potential of the ZrO_(2)-TiO_(2) ceramic die.展开更多
Development and application of new ceramic die materials is one of the important topics in the field of die research. The composition, processing technology, mechanical property and engineering performance of the cera...Development and application of new ceramic die materials is one of the important topics in the field of die research. The composition, processing technology, mechanical property and engineering performance of the ceramic materials such as cermet, ZTA, TZP, TZP/Al2O3, TZP/TiC/Al2O3, PSZ and Sialon, etc., with rare earth yttrium, lanthanum and cerium, and so on working as additives, were investigated and analyzed in the present study. Problems existed in the research and application of rare earth ceramic die materials were discussed. Rare earth additives can effectively improve the mechanical property and engineering performance of ceramic die materials. Thus, it will have further perspectives of wider application. More attention should be paid in the future to the toughening and strengthening of the ceramic die materials, the adding forms and kinds of rare earth elements and acting mechanisms of rare earth additives in ceramic die materials.展开更多
Wear resistance of several zirconia toughened ceramics in comparison with a metal-ceramic Co-WC has been studied in drawing wire field test. Result indicates that the harder the ceramic die, the longer the service lif...Wear resistance of several zirconia toughened ceramics in comparison with a metal-ceramic Co-WC has been studied in drawing wire field test. Result indicates that the harder the ceramic die, the longer the service life. Excellent wear resistance of ceramic die is obtained with a very high hardness (19 GPa). The service life is nearly three times that of Co-WC die. SEM observation on wear surfaces showed that material removal is mainly caused by plastic flow and ploughing process. But when the ceramic is composed of zirconia, alumina and some titanium carbide, micro-chipping and tribochemical reaction take place, and wear rate increases. Wear and friction induced martensite was detected by XRD. The T-M (tetragonal to monoclinic) phase transformation has a contribution to inhibiting microfracture.展开更多
文摘Firstly,the relation between the coefficient of thermal expansion(CTE)and the volume fraction of TiO_(2) was investigated, and also the influence of relative density of ceramic on the CTE was studied.The results show that the volume fraction of TiO_(2) and the relative density both make influence on the CTE of ZrO_(2)-TiO_(2) ceramic.According to the results,the ZrO_(2)-TiO_(2)(volume fraction of TiO_(2) is 27%)ceramic die with the similar CTE(8.92×10^(-6) ℃^(-1))to Ti6Al4V was fabricated.Secondly,to evaluate the dimensional accuracy of the workpiece superplastically formed,the Ti6Al4V impression experiment was performed.The result shows that the dimensional inaccuracy of workpiece is 0.003.Thirdly,in order to evaluate the practicability,the experiment of superplastic forming Ti6Al4V using ZrO_(2)-TiO_(2) cylinder ceramic die was carried out.The Ti6Al4V cylinder shows good shape retention and surface quality,and high dimensional accuracy.The ceramic dies seem to be adequate for superplastic forming the high accuracy Ti6Al4V, and the trials have confirmed the potential of the ZrO_(2)-TiO_(2) ceramic die.
基金Project supported by National Natural Science Foundation of China (50405047)Natural Science foundation of Shandong Province (Y2005F04)Jinan Young Star Plan of Science and Technology (08108)
文摘Development and application of new ceramic die materials is one of the important topics in the field of die research. The composition, processing technology, mechanical property and engineering performance of the ceramic materials such as cermet, ZTA, TZP, TZP/Al2O3, TZP/TiC/Al2O3, PSZ and Sialon, etc., with rare earth yttrium, lanthanum and cerium, and so on working as additives, were investigated and analyzed in the present study. Problems existed in the research and application of rare earth ceramic die materials were discussed. Rare earth additives can effectively improve the mechanical property and engineering performance of ceramic die materials. Thus, it will have further perspectives of wider application. More attention should be paid in the future to the toughening and strengthening of the ceramic die materials, the adding forms and kinds of rare earth elements and acting mechanisms of rare earth additives in ceramic die materials.
文摘Wear resistance of several zirconia toughened ceramics in comparison with a metal-ceramic Co-WC has been studied in drawing wire field test. Result indicates that the harder the ceramic die, the longer the service life. Excellent wear resistance of ceramic die is obtained with a very high hardness (19 GPa). The service life is nearly three times that of Co-WC die. SEM observation on wear surfaces showed that material removal is mainly caused by plastic flow and ploughing process. But when the ceramic is composed of zirconia, alumina and some titanium carbide, micro-chipping and tribochemical reaction take place, and wear rate increases. Wear and friction induced martensite was detected by XRD. The T-M (tetragonal to monoclinic) phase transformation has a contribution to inhibiting microfracture.
