Huang Chuanzhen

An analysis of unsteady thermal stresses in a functionally gradient ceramic plate with symmetrical structure

Abstract The analytical formulae of one-dimensional unsteady temperature field and unsteady thermal stress field for a functionally gradient material plate with symmetrical structure were derived by using perturbation method, by which the unsteady temperature fields and unsteady thermal stress fields of an Al2O3/(W,Ti)C functionally gradient ceramic plate with symmetrical structure were calculated in case of both surface cooling and surface heating. The results obtained showed that the absolute values of thermal stresses of the functionally gradient ceramic plate are lower than those of the homogeneous ceramic plate for both surface cooling and surface heating cases. Hence an approach to improving the thermal shock resistance of ceramic tool materials i.e. using functionally gradient ceramic tool materials, was put forward and verified by intermittent turning of hardened tool steel.

A study on the wear resistance of ZrO2/Al2O3 ceramic scissors for spinning and weaving

A new kind of zirconia matrix ceramic material (ZrO2/Al2O3) has been developed with 3Y-PSZ (3 mol% Y2O3 partially stabilized ZrO2) and the additive of alumina. The wear resistance of ZYA20 (3Y-PSZ+20 wt.% Al2O3) has been experimentally investigated compared with ZYA30 (3Y-PSZ+30 wt.% Al2O3) by the wear ring-block test. It is shown that the friction coefficients of ZYA20 and ZYA30 decrease with the increment of the applied load and the wear ratios increase with the increment of the applied load. It is also found that their wear mechanisms are plastic deformation, adhesive and abrasive wear, as well as stripping. The wear resistance of ZYA20 and ZYA30 are very good at low load and ZYA20 is stronger than ZYA30.

Simulation design for the composition of zirconia composite ceramic tool

The relationship between the fracture toughness increment (ΔKIC) resulting from toughening mechanisms, such as phase transition, residual stress, geometry effect, and grain bridging, and the volume fraction of zirconia was established to simulate and design the composition of a zirconia-matrix composite tool, thereby avoiding “trial-and-error” experiments. The composition of the ZrO2/Al2O3 ceramic tool was simulated in accordance with the requirement for fracture toughness. It was shown that the simulated result was in agreement with experiment and that the established simulation model was to some extent valid in predicting the composition of the zirconia-matrix composite ceramic tool with dispersed α-Al2O3. Thus, a new type of ceramic tool material, a ZrO2/Al2O3 composite, was developed by adding α-Al2O3 to ZrO2 on the basis of the results of the computer simulation.