Papers by Author: L.J. Zhong

Abstract: A new method is proposed for machinability evaluation of machinable ceramic materials. The relation of machinability attributes is modeled as a digraph, and machinability attribute matrix is defined. Machinability indexes are calculated with permanent function of the matrix, and machinabilities of machinable ceramics are ranked. Five composites consisting of CePO4 and zirconia were fabricated, measured and drilled with tungsten-cobalt carbide bits. Mechanical property parameters of Ce-ZrO2/CePO4 composites, including Vickers hardness, fracture toughness and Elastic modulus, are selected as machinability attributes. The experimental results of material removal rates are consistent with the ranking of machinability index values of Ce-ZrO2/CePO4 ceramics. The machinabilities of Ce-ZrO2/CePO4 ceramics improve with the increase of CePO4 proportions. Machinability of machinable ceramics can be evaluated with digraph method.

Abstract: A new method is proposed for machinability comprehensive evaluation of engineering ceramic materials based on digraph theory. Machinability attributes of the materials are taken as the nodes and the correlations between attributes are taken as the edges. The digraph model for machinability evaluation of ceramics is set up. According to the diagraph model, the machinability attribute matrix was constituted. Then machinability indexes of ceramic materials were calculated with permanent function and machinabilities of the ceramics were evaluated. In this paper, mechanical property parameters of ceramic materials, including hardness, fracture toughness and elastic modulus, were selected as machinability attributes. Machinability of four typical engineering ceramics were evaluated and ranked with machinability indexes. The grinding experiments give further proof of evaluation results.

Abstract: Evaluation system of grindability was proposed for advanced ceramics. Grinding forces and material removals of SiC, Al2O3, Si3N4 and ZrO2 were measured. Grindabilities of ceramics were evaluated with property parameters based on fuzzy comprehensive evaluation theory. The experimental results suggest that grindabilities of SiC and Al2O3 are better than those of Si3N4 and ZrO2. The fuzzy evaluation results show grindabilities of SiC and Al2O3 ceramics are classified as grade of very easy to grind, and Si3N4 and ZrO2 are classified as grade of difficult to grind. The ranking of maximum grinding principal stresses of ceramics considering Poisson’s ratio is SiC, Al2O3, ZrO2 and Si3N4. Theoretical analysis calculated with property parameters is consistent with experimental results in comparison of grinding output parameters. The proposed evaluation system for ceramic grindability is feasible, and the evaluated results are comprehensive and reasonable.