Papers by Author: Lian Yong Xu

Abstract: The non-cyanide silver electroplating on copper substrate has been discussed. Based on the surface morphology by using SEM, the smooth and fine silver layer is obtained. The influences of concentration of silver and plating temperature on the thickness of the plating layer are discussed, the thickness of the silver layer is increasing with silver concentration rising and plating temperature rising.

Abstract: In the present study, the residual stress generated in the crack tip of compact specimens was investigated in order to analyze the effect of residual stress on the creep crack growth. Residual stresses were generated using loading in compression beyond yield and then unloading. The maximum region of residual stress in the crack tip was obtained by numerical simulations which calculated the effect of notch radius and penetrated stress. It was found that a 2.5 mm notch radius with the applied stress at 36 KN could generate the largest extent of residual stress ahead of crack tip in the compact specimen. Further, when the specimen was heated to a high temperature, the value of residual stress reduced while the distribution changed little.

Abstract: In this paper, the local approach was used to analyze the geometry dependence of coating specimens for interface brittle fracture initiation, and a definition of the fracture process zone was proposed in the paper. The results showed that the interface fracture behavior of two types of specimens with notch had been predicted from the test results of pre-crack specimens based on the local approach for interface brittle fracture, and the predicted distribution of the critical load for the notched specimens gave a good agreement with the test results. It indicated that the local approach not only can be used to describe the interface fracture behavior, but also can be used in the integrity evaluation for interface between different materials.

Abstract: In this paper, the local approach based on the Weibull stress criterion was used to investigate the interfacial fracture behavior between LX88A coating and Q345 steel. LX88A coating was deposited by high velocity electric arc spraying technology (HVAS). The finite element method (FEM) was used to analyze the stress-strain fields of the coating specimen which consisted of three different specimen geometrics or modes of loading. It was found that the Weibull stress for all specimen geometries was almost identical under the same fracture probability when the interfacial fracture initiation occurred for different specimen geometries. It showed that the geometry dependence on the interface brittle fracture toughness data can be reduced through application of the local approach, and the local approach can be used to describe the interfacial fracture behavior.