Study On Design Theory And Reliability Of Cermet Hard Cladding Parts

Cermet hard cladding parts are new kind of composite parts manufactured by cladding cermet on the substrate with advanced coating technologies. They can be widely used to endure wear and corrosion, fatigue and oxidation, and high temperature. Aimed at the current situation of lacking systemic design theory suitable to these cladding parts, in the paper, based on the study on equivalent properties of the cermet hard cladding material, the design theory under typical service conditions and the reliability of cermet hard cladding parts are deeply investigated, which has established a theoretical base to enlarge the applications of these new parts.The conception of the equivalent elastic modulus of the cermet hard cladding material is proposed. The theoretical models for the relationship between the equivalent elastic modulus and the elastic moduli, the coefficients of thermal expansion of the compositive materials, and the cladding thickness are established. Furthermore, theoretical models of its equivalent Poisson ratio and equivalent shear modulus are also built.Theoretical and experimental researches on equivalent flexural strength of the cermet hard cladding material are carried out on the basis of two conditions of the clad enduring compress and extension actions respectively. Both theoretical model and experimental verification show that the equivalent flexural strength increases with the increase of the cladding thickness. The first failure position locates at the position of the maximum compress stress in the clad for the case of the clad enduring compress action, but it locates at the position of the maximum extension stress in the clad for the case of the clad enduring extension action. A design rule that the compressive strength of the clad material but not the extension strength of the substrate material should be regarded as the design criterion for designing the cladding part based on the equivalent flexural strength in the case of the clad enduring compress action is proposed. The changing laws of the equivalent yield strength, the interface extension strength and the interface shear strength of the cermet hard cladding material with the change of the clad thickness is studied with experiments.Based on the allowed wear quantity, the equivalent maximum shear stress and the interface shear strength under wear condition, the rules for designing cermet hard cladding...