【作者】 杨俊茹；

【导师】 李兆前；

【作者基本信息】 山东大学 ， 机械制造及其自动化， 2006， 博士

【摘要】 金属陶瓷硬质覆层零件是利用先进涂覆层技术在基体零件上涂覆金属陶瓷硬质覆层而得到的新型层状复合材料零件，可广泛应用于耐磨抗蚀、耐疲劳抗氧化及耐高温场合。针对目前缺乏系统的适应于金属陶瓷硬质覆层零件设计理论的现状，本文在对金属陶瓷硬质覆层材料等效性能研究的基础上，对覆层零件在典型服役条件下的设计理论及其可靠性进行了系统研究，为进一步扩大该新型覆层零件的应用领域奠定了理论基础。 提出了金属陶瓷硬质覆层材料的等效弹性模量的概念，建立了其等效弹性模量与组成材料弹性模量、热膨胀系数、覆层厚度等参数之间的理论关系模型，并进行了实验研究。建立了金属陶瓷硬质覆层材料等效泊松比和等效剪切模量理论模型。 建立了覆层受压和受拉两种作用方式下金属陶瓷硬质覆层材料的等效抗弯强度理论模型，并进行了实验研究。结果表明，材料的等效抗弯强度随着覆层厚度的增加而增加；覆层受压时，材料首先在硬质覆层的最大压应力点发生破坏，而覆层受拉时，材料首先在硬质覆层的最大拉应力点发生破坏。针对覆层受压，提出了基于等效抗弯强度进行硬质覆层零件设计时，应该以覆层部分材料的抗压强度而不是以基体材料的抗拉强度为设计准则。对金属陶瓷硬质覆层材料的等效屈服强度、界面拉伸强度和界面剪切强度随覆层厚度的变化规律进行了实验研究。 提出了磨损载荷作用下金属陶瓷硬质覆层零件的设计准则，即基于允许磨损量、等效最大剪切应力和界面剪切强度的设计准则。建立了覆层零件磨损量、等效最大剪切应力以及界面最大剪切应力理论模型，并进行了实例和有限元研究。结果表明，当零件总厚度不变时，硬质覆层零件的等效最大剪切应力和界面最大剪切应力均随着覆层厚度的增大而减小、随着磨损载荷的增大而增大、并与摩擦副材料有关。 对基于裂纹扩展的金属陶瓷硬质覆层零件的设计理论进行了研究，提出了一个适应于硬质覆层零件的、用于判断界面裂纹扩展方向的新参数，即界面裂纹扩展方向的相对扩展性能参数CP。 对基于平行并位于界面的裂纹扩展的金属陶瓷硬质覆层零件设计准则进行了理论和实例研究。理论分析了该界面裂纹分别向硬质覆层内偏折、向基体内偏折、沿界面三个方向扩展的相对扩展性能参数。提出了平行并位于界面的裂纹扩展准则，根据该准则，实例分析了该界面裂纹分别沿三个方向扩展的最大能量释放率、相对扩展性能参数及扩展角与载荷作用角ψ、覆层厚度比h₁/h、载荷Q大小及零件组成更多还原

【Abstract】 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更多还原