**1. Introduction**

Ceramic materials are promising candidates for wear-resistance components owing to their excellent properties such as high strength and resistance to corrosion and oxidation stability at high temperature. Nevertheless, both the high coefficient of friction of this kind of material under dry sliding and the brittleness of ceramic-matrix itself limit its practical application in

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tribological areas. Generally, incorporating solid lubricants (SLs) in ceramic matrixes solves the friction problems, which can reach a positive effect. Moreover, compound lubricants can exhibit excellent self-lubricating abilities in a wide range of temperatures because the lubri‐ cants can promote the formation of well-covered lubricating films on the surfaces of ceramics that can work effectively under different temperature [1-3]. Unfortunately, subsequent studies have shown that these composites are homogenous in terms of mechanical and tribological properties. Thus, the strength of ceramics and the lubrication of SLs cannot be fully utilized. Because the continuity of ceramic phases is destroyed by the layered structural SL phase, the mechanical property of this type of material is reduced [4,5]. In these situations, it is necessary to develop a high-strength and high-toughness self-lubricating ceramic composites.

Lamination is one of the new strategies being used to enhance the mechanical properties of ceramics. The ideas of laminated composites inspired from natural biomaterials, such as shells and teeth, are made of layered architectures combining materials with different properties. During the past decade, there are large amounts of layered ceramic composites that have been fabricated and studied [6-8]. These kinds of materials have non-catastrophic fracture behavior and damage tolerance, which exhibit much higher fracture toughness and work of fracture in them than in monolithic ceramics. Moreover, the unique configurations of the layered material allow design flexibility. Therefore, the combination of the laminated design of ceramic materials and self-lubricating ceramic composites with excellent lubricating property is a promising way to achieve the integration of mechanical and tribological properties [9-12].

For laminated self-lubricating ceramic composites, interfacial residual stress between the adjacent layers may have an important effect on their mechanical properties. Any modification or change of the interfacial structure and composition will be a determining factor in the strength of the interfacial bond and will eventually affect the toughness, strength, and fracture behavior of laminated composites [13]. Therefore, a reasonable residual stress between the adjacent layers is essential to improve the mechanical properties. Previous studies have shown that the graded design of the materials is an effective method to eliminate the interface stress of dissimilar material system [14-16]. This design concept of functionally graded materials (FGMs) was first raised by Japanese scientists in 1987 as reported in reference [14]. That is, components with different properties or structures disperse by a gradient change along with one direction instead of a homogeneous manner. Thus, the composite can exhibit different properties that are mutually exclusive at the same time, and the gradient change can eliminate the interface between components. This new-style and non-uniform composite realized the integration of structure and function, making it to have a wider prospect of application in extreme conditions.

Based on the above background, the authors prepared high-performance structural/lubricat‐ ing-functional integration ceramic composites using the design of graded laminated structure [4,17,18]. This design is conductive to the combination of mechanical and tribological properties while retaining all the advantages of these materials. The aim of this chapter is to illustrate the design, fabrication, and properties of alumina and zirconia self-lubricating composites with laminated-graded structure and to provide guidance forthe optimum design of these materials.
