Because the majority of component failures in service can be attributed to surface-initiated effects, there is much to be gained by the specification of an appropriate surface coating for the working environment. Unfortunately, the range of coatings available, and their interaction with the materials to which they are applied, makes this a task for which considerable expertise is required. In this paper we report progress in development of the PRECEPT knowledge-based computer system, which is being constructed to aid the engineering designer in making an informed selection of surface coatings and materials to satisfy the design and service requirements of a component. In the paper we discuss the strategy for selecting surfaces based on the criteria of resistance to wear, fatigue and corrosion as well as the physical properties required of the bulk material. Fundamental to the selection process is the concept of a combination; that is, a material and coating considered together as a single entity, with unique properties. This has considerable implications for the selection process, data and knowledge gathering and the implementation of the system. These points are discussed together with initial results of user testing the prototype system.
