Chapter 4 - Evaporation: Processes, Bulk Microstructures, and Mechanical Properties

Abstract

This chapter reviews the evaporation technologies, theory and mechanisms, processes, deposition of various types of materials, the evolution of the microstructure and its relationship to the properties of the deposits, preparation of high-purity metals, current and future applications, and cost analysis. Physical vapor deposition (PVD) technology consists of the techniques of evaporation, ion plating and sputtering. It is used to deposit films and coatings or self-supported shapes such as sheet, foil, and tubing. The thickness of the deposits can vary from angstroms to millimeters. The wide variety of applications of these techniques ranges from decorative to utilitarian over significant segments of the engineering, chemical, nuclear, microelectronics and related industries. Their use has been increasing at a very rapid rate since modern technology demands multiple, and often conflicting, sets of properties from engineering materials, e.g., combinations of two or more of the following: high-temperature strength, impact strength, specific optical, electrical or magnetic properties, wear resistance, ability to be fabricated into complex shapes, biocompatibility, cost, etc. A single or monolithic material cannot meet such demands in high-technology applications. The solution is, therefore, a composite material, i.e. a core material and a coating each having the requisite properties to fulfill the specifications. PVD technology is very versatile, enabling one to deposit virtually every type of inorganic material – metals, alloys, compounds and mixtures thereof, as well as some organic materials. The thickness limits for thin and thick films are somewhat arbitrary.