Zhong Xu

Plasma Surface Metallurgy of Other Materials

With many unique advantages, the double glow plasma surface metallurgy technology, or Xu-Tec, has been continuously developing into many applications with the deeper and wider coverage. This chapter introduces the research achievements in the surface alloying by the Xu-Tec process on other materials, such as copper and its alloys, niobium, molybdenum, tungsten, and C/C.

Plasma Surface Metallurgy of Titanium and Titanium Alloys

Titanium, known as the “aerospace material” or “marine material,” is an indispensable material in the modern industry. Due to its low hardness and poor thermal conductivity, the surface of titanium is prone to adhesion under a friction condition. In some special media, the passivation film on the titanium surface loses its protective ability and shows the strong chemical activity. As a consequence, proper surface modification for its physical, chemical, or mechanical property change is required for some specific applications. This chapter is to introduce Plasma Surface Metallurgy on Titanium matrix and Titanium Alloys by the double glow plasma surface alloying technology to enhance wear-, corrosion- and flame resistance.

Plasma Surface Metallurgy of Intermetallic Compounds

TiAl and Ti2AlNb as typical intermetallic compounds have better specific strength and high temperature strength than the nickel based alloys. They are the ideal high temperature structural materials in the aerospace industry. But the practical applications of intermetallic compounds are limited due to their poor wear and high temperature oxidation resistance. In this chapter, it is presented that the double glow discharge plasma surface alloying treatment with Nb, Mo, Cr and Ni–Cr–Mo–Nb has been applied to TiAl and Ti2AlNb alloys for improving their properties. The results show that after surface alloying treatments, the wear resistance of the two materials increases, and the high temperature oxidation resistance of TiAl alloy is also greatly improved as well.

Industrial Applications and Equipment Scaling-Ups of Xu-Tec Process

This chapter presents some industrial applications and associated equipments of the Xu-Tec process. Some application examples in industrial products, such as high-speed steel (HSS) saw blade, HSS colloid mill, and Ni–Cr alloy corrosion resistance steel plate, are introduced. Many possible applications in carbon steel, titanium and its alloy, intermetallic compound and other metallic materials are also discussed briefly in this chapter. The technical specifications and design principles of the industrial processing equipment scaling-up are presented.

Plasma Surface Metallurgy High-Speed Steel

This chapter introduces the plasma surface metallurgy high-speed steels (HSS) formed on the ordinary carbon steel surface by double glow plasma surface alloying technology (Xu-Tec process). The cases include W–Mo HSS, W–Mo–C HSS, W–Mo–Ti HSS, and Mo–Cr low alloy HSS, as well as plasma surface metallurgy aging hardening HSS. The process parameters, microstructures, composition distribution, and properties of above high-speed steels are presented in detail. Plasma surface metallurgy high-speed steels on the ordinary steel not only possess excellent performances by comparing to the bulk HSS materials, but also save the precious alloy elements (tungsten and molybdenum) in producing a surface layer and greatly reduce the overall material cost.

Double Glow Plasma Surface Alloying/Metallurgy Technology

This chapter introduces the double glow plasma surface metallurgy technology, ranging from its basic principle for surface alloy formation and mechanism of alloy element inter-diffusion, to the operation processing and results. The hardware configuration for the working-piece, the source electrode, gap protection and cathode power transmission device are described. The influence of the main process parameters on the surface alloying layer and the discharge modes, arc discharge and its causes are discussed in detail. In addition, some collective processing experience and the operational requirements are also introduced and discussed. The advantages of the Xu-Tec process for surface alloying treatment and its development history in China and in the USA are briefly presented.

Physical Basis of Plasma Surface Metallurgy

The plasma surface metallurgy is a new discipline field in materials science and engineering. The newly developed surface metallurgy technology, Double Glow Plasma Surface Metallurgy Technology, or the Xu-Tec process, applies a series of physical processes, such as vacuum, gas discharge, low-temperature plasma, ion sputtering, surface adsorption, and atomic diffusion, to realize a surface alloying layer into the surface of the substrate matrix. This chapter introduces some basic knowledge and physics about the double glow discharge and the processing characteristics as well. Some preliminary discussion is presented on the related physical fundamental issues that involved in the Xu-Tec process.

Double Glow Discharge Phenomenon and Its Applications

The double glow discharge phenomenon has led in the invention of “Double Glow Plasma Surface Alloying Technology”. This technology has overcome the limitation of the plasma nitriding technology which can only use nonmetallic gas elements for surface alloying. This chapter mainly introduces the double glow discharge phenomenon with its discovery, functionalities, discharge modes, and applications. The double glow hollow cathode discharge and its discharge characteristics are also introduced and discussed. The initial set of experimental setup and the result of the double glow plasma surface alloying technology have been described.

Plasma Surface Metallurgy of Iron and Steel

Iron and steel materials are the most widely used engineering materials with the largest amount of metal materials in modern production and application. To enhance the surface physical and mechanical performance of iron and steel materials, surface engineering modification is applied to coordinate the different performance requirements between the substrate and surface of iron and steel materials. This chapter introduces both the single-element and multiple-element plasma surface metallurgy processes, to form various surface alloys on iron and steel material. In addition, the plasma surface metallurgy superalloys, precipitation hardening stainless steel, and plasma surface metallurgy antibacterial stainless steel formed on the surface of steels is also introduced. The plasma surface alloying parameters, microstructures, composition distribution, and properties of above all surface alloys are presented.

Other Technologies by Double Glow Discharge Plasma Phenomenon

Inspired by double glow plasma surface metallurgy technology, a series of other innovative technologies were developed based on the double glow discharge phenomenon, such as the double glow-added arc plasma surface alloying technology and double glow plasma brazing. All the inventions have further enriched the class of double glow plasma surface alloying/metallurgy technology; expanded the scope of its research and applications. The basic principle, main functionality and characteristics of each technology are briefly introduced in this chapter.