Role of Alloying Elements on Powder Metallurgy Steels and Spectroscopic Applications on Them

The powder metallurgy (PM) technique is suitable for mass production and is a well-established process for the low production costs of net-shaped products close to long series. The properties of the iron-based PM parts, such as strength, hardness, magnetic properties, impact, wear, and corrosion resistance, can be improved with adding various alloying elements. The desired surface performance can be achieved with various surface coating technologies. Recently, various coating techniques have been developed as discussed in the chapter. The alloying elements have a significant effect on the coating quality of the final product. Surface coating can be analyzed by examining the surface-coated powder metallurgy (PM) using infrared and Raman spectroscopy technique. This contribution focuses on the role of alloying elements on properties and coating technologies of powder metallurgy steels and Fourier transform infrared (FT-IR) and Raman spectroscopic applications on them.

A Review of the Cold Gas Dynamic Spraying Process

In this modern era, use of coatings on engineering materials has become highly inevitable. One such emerging coating method is the cold gas dynamic spraying. It is a solid-state process where deposition on to the surface of the material is done at high pressure and velocity. Adhesion of the powder to the substrate is possible because of the high amount of plastic deformation. This chapter introduces the CGDS system and discusses the types of set-ups and its modifications that are generally used. Further, the chapter delves into the process parameters in the spraying process and the correlation of these parameters with the coating properties. It also provides a comprehensive review of the current theories of bonding mechanism in cold spray. It aims to provide an overview of the material systems that have been investigated so far for cold spraying with an outline of the experimental and numerical simulation that have been researched.

Principles and Applications of Thermal Spray Coatings

The goal of the chapter is to address the fundamental theory of thermal spraying and its modern industrial applications, in particular, those involving flame spray, HVOF, plasma spray, and cold spray processes. During the last 30 years, thousands of manuscripts and various book chapters have been published in the field of thermal spray, displaying the evolution of thermally sprayed coatings in many industrial applications. Thermal spray coatings are currently interesting for different modern applications including prosthesis, thermal barriers, electrochemical catalysis, electrochemical energy conversion devices, biofouling, and self-repairing surfaces. The chapter will explain the fundamental principles of the aforementioned thermal spraying processes and discuss the effect of different controlling parameters on the final properties of the produced coatings. This chapter will also explore current and future industrial applications of thermal spray coatings.

Surface Engineering for Coating

Surface engineering includes augmentation of intrinsic properties of the boundary of the component, which isolates the continuum from surroundings known as the surface. Two main purposes of surface engineering encapsulate primarily the hardness of the surface for enhanced wear resistance and also to poise up with inter-surface frictional behavior. Today, there are many different surface engineering techniques available: starting from vacuum to atmospheric pressure, wet to dry, simple to sophisticated, and low-cost to high-cost to obtain the required purposeful distinctiveness of material. Most methods used today are dry and thus environmentally sound. This chapter describes various types of coatings over materials to get an overall idea of the technique keeping prime focus on graduate and undergraduate students.

Electroless Coating on Non-Conductive Materials

This chapter attempts to make a review of electroless metal deposition over various non-conducting substrates like for its application in the field of medical research, electrical and electronics units, household aesthetics, automobile and textile industries. Electroless coating of metals over conducting substrates have been developed, critically reviewed, and proven its worth by showing excellent desired properties over the years. This review aims to discuss the techniques that have been applied by the researchers to overcome the difficulties of coating on these materials, their influence in their physical and mechanical properties, and their prospects of use in the industries. With the discussion of the underlying coating fundamentals and its historical backgrounds, the emphasis was put into the coating deposition with sensitizations and activations of various substrates, electroless baths, and the characteristically changed properties of the materials observed in the analysis.

Fabrication of Functionally Graded Metal and Ceramic Powders Synthesized by Electroless Deposition

One of the most important factors in powder metallurgy is the powder properties that directly affect the final product properties. By using the functionally graded materials (FGMs) in powder metallurgy, the desired properties can be obtained by means of layers having microstructure having more than one feature in a single material structure. Similarly, by the production of functionally graded powders (FGPs), different properties can be obtained in a single powder structure and the materials that have different properties in the same structure are developed by integrating these powders with powder metallurgy. In this context, the FGMs synthesized from the FGPs produced by electroless deposition (ED) of metal or ceramic-based powder materials facilitates the production of advanced material. Therefore, the purpose of this chapter is on the fabrication of metal and ceramic-based FGPs by ED and to discuss of their advantages on the powder metallurgy parts.

Advances in Low Thermal Conductivity Materials for Thermal Barrier Coatings

One of the areas of research that continue to attract researchers worldwide is the development of thermal barrier coatings (TBCs) especially associated with the design of new ceramic topcoats with low thermal conductivity and a high coefficient of thermal expansion. The purpose of this chapter is to present the advances that have been achieved regarding ceramic topcoats in the last decades, making a historical journey that culminates with the contributions of this decade. The introduction of new crystalline structures and chemical compositions have opened the door to the real possibilities of replacing yttria-stabilized zirconia (YSZ) to ensure the optimal thermomechanical-chemical properties required by TBCs. Future research directions associated with this topic are also provided.

Cyclic Oxidation of Combined LTA/YSZ and Alumina Thermal Spray Coatings

Thermal barrier coatings protect the substrate from thermal diffusion, oxidation, phase transformations, elastic deformation, plastic deformation, creep deformation, thermal expansion, thermal radiation. It allows parts and components of gas turbines to withstand high temperature upto1650 °C. Cylic oxidation behavior of alumina incorporated, lanthanum titanium aluminum oxide (LaTi2Al9O19), and yttria stabilized zirconia (YSZ), that is LTA/YSZ top ceramic layer coating, was investigated. Two coating combinations, L 100 having top LTA layer thickness of 100 µm and L 150 having top layer of LTA having thickness 150 µm, were tested for thermal cycles at the temperature of 1100°C. The performances of these coatings were compared with conventional YSZ coatings. Microstructure studies, EDX, and XRD analysis demonstrated the formation of mainly LTA, LaAlO3, Al2TiO5, Al2O3, and TiO2 at 1100°C in both coatings. But in L 150 coating, the rate of oxidation was found slower than L 100 coating. Annealed L 150A and L 100A specimens show cyclic oxidation life of 272th and 250th cycles, respectively.

Surface Engineering of Materials Through Weld-Based Technologies

In this chapter, an overview of welding as a technology for surface engineering is explored. According to literature, all types of welding techniques are appropriate for coating applications. However, as a result of process characteristics, some welding processes stand out. The most used welding techniques in the metal coating are arc welding (MIG, TIG, and PAW) and oxyacetylene welding. In the coating of metals using welding techniques, the coatings produced usually have a thickness that ranges between 1 and 6 millimeters. Applications of surface coating have been studied extensively. Such applications include aeronautic industry, sports, transport industries, petroleum and chemical industries, mining, food, and in the electronic industry. Plasma MIG welding is an advanced plasma process that combines the advantages of both MIG and plasma welding. Applications of plasma MIG welding in the surface coating of metals are expected to be explored extensively in the future.

Tribological and Micro-Structural Characterization of Ni-Cu-P-W Coatings

Ni-Cu-P-W coating was deposited by electroless method on mild steel substrate to study the crystallization and tribological behavior at different annealing temperatures. Energy dispersive x-ray (EDX) analysis, scanning electron microscopy (SEM), x-ray diffraction (XRD), and differential scanning calorimeter (DSC) were used to study the composition, surface morphology, phase behavior, and thermal behavior of the coating, respectively. Tribological study was conducted using Pin-on-Disc tribotester. EDX analysis confirms the presence of Ni, Cu, P, and W in the deposit. SEM image shows the surface is dense, smooth, and without any observable nodule. Some of the samples were heat treated to 300°C, 500°C, and 700°C for 1 hour to observe the crystallographic change by XRD. One sharp crystalline peak of Ni (111) is present in all condition, but the intensity increases rapidly with the heat treatment temperature. The phase transition temperature of this quaternary coating analyzed by DSC was 431.8°C.