Recent Developments in Surface Engineering of Materials

Abstract

Engineering approaches to improve surface properties such as surface finish/appearance, hardness/strength, wear resistance, corrosion resistance, environment resistance, and heat resistance have been known since prehistoric times. The manufacturing of several ancient objects can often be traced to processes like surface painting (use of natural pigments), machining (use of sandstone, bone, and metal tools), and heat treatments (use of soybean grains for carbonitriding of steel). While most of the modern surface engineering approaches have evolved from these processes, the past century has also witnessed rapid development of newer processes based on electroplating, thermal spraying, directed beam (ion, laser, and electron) processing, and cold spraying. These processes are now utilized for depositing a range of nanostructured, amorphous, or composite materials for multiple functionalities (hardness/wear resistance, strength/ toughness, corrosion resistance, heat/environment resistance, biocompatibility and cell adhesion, and hydrophobicity). Surface engineering is a very active area, introducing regular developments on various fronts, including fundamental research, technology development, and extension in newer applications. Some of these developments were captured at the symposium Advances in Surface Engineering: Alloyed and Composite Coatings II at the TMS 2013 Annual Meeting (San Antonio, TX; March 3–7, 2013). This symposium was sponsored by the Surface Engineering Committee of the TMS Materials Processing & Manufacturing Division (MPMD) and was partially funded by the U.S. Office of Naval Research (ONR). The symposium featured 59 presentations including 14 invited talks and several student presentations. This was a well-attended, hugely successful symposium, with discussions resulting in an important direction for the future activities of the committee. Most of the recent surface engineering developments discussed in the TMS 2013 symposium are highlighted in the articles published in this JOM issue. These articles represent the current state-ofthe-art and indicate emerging areas in surface engineering. In ‘‘Advances in Laser Surface Engineering: Tackling the Cracking Problem in Laser Deposited Ni-Cr-B-Si-C Alloys,’’ I. Hemmati et al. examine the idea of microstructural refinement for reducing the cracking tendency of Ni-Cr-B-Si-C alloys deposited by laser cladding. This work indicates that effective toughening of these alloys could not be reached solely by refinement of the hard precipitates and that the modification of the eutectic structure or disruption of its continuous network is needed. In ‘‘Nanomechanical Properties and Thermal Conductivity Estimation of Plasma Sprayed Solid Oxide Fuel Cell Components: Ceria Doped Yttria Stabilized Zirconia Electrolyte,’’ N. Mahato et al. demonstrated layered fabrication of solid oxide fuel cell (SOFC) components using an atmospheric plasma spraying method. The nanomechanical behavior of the deposited SOFC composite layers is evaluated. In ‘‘Characterization of Nanostructured and Ultrafine Grain Aluminum-Silicon Claddings using the Nano-Impact Indentation Technique,’’ J. Arreguin-Zavala et al. report that dynamic hardness of the material becomes independent of load using a nano-impact indentation technique. Their analysis shows that better correlation can be established between dry sliding wear and dynamic hardness. In ‘‘Abnormal Nitride Morphologies upon Nitriding Iron-Based Substrates,’’ Sai Ramudi Meka and Eric Jan Mittemeijer provide an overview of different nitride morphologies formed upon Sandip P. Harimkar, Chair of the Surface Engineering Committee of the TMS Materials Processing & Manufacturing Division (MPMD); Srinivasa Rao Bakshi, Vice Chair of the Surface Engineering Committee of TMS; and Arvind Agarwal are the JOM advisors for the Surface Engineering Committee. JOM, Vol. 65, No. 6, 2013