Showing papers by "Joachim Heberlein published in 2021"

Thermal Spray Fundamentals : From Powder to Part

Abstract: This book is based on a series of continuing education courses which have been offered by the authors across the world in conjunction with the International Symposium on Plasma Chemistry (ISPC) as part of its summer school over the period 1995-2011. A similar course, though more oriented toward thermal spray technology, was also offered by the authors in conjunction with ASM International Thermal Spray Conferences (ITSC) over the period 1998-2010. Both courses were offered to graduate students, practicing engineers, and researchers actively involved in the field of thermal plasmas. Their emphasis was on the fundamentals behind plasma processing and thermal spray technology, and the aim was to provide a grassroot understanding of the basic phenomena involved, necessary for taking the technology over the crucial step from being an "art" based on operator talent and experience to a mature science with quantitative predictive capabilities. This step did not come easily and without the intense involvement of many leading researchers in this field across the world. The three determining factors which were of critical importance to the evolution of this field over the past three decades are as follows: * Major improvement in process diagnostics and online controls * The fast and significant development of numerical modeling and computing capabilities * Major development in materials science and materials characterization techniques In the process of preparation of the manuscript for this book, which spans many years, the authors were confronted with the critical need to strike a good balance between the need to be concise in the overall presentation of the subject and being inclusive in stressing the fundaments without overlooking the important applications which were the economical driver of the technology. New technologies were also developed over this period which, while not being "plasma technologies," were relevant to the overall field of surface treatment and coating. These were accordingly included in the book such as the combustion-based technologies and "cold spray." We have no pretensions about having covered every aspect of this technology or exhaustively reported on every relevant publication in this field. Exhaustive lists of references are given at the end of each chapter. For those who were not cited, our apologies, it was not intentional. A book of this size and scope could not have been possible without the extensive help of students, research assistants, colleagues, and associates. Our sincere thanks to all who have helped make this book a reality. Particular thanks are due to Dr. Rudolf Henne who so generously gave his time in the process of reviewing the manuscript of the book in its final preparation stage. We also appreciate his willingness to write the foreword for this book which reflects his long and broad experience in the field of thermal spray. The financial assistance of the numerous government and private funding agencies and industrial partners who have also supported the basic and applied research behind this technology in our respective research laboratories is gratefully acknowledged. Our sincere thanks to our respective families and life partners, Paulette Fauchais, Yuko Heberlein, and Alice Boulos who had to cope with the long hours of intense personal efforts that were needed to complete this book.

Introduction to Thermal Spray

Abstract: The increasing demand for combined functional material requirements such as high-temperature corrosion resistance in addition to resistance to abrasive wear, strength, and light weight has led to the ever-increasing demand for coatings. Cost concerns have added to the challenge of meeting all of these requirements in a simple functional and economical solution. In this introductory chapter, a brief review of the history of the development of thermal spray processes is given including a discussion of alternate approaches that can be used for the deposition of thin and thick coatings. Highlights of some of the major industrial applications of thermal spray coating technology are reviewed next followed by an overview of the structure of the contents of this book.

Thermal Spray Process Integration

Abstract: Process integration (PI) is the most important and critical step in setting up an efficient, smooth, flawless, reliable, cost-effective, and safe industrial-scale operation. It has to be conceived with a thorough knowledge of the technology involved, its potential and limitations, required infrastructure, potential hazard, as well as health and safety concerns. In this chapter, an overview is presented of the steps that need to be taken for the setting up of thermal spray facility.

Plasma Transferred Arc Coating

Abstract: The plasma transferred arc (PTA) coating process was developed in the 1960s for the rebuilding and repair of worn parts and the hard facing of parts exposed to extreme abrasion and corrosion. Regular steel parts with an appropriate PTA coating can exhibit superior corrosion and wear-resistant behavior even compared to specialty alloys. The process is significantly different from other coating processes, including plasma spraying, as the surface of substrate is locally molten in the process creating a strong metallurgical bond between the molten coating material and the substrate if they are metallurgical compatibles. The substrate, in most of the cases, serves as the anode for the transferred arc and only exceptionally as cathode to significantly limit the heat flux to the substrate and clean its surface. The powder to be deposited is introduced into the arc plasma through two or more orifices located on a ring surrounding the exit of the plasma torch nozzle. A further annular slot surrounding the powder injection ring provides the shield gas flow, necessary to avoid reaction of the molten metal with the environmental air. Once the molten metal cools and freezes, it creates a metal matrix composite coating, the mechanical and metallurgical properties of which can differ from those of the substrate or the coating material. Compared to other thermal spray processes, PTA has the major advantage that alloy formation can take place in the metal pool during the process, allowing for a wider range of combinations of metal compounds or metal matrix composites. This chapter is devoted to PTA used for coatings and hard facing, describing their basic design features, typical performance characteristics, and applications.

Powders, Wires, and Cords

Abstract: Powders, wires, or cords are the key components on which the quality of the coating obtained using thermal spray strongly depends. As discussed throughout this book, Thermal Spray Technology centers around the use of mechanical, chemical, or electrical energy to develop a high energy gas stream in which the material to be sprayed is injected in the form of a powder, wire, cord, suspension, or solution. On contact with the high energy spraying medium which transforms the injected material into a high energy spray of individual particles or molten droplets that are entrained by the process gas and projected against the substrate forming splats. The coating is formed through the layering of these splats with strong adhesion to the surface of the substrate and the required microstructure for its functional role whether it is for wear or corrosion protection, thermal protection, or any of other functional properties.