This article discusses various control processes carried out in powder feeding, thermal spraying, and gas flow of the thermal spray process to standardize the coating quality. Quality of the entire powder feeding process can be achieved by controlling the processing of feeding equipment as well as the characteristics of the powder being fed. Gas flow control can be achieved by using rotameters, critical orifices, and thermal mass flowmeters, whose ability to provide useful information is defined by their resolution, accuracy, linearity, and repeatability. The commercial thermal spray controls discussed here include the open-loop input-based, open-loop output-based, closed-loop input-based, and closed-loop output-based or adaptive controls. The article discusses the common causes and practical solutions for arc starting problems. It also outlines certain important developments in measuring individual and collective particle velocities, temperature, and trajectories as well as other plume characteristics for the plasma spray process.

This article discusses the safety issues associated with the design and operation of thermal spray booths and spray box structures and the equipment or systems required for operating thermal spray processes. It describes the design elements necessary to mitigate sound, dust and fume, ultraviolet light, and mechanical hazards. The means selected for safeguarding personnel must be based on a formal risk assessment that meets ANSI/RIA standards. The safeguards include sensing devices, barriers, awareness signals, procedures, and training. It also provides guidelines that are intended to increase the safety awareness and the use of safety practices for gas and liquid piping and electrical equipment within thermal spray installations.

A major effort in the development of thermal spray applications has been the improvement of process reliability and predictability in response to process changes. The ability to model a process is a prerequisite to understanding and controlling it. This article provides an overview of thermal spray process modeling, as it applies to the engineering of new thermal spray equipment and coating development.

Atomic absorption spectrometry (AAS) is generally used for measuring relatively low concentrations of approximately 70 metallic or semimetallic elements in solution samples. This article describes several features that are common to three techniques, namely, AAS, atomic emission spectrometry (AES), and atomic fluorescence spectrometry (AFS). It discusses the reasons for the extreme differences in AAS sensitivities that affect AFS and AES. The article provides information on the advantages and disadvantages of the Smith/Hieftje system and two types of background correction systems, namely, the continuum-source background correction and Zeeman background correction. It also provides a list of applications of conventional AAS equipment, which includes most of the types of samples brought to laboratories for elemental analyses.