In this study, ceramic-matrix composites consisting of elongated metal (CoNbZr) particles in a cordierite (MgAlSiO) matrix were produced by plasma spraying. The metal powder was injected into the plasma jet downstream of the ceramic powder to minimize metal decomposition and oxidation. The microstructure and composition of cermet coatings containing 5, 10, and 20 vol% metal were analyzed by SEM and XRD and their electromagnetic properties were evaluated via saturation magnetization, permittivity, and permeability measurements. As expected, flake-shaped metallic particles were obtained and all coatings exhibited soft ferromagnetic behavior.

This study compares the morphology, porosity, and purity of yttria powders produced by spray drying, spray drying and sintering (SDS), and spray drying and plasma fusion (SDPF). The surface morphology of each type of powder is examined by SEM. Pore volume and density are determined by Hg porosimetry, and impurity concentrations are assessed via glow discharge mass spectrometry (GDMS). Coatings made from the powders by means of air plasma spraying are evaluated based on porosity, spray time, powder consumption, and embedded fine particles.

In this work, alumina coatings are produced by air plasma spraying (APS) using dense powders ranging in size from 3 to 36 µm and one porous powder with an average particle size of 33 µm. Two spray systems were used, one rated at 40 kW, the other at 100 kW. The powders were applied to grit-blasted Al 6061 and low-carbon steel substrates. Coatings applied to Al 6061 using the high-power sprayer and 3 µm powder peeled off, likely due to thermal shock and mismatch. For all other coatings, the microstructure was examined by cross-sectional SEM, porosity was estimated via optical microscopy, and dielectric strength and volume resistivity were measured. Coatings formed from 3 µm powder were found to be dense with a mostly γ-phase crystal structure. Surprisingly, however, their volume resistivity was lower than that of more porous coatings with high amounts of α-phase. The findings show that, in the case of resistivity, spray equipment has a bigger influence than particle size, but with coating density, the opposite is true.

This paper describes how effective medium theory and fractal analysis are used to investigate nonlinear microstructure-property relationships in HVOF-sprayed composite coatings produced from nano Fe-(β-SiC/SiO 2 ) agglomerate powders in order to optimize microwave absorption performance. The powder used in the study was prepared by spray granulation and deposited on Fe substrates. The microstructure of the powder and coatings was examined by SEM, the phase structure was determined by XRD analysis, and electrical permittivity and permeability were measured. To simplify calculations, electromagnetic absorption phases in the coating were assumed to be periodically distributed cubes. The results of the study indicate that multi-fractal diffraction in the coating microstructure facilitates the absorption of microwaves and is optimized when the mass fraction of nano βSiC in the composite is 28 wt%.

Evaluating and understanding the relationship between processing, microstructure and performance of a dielectric coating is essential for its practical usage and reliable application. In this study, the role of the powder feedstock on the properties of atmospheric plasma sprayed forsterite (Mg 2 SiO 4 ) dielectric coatings was investigated by using different forsterite powder cuts. The microstructural and porosity characteristics of the coatings associated with the spray conditions employed were assessed via scanning electron microscopy (SEM) and image analysis. The phase composition of the coatings was studied via X-ray diffraction and their crystallinity index determined. The electrical insulating characteristics were investigated using the dielectric breakdown test. The obtained electrical properties were correlated with the microstructural characteristics. Ultimately, a performance comparison between forsterite and other dielectric coatings tested in similar conditions is presented.

Thermal spray coatings are used for a broad range of purposes in the semiconductor equipment industry. A primary use of thermal spray coatings for thin film applications is to provide surfaces on process chamber components that promote particle reduction and contamination control during chamber operations. Coatings are also used to provide the desired dielectric properties for critical components such as electrostatic chucks (ESC) and heater pedestals; to prove chemical and corrosion-resistance for process kit components and showerheads; as well as serving a wide range of other purposes. This paper reviews future needs for thermal spray coatings in semiconductor equipment and identifies some of today’s coating challenges. Areas discussed include coating design considerations; chemical, corrosion and plasma erosion issues influencing the selection of materials, coatings and processes. Brief discussion will be provided for future anticipated needs in materials, coatings, processing and the manufacture of thermal spray coatings for such applications.

Thermal spray metallic coatings are used for a range of applications in the semiconductor equipment industry including applications from particle reduction to precious metal reclaim in chamber operations during thin film deposition. Thermal spray coatings assist in reducing part costs, increasing product performance and lifetimes, and reducing chamber maintenance. The processing parameters in two-wire arc spraying of aluminum are traditionally used to provide a range of coating properties in industry from dense coatings for corrosion control applications- to rough texture coatings for anti-slip applications. Thus, the two-wire arc processing parameters selected for use for semiconductor applications are critical for surviving the semiconductor processing environment and increasing product performance. Important two wire processing parameters include current, voltage, atomizing air pressure, and stand-off distance between the gun and target (sprayed part). Secondary processing parameters including robotic traverse rate, air cooling, part manipulation (turntable speed, etc.) and others. Further, the specifics of the two-wire arc gun design (make/model), nozzle diameter, air caps, and wire diameter are also important variables. Current and voltage are important parameters for generating the electric arc for melting the aluminum wire. An optimum processing window exists for the range of current and voltage used for producing the aluminum coatings. The atomizing air pressure also has an optimum range for atomizing the molten aluminum produced from the electric arc. A range of atomizing air pressures are used to produce a range of coatings from dense to rougher textured coatings. Higher operating current increases the quantity of molten producing the coatings, and the lower operating current reduces the spray rates of the aluminum to be atomized. This paper examines the two-wire arc parameters producing aluminum coatings. Two-wire arc parameters to be examined include current, voltage, atomizing air pressure and stand-off distance varied to produce coatings. The coating produced from these parameter changes will be investigated in terms of microstructure and mechanical properties. The microstructural investigation will involve porosity analysis. Mechanical property testing will include tensile-adhesion bond strength. The surface roughness will also be investigated