Bristle Blasting Surface Preparation in Thermal Spraying
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Bristle Blasting Surface Preparation in Thermal Spraying Yingying Ding1 • Hui Li1 • Yingliang Tian1
Submitted: 30 May 2018 / in revised form: 3 December 2018 Ó ASM International 2019
Abstract The adhesive strength to the substrate plays an important role in the performance of thermal-sprayed coatings and could determine the coating’s service life. It depends to a large extent on the state of the substrate surface prior to coating deposition. In this work, a novel surface pretreatment technique was introduced to thermal spraying, namely, bristle blasting. The adhesive strengths of a plasma-sprayed metallic coating (Ni5Al) and a ceramic coating (Al2O3) were examined and compared to that of coatings sprayed with conventional grit blasting surface pretreatment. A mild steel and an aluminum alloy were selected as substrate materials. The results indicated that bristle blasting could be a practical solution for steel and aluminum alloys when grit blasting is not applicable on site. The adhesion of the sprayed coatings with different pretreatments increased sequentially from mechanical grinding, bristle blasting to grit blasting. The adhesive strength of the Ni5Al coating deposited on the bristleblasted substrate reached 60% of the adhesive strength of a coating deposited with the traditional grit-blasting pretreatment, while for the alumina coating, it was only about 30%. Moreover, the effect of substrate materials should be considered when using bristle blasting as a surface preparation. Keywords adhesive strength APS bristle blasting sand blasting surface morphology surface preparation & Hui Li [email protected] Yingying Ding [email protected] 1
College of Materials Science and Engineering, Beijing University of Technology, Beijing, China
Introduction Thermal-sprayed coatings have been widely used in various industrial sectors for surface engineering solutions. The coating needs to have sufficient adhesive strength with the substrate, which is also the minimum service requirement. Usually, the substrate surface is carefully prepared prior to spraying (e.g., grit blasting) in order to offer a cleaned and roughened surface providing an adequate bonding for the deposited coating (Ref 1). This procedure is a necessary step, which plays a crucial role in the overall performance of the coating. In the past several decades, some novel methods of substrate surface pre-treatment have been explored, including high-pressure water jet blasting (Ref 2, 3), dry ice blasting (Ref 4, 5), pulsed laser ablation (Ref 6), laser surface texturing (Ref 7) and mechanical patterning (Ref 8). Those promising methods are meaningful when the operation of grit blasting is unavailable or undesirable. For example, soft substrate materials such as aluminum alloys, copper, etc., suffer greatly from embedded grit particles at the substrate/coating interface. In addition, in some on-site operations, it is quite difficult to use standard grit-blasting machines that usually require air compressors and consume la
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