STUDIES ON ANISOTROPIC STRUCTURE AND PROPERTIES OF CO ATINGS

Research Project

Project/Area Number	07650856
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Material processing/treatments
Research Institution	FUKUI MTECHNOLOGICAL UNIVERSITY
Principal Investigator	MARUO Hiroshi Department of Mechanical Engineering FUKUI MTECHNOLOGICAL UNIVERSITY, 工学部, 教授 (50028982)
Project Period (FY)	1995 – 1996
Project Status	Completed (Fiscal Year 1996)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1996: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1995: ¥1,500,000 (Direct Cost: ¥1,500,000)
Keywords	Plasma sprayd coating / Deformation and solidification / Splat disc / Anisotropic structure / Sound velocity in coatings / 硬さ / 溶射皮膜 / 音響伝播特性 / 溶射皮膜の変形 / プラズマ溶射皮膜 / 溶滴の変形と凝固 / ノマルスキー微分干渉顕微鏡 / 変形歪のその場観察
Research Abstract	Purpose this research project is to make clear the influence of splat accumlation on the anisotropic structure and properties of plasma sprayd coating, at the stage of spraying processing. Experimental researches were caried out for two years, 1995-1996, results obtained are summarized as follows ; 1) Observations of splat deformation on the surface of substrate. A group of spraying particles flying at almost same velocity were extracted from the massive spraying particle stream so as to confirm the deformation and solidification of droplet having similar velocity. State of deformation of splat on stainless steel plate substrate was observed with SEM microscope. 2) 2 Estimation of time to deform, and time to solidify of droplet on the substrate surface Molten droplet deforms to flat disc within a microsecond scale of time, and solidified after a time of millisecond order. These results were discussed theoretically. 3) Anisotropic structure and hardness of plasma sprayd coatings. Cross sectional microscopic structure of coatins were invesigated carefully. Lamellar structure was confirmed by the vickers hardness tests. 4) Anisotropic characteristics in sound propagation Sound velocity in perpendicular direction with respect to the zirconia coating layr, and sound velocity velocity in parallel direction were investigated with the values of 3480 m/s and 3870 m/s obtained. 5) Observation of dynamic deformation of plasma aorayd coating, with the aid of microscope. Sprayd zirconia bending specimen, polished prior to bend, was tested under three point bending loading device. Failure of coating were hardely observed in the ellastic range of substrate materials, but brittle fracture come arise suddenly due to lack of ductility of ceramic materials.