Effect on microstructure of TiO 2 rate in Al 2 O 3 TiO 2 composite coating produced using plasma spray method
S. ISLAK1,*
,
S. BUYTOZ2,
E. ERSOZ2,
N. ORHAN2,
J. STOKES3,
M. SALEEM HASHMI3,
I. SOMUNKIRAN2,
N. TOSUN2
Affiliation
- Cide Rifat Ilgaz Vocational High School, Kastamonu University, 37600 Kastamonu, Turkey
- Metallurgy and Materials Engineering, Technology Faculty, Firat University, 23119 Elazig, Turkey
- School of Mechanical and Manufacturing Engineering, DCU, Dublin, Ireland
Abstract
In this study, Al2O3-TiO2 composite coatings were thermally sprayed on the SAE 1040 steel using atmospheric plasma spray (APS) process of mixed different rates micron–sized TiO2 and micron-sized Al2O3 powders. The effects of TiO2 addition on the microstructure, phase compositions and microhardness of the coatings were investigated by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD) and microhardness tester. The results show that the Al2O3-TiO2 composite coatings consists of both fully melted regions and partially melted regions, and the fully melted region has a lamellar-like structure. Phase transformations from mainly stable α-Al2O3 and anatase-TiO2 in the powders to predominant metastable γ-Al2O3, rutile-TiO2 and Al2TiO5 phase in the Al2O3-TiO2 composite coatings were observed. It was determined that the pore content decreased with the increased in the TiO2 powder rate. The microhardness of the coating layers was 3-4.5 times higher than substrate material. The average microhardness values of the coatings were found to reach 650-860 HV..
Keywords
Plasma spray, Ceramic coating, γ-Al2O3, Rutile-TiO2.
Citation
S. ISLAK, S. BUYTOZ, E. ERSOZ, N. ORHAN, J. STOKES, M. SALEEM HASHMI, I. SOMUNKIRAN, N. TOSUN, Effect on microstructure of TiO 2 rate in Al 2 O 3 TiO 2 composite coating produced using plasma spray method, Optoelectronics and Advanced Materials - Rapid Communications, 6, 9-10, September-October 2012, pp.844-849 (2012).
Submitted at: May 15, 2012
Accepted at: Sept. 20, 2012