The influence of CeO{sub 2} on the corrosion resistance of laser remelted alloy spray coatings on steel
- Beijing Univ. of Aeronautics and Astronautics, Beijing (China). Materials Science and Engineering Dept.
The main compositions of iron-base amorphous self-fluxing alloy powders of 150 mesh, used in this work, are Fe, Cr, Ni, W, Mo, B, Si and C. The ranges of each element in at% are (65-70)Fe, (3-5)Cr, (2-4)Ni, (2-4)W, (1-2)Mo, (10-14)B, (4-7)Si and (2-3)C. The atomic ratio of metal-metalloid is about 80:20, so this alloy is abbreviated as M{sub 80}X{sub 20}. The material on which coatings were deposited is 1020 steel, austenitized for 1h at 880 C, water quenched, and tempered at 180 C for 1h. This heat treatment resulted in a low carbon martensite structure with a hardness of HRC35-45. After cleaning, shot blasting and preheating the steel to about 200 C, the authors sprayed a thin Ni-Al alloy layer of about 0.1--0.15mm in thickness onto the specimen by means of an oxygen-acetylene torch to provide better bonding of the coating with substrate. Then the M{sub 80}X{sub 20} and M{sub 80}X{sub 20}+8%CeO{sub 2} alloy coatings were sprayed to a thickness of about 0.6--0.8mm. The CeO{sub 2} was added as particles of 200 mesh, injected into the spray, and became a component of the alloy coating. A single pass remelting process for the coating was then conducted by means of a 3kW CO{sub 2} laser. Corrosion tests gave the following results: (1) The addition of rare earth (8%CeO{sub 2}) can improve the corrosion resistance of the laser-remelted M{sub 80}X{sub 20} alloy layer remarkably, resulting in an obvious decrease of the values of ip and i{prime}p, and hence significant improvement of passivation. (2) The addition of rare earth (8%CeO{sub 2}) lowers the corrosion rate (the corrosion rate is reduced to approximately one-third of that without rare earth) of the laser remelted M{sub 80}X{sub 20} alloy coating and also changes the corrosion morphology.
- OSTI ID:
- 27988
- Journal Information:
- Scripta Metallurgica et Materialia, Vol. 32, Issue 6; Other Information: PBD: 15 Mar 1995
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CARBON STEELS
COATINGS
IRON BASE ALLOYS
SPRAY COATING
CORROSION RESISTANCE
CHROMIUM ALLOYS
NICKEL ALLOYS
TUNGSTEN ALLOYS
MOLYBDENUM ALLOYS
BORON ALLOYS
SILICON ALLOYS
CERIUM OXIDES
METALLURGICAL EFFECTS
CARBON
MORPHOLOGY
SCANNING ELECTRON MICROSCOPY
LASER-RADIATION HEATING
ALUMINIUM ALLOYS