| YANG Kai-zhou,ZHAO Sui-dan.Novel Coating of High-temperature Oxidation Resistance of Engine Exhaust Valve[J],46(4):89-94 |
| Novel Coating of High-temperature Oxidation Resistance of Engine Exhaust Valve |
| Received:September 20, 2016 Revised:April 20, 2017 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2017.04.016 |
| KeyWord:engine exhaust valve high-temperature oxidation resistance laminated composite coating spray pyrolysis cyclic oxidation scratch test |
| Author | Institution |
| YANG Kai-zhou |
Chongqing Hangli Industrial Co., Ltd, Chongqing , China |
| ZHAO Sui-dan |
Chongqing Hangli Industrial Co., Ltd, Chongqing , China |
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| Abstract: |
| The work aims to improve high-temperature oxidation resistance and anti-cracking spalling resistance of exhaust valve material like 21-4N alloy, enhance service performance and extend service life of engine exhaust valve. (Al2O3-Y2O3)/ YSZ laminated ceramic composite coatings were fabricated on the surface of 21-4N alloy by means of two-step cyclic spray pyrolysis technique. The morphology and composition were studied by virtue of SEM and EDS. The cyclic oxidation resistance tests were conducted to evaluate high-temperature oxidation resistance and anti-cracking spalling resistance of the coatings, while bonding strength was studied by performing scratching test. The laminated composite coating exhibited uniform thickness and compact microstructure. In the cyclic oxidation test conducted at 900 ℃ for 100 h, the sample with coating exhibited superior high-temperature oxidation resistance, by which the weight gain and spalled mass were separately 0.3025 and 0.06 mg/cm2, far lower than that of 21-4N alloy without coating. The film-substrate bonding force (40 N) was apparently higher than that of 21-4N alloy, meeting the requirements of exhaust valve in actual working conditions. The (Al2O3-Y2O3)/YSZ laminated ceramic composite coatings fabricated on the surface of 21-4N alloy by means of two-step cyclic spray pyrolysis technique can improve high-temperature oxidation corrosion resistance of engine exhaust valve material significantly and contribute to excellent adhesion. |
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