腐食疲労によるWC系溶射材の皮膜破壊挙動
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概要
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Fatigue tests of WC/Co(Material A)and WC/Hastelloy(Material H)thermally sprayed coatings fabricated by HVOFwere carried out in Na<SUB>2</SUB>SO<SUB>4</SUB> solution(pH6.5)in order to investigate methods of improving corrosion fatigue strength.Corrosion fatigue behaviors of thermally sprayed coatings loaded with a small cyclic stress were carefully investigated inorder to discuss the effectiveness of thermally sprayed coatings near the threshold stress σ<SUB>u</SUB> . When a fatigue test was carriedout in a solution, σu of Material A was same as that of the substrate, and σ<SUB>u</SUB> of Material H was 45% larger than the substrate.The cross sections of the coatings were observed by SEM after the fatigue test, with σ<SUB>max</SUB> = σ<SUB>u</SUB> and a stress ratio of <I>R<I> = 0.8fatigue. The crack in the substrate/coating interface, and the inter-formational delamination in the coating were observed inboth of the material coatings after the fatigue test at <I>N<I> = 1×10<SUP>6</SUP>. An interface delamination was generated, and no cracks orcorrosion pits were generated from the interface to the substrate. This was observed on both materials over <I>N<I> = 2.0×10<SUP>7</SUP>.The coating delaminations were also generated in the cases of loading cyclic stresses under σ<SUB>u</SUB> , but the delamination stayed at the substrate/coating interface, and no crack propagation was discovered after reassessment.
- 一般社団法人 日本溶射学会の論文