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首页> 外文会议>2003 International Thermal Spray Conference Vol.2; May 5-8, 2003; Orlando, Florida, USA >Improved Oxidation Life of Segmented Plasma Sprayed 8YSZ Thermal Barrier Coatings
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Improved Oxidation Life of Segmented Plasma Sprayed 8YSZ Thermal Barrier Coatings

机译：改进的分段等离子喷涂8YSZ热障涂层的氧化寿命

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摘要

Somewhat unconventional plasma sprayed TBC systems were produced and evaluated by interrupted or cyclic furnace oxidation life testing. Approximately 250 μm thick 8YSZ coatings were directly sprayed onto grit blasted surfaces of PWA 1484, without a bond coat, in order to take advantage of the excellent oxidation resistance of this superalloy. For nominal sulfur contents of 1 ppmw, total coating separation took place at relatively short times (200 hr at 1100℃). Reductions in the sulfur content, by melt desulfurization commercially (0.3 ppmw) or by hydrogen annealing in the lab (0.01 ppmw), improved scale adhesion and extended life appreciably, by factors of 5-10. However, edge-initiated failure persisted, producing massive delamination as one sheet of coating. To subvert this mechanism, samples surfaces of melt desulfurized PWA 1484 were EDM'ed with a grid of grooves or ribs (～250 μm wide and high), resulting in a segmented TBC surface macrostructure. Now failure only occurred as independent single segments events. For grooved samples, 1100℃ segment life was extended to ～1000 hr for 5 mm wide segments, with no failure observed out to 2000 hr for segments ≤ 2.5 mm wide. Ribbed samples were even more durable, and segments ≤ 6 mm remained intact for 2000 hr. Larger segments failed by buckling at times inversely related to the segment width and decreased by oxidative effects at higher temperatures. This critical buckling size was consistent with that predicted for elastic buckling of a TBC plate subject to thermal expansion mismatch stresses. Thus, low sulfur substrates demonstrate appreciable coating lives without a bond coat, while rib segmenting extends life considerably.
机译：生产了一些非常规的等离子喷涂TBC系统，并通过中断或循环炉氧化寿命测试对其进行了评估。将约250μm厚的8YSZ涂层直接喷涂到PWA 1484的喷砂表面上，不使用粘结涂层，以利用这种超级合金的出色抗氧化性。对于标称硫含量为1 ppmw的情况，总涂层分离发生的时间相对较短（1100℃下200 hr）。通过商业化的熔体脱硫（0.3 ppmw）或实验室中的氢气退火（0.01 ppmw）来减少硫含量，可以使鳞片的附着力得到改善，使用寿命延长了5到10倍。然而，边缘引发的故障持续存在，作为一层涂层产生大量分层。为了颠覆这种机理，对熔融脱硫的PWA 1484的样品表面进行电火花加工，并刻上沟槽或肋条（宽约250μm，高），形成分段的TBC表面宏观结构。现在，故障仅作为独立的单段事件发生。对于开槽样品，对于5 mm宽的段，1100℃的段寿命延长到〜1000 hr，而对于≤2.5 mm宽的段，没有观察到2000 hr的失效。带肋的样本更加耐用，≤6 mm的片段在2000小时内保持完整。较大的链段有时会因与链段宽度成反比的屈曲而失效，而在较高温度下会因氧化作用而降低。该临界屈曲尺寸与对经受热膨胀失配应力的TBC板的弹性屈曲预测的尺寸一致。因此，低硫底材在没有粘结涂层的情况下具有可观的涂层寿命，而肋骨分段可大大延长使用寿命。

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