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高速氧燃气 (HVOF)热喷涂已经被成功地用来在热障涂层 (TBC)应用领域沉积氧化钇稳定的氧化锆 (YSZ)涂层。使用氢气作为燃气 ,在范围有限的喷涂条件下得到了结合良好的涂层。经对喷涂参数 ,如氢氧比、喷涂距离以及基体冷却进行研究发现 ,喷涂距离对涂层质量影响明显。在所试验的各种氢氧比的条件下 ,从喷枪出口起 ,在 75 mm到 12 5 mm内得到了结合良好的涂层。与空气等离子喷涂 (APS)沉积的YSZ涂层相比 ,HVOF沉积涂层以正方晶体相形式表现出更好的稳定性 ,并且具有一致的的密度、表面粗糙度和横截面显微硬度。特别值得注意的是 ,HVOF涂层的横断面揭示出更加均质的结构。很多理论模型预测在 HVOF火焰里 ,YSZ不可能被熔化 ,因此 ,用这一工艺不可能沉积出可靠的 YSZ涂层。在本研究工作中得到的试验结果是 :在 HVOF枪作业时燃烧室的压力高达 0 .39MPa,使得绝热火焰温度值达到了氧化锆的熔点以上。在这种条件下 ,Ranz- Marshell热传输模型预测 HVOF喷涂粒子的表面温度 Tp高到足以使得小的氧化锆粒子 (10μm)被部份熔化 ,Tp=(1.10～0 .95 ) Tm。进一步的分析证明 ,对于较大的粒子 (38μm) ,当粒子温度 Tp=(0 .5 9～0 .6 0 ) Tm时 ,即产生了结合良好的涂层 ,这表示在 HVOF喷涂中 ,烧结可能对氧化锆的沉积起到一?
High velocity oxyfuel (HVOF) thermal spraying has been successfully used to deposit yttria-stabilized zirconia (YSZ) coatings in thermal barrier coating (TBC) applications. Using hydrogen as the fuel gas, a well-bonded coating is obtained under a limited range of spraying conditions. The spray parameters, such as hydrogen and oxygen ratio, spraying distance and the substrate cooling study found that spray distance on the coating quality significantly. At the various OH ratios tested, a well-bonded coating was obtained within 75 mm to 125 mm from the gun exit. The HVOF deposition coating shows better stability as a tetragonal phase compared to air plasma sprayed (APS) deposited YSZ coatings with consistent density, surface roughness and cross-section microhardness. Of particular note is that the cross section of the HVOF coating reveals a more homogeneous structure. Many theoretical models predict that YSZ can not be melted in the HVOF flame, so it is impossible to deposit a reliable YSZ coating with this process. The test results obtained in this research work are as follows: the pressure of the combustion chamber reaches as high as 0.39 MPa during the operation of the HVOF gun, so that the temperature of the adiabatic flame reaches above the melting point of zirconia. Under these conditions, the Ranz-Marshell heat transfer model predicts that the surface temperature Tp of the HVOF spray particles is high enough that small zirconia particles (10 μm) are partially melted, Tp = (1.10-0.9575) Tm. Further analysis demonstrated that for larger particles (38 μm), a well-bonded coating was produced at Tp = (0.59-0.600) Tm, which means that in HVOF spraying, sintering May Zirconia deposition play a?