CORRELATION BETWEEN DEFECT MORPHOLOGIES IN COATED FILM AND ENVIRONMENTAL DEGRADATION RESISTANCE OF PLASMA-SPRAYED CERAMIC COATINGS

等离子喷涂陶瓷涂层涂膜缺陷形貌与耐环境降解性的相关性

• 批准号: 07455057
• 负责人: KIMURA Yuji
• 金额: $ 3.58万
• 依托单位: KOUGAKUIN UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07455057/
• 关键词: Plasma-Sprayd Ceramic Coating; Corrosion; Oxidation; Defects; Penetrating defect ratio; Microstructural Grading; Sealing Treatment; Low Pressure Plasma-Spray

To utilize superior characteristics of ceramics such as high strength and chemically stable properties, accelerative developments of technologies concerning binding or combining ceramic materials with other various materials are requested. For this meaning, ceramic coating technologies are just now becoming extremely importantTo make clear the performance of plasma-sprayd ceramic coating, evaluations of various degradation characteristics of plasma-splayd ceramic coatings were conducted under corrosion and cyclic heating conditions. Then, to improve resisting characteristics of plasma-sprayd ceramic coating in these environments, sealing treatment, micro-structural grading and control of spraying atmosphere were conducted employing NiCrAlY and ZrO_2 system. Then, several investigations concerning environmental degradation characteristics of these plasma-sprayd coating system, were conducted from various view points. As a result, plasma sprayd zirconia ceramic coating do not have superi … More or resistance especially in 3%NaCl aqueous solution. And, corrosion was especially recognized in the boundary layr between ceramic top coat and undercoated NiCrAlY layrs. Therefore, the corrosion current was generated by electrochemical reactions that was occurred on the surface and in the inner part of NiCrAlY layr under the aqueous environment which was brought about by the penetration of water into interface through defects of ceramic top coat layr. And, it was recognized that micro-structural graded coating shows little improvements in corrosion properties. On the contrary, sealing treatment shows much improvement in corrosion and oxidation characteristics. Then, some evaluations of defect ratio in plasma-spray coating were conducted.Recently, it has been indicated that Low Pressure Plasma Spray (LPPS) coating has higher adhesive strength and minute microstructure. For this reason, LPPS coating has been expected to have better high temperature oxidation resistance compared with Atmospheric Plasma Spray (APS) coating Therefore, in this study, cyclic and continuous heating tests of APS coating and LPPS coating were conducted. The degradation characteristics of these two types of coatings under cyclic heating conditions were investigated. As a result, a few cracks were generated in the top coated ZrO_2-8wt%Y_2O_3 layr of the APS coating after several cycles of heating to 1000ﾟC.Therefore, oxidation of the APS coating has been suppressed. On the contrary, in the case of LPPS coatings many microcracks were generated after several cycles of heating to 1000ﾟC.Oxidation of LPPS coatings preferentially occurred due to oxygen coming into coated layrs through these cracks. The governing factor of microcrack generation in the cyclic heating process was understood from the view point of larger thermal stress generation in the rop coated ZrO_2 -8wt%Y_2O_3 layr in the case of LPPS coating due to having larger Vickers hardness. Therefore, the thermal cycle life was closely correlated to the mechanical properties change due to porosity change. Less

为了利用陶瓷的优异特性，例如高强度和化学稳定性，需要加速陶瓷材料与其他各种材料的粘合或组合技术，为此，陶瓷涂层技术变得极其重要，以明确陶瓷的性能。针对等离子喷涂陶瓷涂层在腐蚀和循环加热条件下的各种降解特性进行了评价，以提高等离子喷涂陶瓷涂层在这些环境下的耐性能、封孔处理、微观结构。采用NiCrAlY和ZrO_2体系进行了喷涂气氛的分级和控制，然后从不同角度对这些等离子喷涂涂层体系的环境降解特性进行了研究，结果表明等离子喷涂氧化锆陶瓷涂层不具有优越性。 … 尤其是在 3% NaCl 水溶液中，腐蚀在陶瓷面涂层和底涂层 NiCrAlY 层之间的边界层中尤为明显，因此，腐蚀电流是由以下原因产生的。在水环境下，水通过陶瓷面涂层缺陷渗入界面，在NiCrAlY层的表面和内部发生电化学反应，并认识到微结构梯度涂层。相反，封孔处理在腐蚀和氧化特性方面显示出很大的改善。然后，对等离子喷涂涂层的缺陷率进行了一些评估。最近，有研究表明，低压等离子喷涂。喷涂（LPPS）涂层具有更高的附着强度和微小的微观结构，因此，与大气等离子喷涂（APS）涂层相比，LPPS涂层有望具有更好的高温抗氧化性，因此，在本研究中，对LPPS涂层进行了循环和连续加热测试。对APS涂层和LPPS涂层在循环加热条件下的降解特性进行了研究，结果发现顶层涂层产生了一些裂纹。经过多次加热至1000℃后，APS涂层的ZrO_2-8wt%Y_2O_3层得到抑制。因此，APS涂层的氧化得到了抑制，相反，LPPS涂层在多次加热后产生了许多微裂纹。至 1000°C。由于氧气通过这些进入涂层，因此优先发生 LPPS 涂层的氧化LPPS涂层由于具有较大的维氏硬度，因此，从涂层ZrO_2 -8wt%Y_2O_3层产生较大热应力的角度来理解循环加热过程中微裂纹产生的主导因素。热循环寿命与孔隙率变化引起的机械性能变化密切相关。

项目成果

Hisamichi YAJIMA and Yuji KIMURA: "Degradation Characteristics of Plasma-Spray Ceramic Coatings under Cyclic Heating Conditions" Proc.of Thermal Spraying (ITSC '95) -Current Status and Future Trends-. 621-626 (1995)

Hisamichi YAJIMA 和 Yuji KIMURA：“循环加热条件下等离子喷涂陶瓷涂层的降解特性”Proc.of 热喷涂 (ITSC 95) - 当前状态和未来趋势 -。

木村雄二,吉岡寿扇: "プラズマ溶射コーティングの耐食性に及ぼす封孔処理ならびに組成傾斜化の効果" 材料と環境. Vol.46. 151-157 (1997)

Yuji Kimura、Hisao Yoshioka：“密封处理和成分梯度对等离子喷涂涂层耐腐蚀性的影响”材料与环境，第 46 卷，151-157 (1997)。

Seiji NITTA and Yuji KIMURA: "Evaluation of Defects in Ceramic Coating Films by Various Electrochemical Techniques" Trans.of the Japan Soc.of Mechanical Engineers. 61-589A. 1914-1920 (1995)

Seiji NITTA 和 Yuji KIMURA：“通过各种电化学技术评估陶瓷涂层膜的缺陷”Trans.of the Japan Soc.of Mechanical Engineers。

H.YAJIMA and Y.KIMURA: "Degradation Characteristics of Plasma-Spray Ceramic Coatings under Cycllc Heating Conditions" Proc.of Thermal Spraying(ITSC '95)-Current Status and Future Trends-. 621-626 (1995)

H.YAJIMA 和 Y.KIMURA：“循环加热条件下等离子喷涂陶瓷涂层的降解特性”Proc.of Thermal Spraying(ITSC 95)-现状和未来趋势-。

木村雄二,吉岡寿扇: "プラズマ溶射コーティングの耐食性に及ぼす封孔処理ならびに組成傾斜化の効果" 材料と環境. Vol.46,No.3. 151-157 (1997)

Yuji Kimura、Hisao Yoshioka：“密封处理和成分梯度对等离子喷涂涂层耐腐蚀性的影响”材料与环境，第 46 卷，第 3 期。151-157 (1997)。