電磁鋼片表面分析與塗膜特性研究

Surface Morphology and Coating Property of Electrical Steel

陳逸(Yi Chen)

指導教授 ： 林招松

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201703937

摘要

電磁鋼片主要應用於提供發電機、馬達或變壓器等產品的磁迴路，進而進行能量轉換，鋼片上的絕緣塗膜則具有提供堆疊時的絕緣特性與抗蝕能力的功能，故塗膜的特性亦是左右鋼片特性的一大重點。本研究主要目的在於研究鋼片及塗膜的表面特性與塗膜附著性間的關聯，找出影響附著性的原因並加以解決，使目前使用的絕緣塗膜在性質上有更全面的表現。
本研究首先針對電磁鋼片表面反應性做分析，透過微結構觀察及電化學檢測發現，各型號鋼片表面的氧化層結構有所差異，此差異推測來自合金元素中銻元素的添加，未添加銻元素的鋼片表面為氧化鋁及氧化鐵混合層，平均厚度約為25nm，結構較為疏鬆；而添加銻元素的鋼片表面則只有氧化鋁層，平均厚度約為10nm，結構較為緻密。氧化層結構差異會影響底材與塗料的反應性，進而改變界面鍵結強度，影響後續塗膜的附著性。除了鋼片表面結構外，也針對塗膜在應力消除退火(SRA)前後的特性做分析，不同附著性的塗膜有退火前表面高低起伏及退火後裂紋大小的差異。表面高低起伏為塗膜厚度不均所造成；而裂紋的產生，主要是因為退火時樹脂裂解，塗膜體積收縮量所造成。實驗結果顯示，塗膜退火後的裂紋大小與塗膜厚度及樹脂含量有關，降低塗膜厚度及樹脂含量，可以有效抑制退火後裂紋產生。而塗膜的附著性與退火後裂紋大小有關；實驗發現，當塗膜平均裂紋寬度為350nm，在退火後有較佳的附著性；而平均裂紋寬度為450nm，塗膜退火後附著性較差。

關鍵字

電磁鋼片 ； 絕緣塗膜 ； 銻元素 ； 氧化層 ； 附著性

並列摘要

Electrical steel is a functional material, also known as silicon steel, mainly used in the core of generators, motors or transformers. The insulating coating, coated the electrical steel, has the function of providing the insulating property and the corrosion resistance. In addition to the insulating property and corrosion resistance, the adhesion property of the coating is also the element that determining the quality of the coating. China Steel Corporation is currently developing a trivalent chromium coating (C628). This coating has a good adhesion property on some specific grades of electrical steels, but some are not. According to experimental observation, different alloying elements or annealing temperature will seriously affect the adhesion property of the coating. Therefore, the main purpose of this study is to understand the relationship between the surface properties of the electrical steel and the adhesion property of the coating. Hoping to make the current use of the insulating coating more comprehensive by solving the problem that affect the adhesion property.
In this study, the surface reactivity of the electrical steels with different alloying elements is analyzed. The microstructural observation showed that the structure and the composition of the oxidation layer on the surface of each type of steels are different. For example, the surface of the 35CS250 electrical steel was a mixed layer with alumina and iron oxide, the average thickness of the layer is about 25nm; the surface of the 35CS250H electrical steel is only an alumina layer, the average thickness of the layer is about 10nm. The difference of the structure affects the reactivity of the coating process, resulting in the difference in the bonding strength of the coating-substrate interface, which affects the adhesion property of the insulating coating.
In addition to the surface structure, the property of the coating, with or without passing the stress relief annealing (SRA) process, were also studied. By microstructure observation, found that there were several major differences on the different adhesion property of coating. That is the thickness of the insulating coating and the size of the crack after annealing. The phenomenon of crack formation is mainly due to the crack of resin, resulting in the volume shrinkage of the coating during annealing. It is found that the adhesion property of the coating is related to the size of the crack after annealing. The average crack size of the coating on the 35CS250 electrical steel is about 350nm, having better adhesion property after annealing. The average crack size of the coating on the 35CS250H electrical steel is about 450nm, having poor adhesion property after annealing.

並列關鍵字

Electrical steel ； insulating coating ； antimony ； oxidation layer ； adhesion property

參考文獻

2. WU, J.-C., P.-C. SUN, and P. CHEN, The Application of Phosphate Treatment for Chromium-Free Insulating Coating on Electrical Steel.

3. Jenko, M., et al., AES studies of antimony surface segregation in non-oriented silicon steel. Journal of magnetism and magnetic materials, 1994. 133(1-3): p. 229-232.

4. Littmann, M., Iron and silicon-iron alloys. IEEE Transactions on Magnetics, 1971. 7(1): p. 48-60.

5. Shimanaka, H., et al., Recent development of non-oriented electrical steel sheets. Journal of Magnetism and Magnetic Materials, 1982. 26(1): p. 57-64.

7. Coombs, A., et al., Review of the types, properties, advantages, and latest developments in insulating coatings on nonoriented electrical steels. IEEE transactions on magnetics, 2001. 37(1): p. 544-557.