Ceramic foam filters play an essential role in the quest for cleanliness of cast steel parts as they facilitate turbulence reduction during mold filling as well as removal of nonmetallic inclusions. A coating on these filters is able to increase their strength and filtration efficiency by improving the adhesion of inclusions to the filter strands. In this study, Al₂O₃‐C filters were coated with an alumina slip via slip and flame spraying. The phase composition and the microstructure of the coatings were investigated before and after immersion into molten steel contained in a metal casting simulator. After contact with molten steel, Al₂O₃‐C reference filter shows intense decarburization which often influence the quality of cast steel parts due to formation of gas bubbles. Slip‐sprayed alumina coatings on such a filter promote the deposition of inclusions due to formation of a vitreous alumina layer but will also cause gas bubble formation as they exhibit a high porosity. Flame‐spray coatings have low porosity and hence, prevent formation of gas bubbles. Furthermore, they showed the highest reactivity toward the steel melt and hence, are recommended for filtration of cast products with a high demand on cleanliness.

中文翻译：

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滑涂和火焰喷涂的碳结合氧化铝过滤器与钢水的相互作用

陶瓷泡沫过滤器在追求铸钢零件清洁度方面起着至关重要的作用，因为它们有助于减少模具填充过程中的湍流并去除非金属夹杂物。这些过滤器上的涂层能够通过改善夹杂物对过滤器股线的附着力来提高其强度和过滤效率。在这项研究中，Al ₂ O ₃ -C过滤器通过滑移和火焰喷涂涂上了氧化铝滑泥。在浸入包含在金属铸造模拟器中的钢水中之前和之后，研究了涂层的相组成和微观结构。与钢水接触后，Al ₂ O ₃‐C参考滤清器显示出严重的脱碳，这通常会由于气泡的形成而影响铸钢零件的质量。由于形成了玻璃状氧化铝层，在这种过滤器上喷涂的氧化铝涂层促进了夹杂物的沉积，但由于它们显示出高孔隙率，因此也会导致气泡的形成。火焰喷涂涂层的孔隙率低，因此可以防止气泡的形成。此外，它们对钢水的反应性最高，因此建议用于对清洁度有较高要求的铸件的过滤。