金属/粉煤灰基球形复合定形相变材料釉质涂层制备工艺

以粉煤灰为基体材料,铝粉为相变介质,采用混合烧结法制备直径为15 mm的球形高温复合定形相变材料,利用浸釉法,采用四种烧结制度制备低温黑釉表面涂层,通过渗水率及微观表征评价其防水性能。研究表明,釉层烧结温度及釉浆浓度对釉层性能有显著影响。在釉层烧结温度为950 ℃的条件下,釉浆体积浓度高于90%时,由于坯釉之间膨胀系数差异过大,以及有机分解产物在釉粉末熔融前尚未完全释放而导致釉层龟裂和焦化;当体积浓度大于80%而小于90%时,釉层表面致密度增加,防水性能增强,但存在流釉现象。烧结温度为870 ℃及810 ℃,釉浆体积浓度为85%~95%时,釉面光泽度好且流釉减少,防水性能增强。烧结温度为750 ℃时,因温度过低使釉层间气体无法及时排出导致釉面针孔增多,防水性能下降。对比四种烧结制度下釉层性能,当釉层的最高烧结温度为810 ℃,浆料体积浓度为88%～92%时,涂层致密度高,与球形相变材料表面之间密着性好,防水性能突出,实验重复性良好。

Preparation Technology of Enamel Coating of Metal/Fly Ash-Based Spherical Composite Fixed Phase Change Materials

Using fly ash as the matrix material and aluminum powder as the phase change medium, the spherical high temperature composite fixed phase change material with diameter of 15 mm was prepared by the mixed sintering method. The surface coating of low temperature black glaze was prepared by dipping glaze method and four sintering systems, and its waterproof property was evaluated by water permeability and microscopic characterization. Researches show that the sintering temperature of glaze layer and glaze concentration have significant influence on glaze layer properties. When the sintering temperature of glaze layer is 950 ℃, the glaze volume concentration is higher than 90%, the glaze layer cracks and coking are caused by the large difference in expansion coefficient between the blank glazes and the incomplete release of organic decomposition products before the glaze power melting; the volume concentration is more than 80% and less than 90%, the surface density of glaze layer increases and the waterproof property is enhanced, but there is the flow phenomenon of glaze. When the sintering temperature is 870 ℃ and 810 ℃, and the glaze volume concentration is 85% to 95%, the glaze gloss is good, the flow glaze is reduced, and the waterproof property is enhanced. When the sintering temperature of glaze layer is 750 ℃, because the temperature is too low, the gas between glaze layers cannot be discharged in time, it leads to the increase of pinholes in glaze surface and the decline of waterproof property. Compared the properties of glaze layer under four sintering systems, when the highest sintering temperature of glaze layer is 810 ℃ and slurry volume concentration is 88% to 92%, the coating has high density, good tightness with the surface of spherical phase change material, outstanding waterproof property, and good experiment repeatability.