过冷Cu_(70)Ni_(30)熔体在石英玻璃涂层壳型中过冷遗传性

Undercooling Heredity of Cu_(70)Ni_(30) Alloy Melts in Non catalytic Crystal Coating Mould

在熔模铸造壳型内表面基体玻璃涂层（Ｂ）上，用溶胶－凝胶原理制备了非晶薄膜涂层（Ｆ），ＦＴＩＲ和ＴＧＡ－ＤＴＡ 分析结果表明，裂纹发生在室温～４００℃加热区间，产生的主要原因，是热处理过程中涂层吸附水、醇快速解附引起薄膜膨胀所致，这一过程中涂层的热失重占总失重量的８９．５％ 。为此，用分级热处理工艺制备了无裂纹Ｂ－Ｆ复合涂层，ＸＲＤ分析结果表明，该涂层为ＳｉＯ２ 玻璃态。将净化后获得深过冷的Ｃｕ７０Ｎｉ３０合金熔体浇入Ｂ－Ｆ涂层中，获得了１９８Ｋ深过冷，其过冷度遗传率达到了０．７６。

A SiO 2 glassy film coating was prepared by dip coating process on the inner surface of investment casting molds that had SiO 2 glass lined coating using sol gel principle.When the gel film was analyzed by using FTIR and TGA methods,it was found that its crack property was sensitive to heating process parameters.The analytical results also show that cracking in glass converting heating occurs in the range of ambient temperature to 400℃.The expansion of the film coating,caused by rapid evaporation of water and alcohol that absorb between the networks and form during progress polymerization of the gel,plays a key role in cracking.During this evaporation,the losing weight is amount to 89.5% of the total one.For the purpose of solving the cracking,an effective step heating treatment is adopted to prepare the sound B F composite coating with SiO 2 glass structure proved by X ray diffraction.198K undercooling was achieved that means the undercooling heredity was 0.76 when the undercooled Cu 70 Ni 30 melts was poured into the mold.