| Technological performances and application characteristics of phosphate self-setting & formed by pouring materials were investigated, which based on quartz or fused-silica and regarded water-solubility phosphate as binder, regarded oxidize magnesium as solidify pharmaceutical. Performance and production technics of silica-base ceramic core which formed by hot-pressing were investigated. Phosphate self-setting core has been compared with it about their particular performances and technological characteristics.Performance of four series phosphate self-setting materials, JX-3, JXR, JXR-2 and JXR-3, have been tested and investigated. Having been baked under different temperature and strengthened by dipping silica sol, strength of the cores was regarded as the main objective parameter. Amount of deformation under high temperature, sintering shrinkage and density were regarded as referential index. Various factors which impacted performance of the core in making process were analysed and compared.The result shows that, strength of the core will be falling after baking in 600℃, because the wax and water has been wiped off completely in core. The average value is about 1MPa. Strength of the core can be strengthened a lot by dipping silica sol, especially in the first time. After simulating baking with shell molds in 900℃, strength of the core change little. After simulating baking under casting temperature in 1550℃, residual strength of the core will increase a little. The average value is about 6～8MPa. Under high temperature in 1500℃, amount of deformation of the core is a little. Because of the different heat expansion coefficient of aggregate, JXR which all based on fused-silica is the min, JX-3 which all based on quartz is the max. The average value of shrinking percentage after baking is about 1%. Density variation after baking in 600℃is under 0.2g/cm~3. The core has resistance to water, so it can be dewaxed by hot water or steam.Systematic strength testing of core after baking have been carried out, such as: unstrengthened strength, strengthened strength and residual strength. Strength performance of JXR materials have been compared, which have been mixed with different slurry mixing liquid. Systematic research has been carried out, including: slurry fluidity and suspending stability, strength after baking, high temperature stability and residual strength of the filled material. JX-2 and JXR-2 have been compared with JXR-3 which has been optimized for filling function. The result shows that, when mixed with silica sol or phosphoric acid solution, strength of core is superior to the one which mixed with water. Strength of core become higher with the increase of concentration of phosphoric acid solution. But phosphoric acid solution will impact slurry fluidity and self-setting. Silica sol is recommended in actual production when it doesn't need special strength. When slurry flow ability is high enough to satisfy filling function, the performance of JXR-3 is superior to JX-2 and JXR-2. JXR-3 has enough bench time and suspending stability, high strength after baking and good high temperature stability. Three kinds of slurry mixing liquid, water, silica sol and phosphoric acid solution have been compared and evaluated, and it is concluded that silica sol is the best.Based on easy to demould characteristic of phosphate self-setting material, further application in investment casting has been investigated. To verify its practicability, we try to cast centrifugal & multiple-vane impeller, the core of it is difficult to demould. Because the casting have twisted blade, ceramic core can't demould in conventional hot-pressing process. To solve mentioned above technical problem, we use JXR series phosphate self-setting material to form the impeller core. To avoid casting swelling and metal-leaking defects in the internal cavity of an investment casting, systematic research has been carried out, on technologic aspects that using the JX and JXR series phosphate self-setting material slurry to fill up the narrow cavity of shell molds. The actual casting making process shows that JXR material can be used in forming the cores of casting with low cost, which partial have complex shape and narrow cavity. Because it have good slurry flow ability, JXR-3 material is fit for filling up the narrow cavity of shell molds, can make a decisive effect to avoid casting swelling and metal-leaking defects.Actual cast product experiment shows that the forming technics of phosphate self-setting & formed by pouring materials is feasible. It easy to operate, doesn't require special equipment, can be used in making all kinds of complex core and filling up shell molds with low cost. It have great application prospect.
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