The choice of water-based binder for shell molds of the investment casting of titanium alloys

The paper presents the studies of influence of various water-base binders, viz. EHT Binder (USA), Remasol (UK), Armosil of different modifications (Russia) on physical and mechanical properties of shell molds and alpha layer depth. The most perspective binders for casting of titanium alloys are defined. Data on interaction of the ASD-4 powder with water binders are obtained and recommendations of its percentage ratio for obtaining optimum properties are given. All ceramic slurries were prepared by the same technology. The binder and filler were added to the mixer, stirred until homogeneous mixture of desired viscosity was obtained, and then the coating was formed by layering with a modeling unit. Dusting of units was carried out according to existing mass production technology. In order to improve the strength characteristics of shell molds fine powder of aluminum ASD-4 was added to the slurry in an amount of 7.5 % of the filler weight. Alpha layer depth was determined by microstructural analysis. Microsections were made from samples with access to the surface under investigation. Pieces for macro- and microsections were cut using abrasive wheels with a cooling environment. On the basis of studies a technological instruction on making shell molds based on Remasol, Remаsol with 5 % ASD-4, Armosil and Armosil AM with 5 % ASD-4 binders is developed.