55results about How to "Reduce residual strength" patented technology

The present invention discloses a silicon sol adhesive modified by using high polymer and its preparation method. Its composition comprises alkaline silicon sol containing 20-30%, SiO2 and PVA whose content is less than [(32-100XSiO2%) / 320]X100%. Its preparation method includes: a. preparing PVA aqueous solution; b. preparing alkaline silicon sol solution; and c. mixing said two solution uniformly, in which after the alkaline silicon sol solution is prepared or after the two solutions are mixed uniformly its pH value must be regulated. Said silicon sol adhesive can accelerate drying speed when it is used in investment casting industry, and can raise the normal temp. strength of pattern shell in the investment casting, and can reduce retained strength.

The invention relates to a preparation method of a fiber reinforced compound silica sol shell for investment casting, which aims to solve the problem that a shell preparedin the prior art is low in humidity and strength, and comprises the sequential steps as follows: 1), surface layer coating preparation; 2), surface layer shell preparation; 3) transition layer coating and shell preparation; 4) back layer coating preparation, that is, adding mullite powder into silica sol according to the mass ratio of (2.2-3.0):1 of the fireproof mullite powder to the silica sol in the back layer coating, so that paste-shaped coating is obtained, and agitating; adding polypropylene fiber which is 0.4 percent-2.0 percent of the fireproof mullite powder in mass in the back layer coating into the agitated paste-shaped coating, enabling the polypropylene fiber to uniformly disperse, adding the silica sol once again so as to lower the mass ratio of the mullite powder to the silicon sol to (1.1-1.5):1, and continuously agitating the mixture for 2 h for stand-by application; selecting the polypropylene fiber with the diameter of Phi 30 mum-Phi 50 mum and length of 2mm-6mm; 5) back layer shell preparation; 6) slurry sealing; 7) calcination, cooling and tapping off. The preparation method has the advantages that the shell is high in humidity and strength, and low in shell residual strength; the high-temperature air permeability is not affected after the fiber is burned at a high temperature; the effect of improving metal liquid mold-filling capacity to a certain degree is achieved; the number of coating and smearing layers is decreased; the production efficiency is improved.

The invention discloses a high-performance investment casting mould shell, and relates to the technical field of casting. A manufacturing method for the high-performance investment casting mould comprises the following steps of: (1) uniformly mixing 500-mesh quartz sand, rare earth, an ethyl silicate-rosin complexing agent and activated bentonite to obtain a mixture I, adding the mixture I into a high-speed stirrer to stir, thereby obtaining mould shell inner-layer slurry; mixing 200-mesh quartz sand, the ethyl silicate-rosin complexing agent and activated bentonite to obtain a mixture II, adding the mixture II into a high-speed stirrer, and stirring to obtain mould shell outer-layer slurry; (2) uniformly coating the mould shell inner-layer slurry to the surface of a wax mould, drying, and uniformly coating the mould shell outer-layer slurry, thereby obtaining a coated wax mould; (3) uniformly bundling the surface of the coated wax mould by an iron wire; and (4) putting the coated wax mould at a high temperature to perform wax melting treatment, and completely melting the wax mould to obtain the needed casting mould shell. The manufactured investment casting mould shell can cast a cast piece with higher precision and surface roughness, is high in high temperature resistance and strength, and is low in retained strength.

A silica sol adhesive for the investment casting is proportionally prepared from the simple silica sol and the ion-exchanging silica sol through mixing.