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 modified sodium silicate with inorganic nanoparticles and a preparation method thereof. The modified sodium silicate with the inorganic nanoparticles is mainly composed of the uniformly attached inorganic nanoparticles prepared by a hydrolysis precipitation method and ordinary sodium silicate. The specific preparation method mainly comprises the following steps that metal nitrate or metal chloride salt is dissolved by ethyl alcohol and then mixed with the sodium silicate, ultrasonic oscillation is carried out for 10-15 minutes to enable the mixture to be uniformly mixed, then stirring is carried out for 20-60 minutes at a water bath temperature of 40-60 DEG C, and then pH is adjusted to be 5-8 to obtain the modified sodium silicate with the inorganic nanoparticles which are uniformly mixed. According to the modified sodium silicate with the inorganic nanoparticles prepared by the method, the content of the sodium silicate in molding sand can be effectively reduced, so that the collapsibility of the sodium silicate sand is greatly improved; and the molding sand prepared by the modified sodium silicate with the inorganic nanoparticles also has good comprehensive high-temperature performance, the gas evolution of the molding sand is remarkably reduced, and the quality of a casting 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.

The invention relates to a collapsibility enhancer for sodium silicate-bonded sand. Raw material components of the collapsibility enhancer for the sodium silicate-bonded sand comprise silicon dioxide, alumina and graphene. The inventor creatively adopts a mixture of the silicon dioxide, the alumina and the graphene as the collapsibility enhancer; no organic matters are contained in the collapsibility enhancer, so that no combustible gases generate; more importantly, the situation that the sodium silicate-bonded sand which takes sodium silicate, potassium silicate and lithium silicate as main bodies and is used for casting is difficult to clean after the sodium silicate-bonded sand is cast can be greatly improved; the collapsibility of the sodium silicate-bonded sand is remarkably improved, and the strength of molding sand of the sodium silicate-bonded sand is obviously improved. According to the collapsibility enhancer disclosed by the invention, on the premise that the organic matters are not added and the gas evolution of a sand core is not improved, the collapsibility of an inorganic binder taking the sodium silicate-bonded sand as a main component is greatly improved, the retained strength of the inorganic binder is greatly reduced, and the strength of the sodium silicate-bonded sand is improved.

The invention provides polymer-modified silicasol which contains alkaline silicasol and polyvinyl pyrrolidone, wherein the weight percent of SiO2 in the alkaline silicasol in the polymer-modified silicasol is 20.0-36.0%, and the weight percent of the polyvinyl pyrrolidone in the polymer-modified silicasol is 0.1-5.0%. The preparation method comprises the following steps: (1) preparing a polyvinylpyrrolidone water solution; (2) preparing the alkaline silicasol; and (3) uniformly mixing the solutions prepared in step (1) and step (2) according to the required ratio to obtain the polymer-modified silicasol. The polymer-modified silicasol can obviously shorten the drying time of the investment casting shell-making interlayers, effectively increases the normal-temperature strength of a wax pattern shell, decreases the retained strength of the wax pattern shell without influencing the hot strength of the vax pattern shell, has the advantages of simple preparation method and low cost, and is applicable to popularization and application.

The present invention relates to a soft joint grey cast-iron pipe hot-mould centrifugal casting special-purpose adhering moulding material. It includes fire-resisting aggregate, bonding agent, suspension agent and water. The described fire-resisting aggregate includes diatomite powder, perlite powder, vermiculite powder and silica flour, and the described bonding agent and suspension agent include sodium base bentonite and sodium cellalose glycollate. Said invention also provides its preparation method and concrete steps.