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 discloses a composite sodium silicate binder for sand mold and a preparing method thereof. The composite sodium silicate binder is formed by the following components in parts by weight: 100 parts of sodium silicate, 5-10 parts of straw powder paste and 0.5 to 2 parts of water. The preparing method thereof comprises the steps of: 1. drying, crushing and subjecting straws to a sieve not less than 325 meshes in order to obtain the straw powder paste; 2. adding 5-10 parts by weight of the straw powder paste obtained in the step 1 with 0.5 to 2 parts by weight of water, followed by uniform stirring to further obtain wet straw powder paste; and (3) adding the wet straw powder paste with 100 parts by weight of sodium silicate. The composite sodium silicate binder manufactured according to the method solves the problem that the silicate binder is poor in sand mold collapsibility and difficult in recycling when being used as binder; in addition, compared with other methods for improving the sand mold collapsibility of silicate binder, the method according to the invention, in which inexpensive straw is taken as raw material, lowers the cost of sand mold (core) dramatically.

The invention discloses a CO2 hard sodium silicate sand additive; wherein, the mass proportion of each component is: 1 to 5 percent of PEO, 10 to 35 percent of starch sugar, 25 to 50 percent of carbonate and 25 to 40 percent of water; the molecular weight of the PEO is 1*10<5> to 9*10<5>. The starch sugar is selected from dextrose, maltose or malt extract; the carbonate is selected from chalk, limestone or calcium carbonate. The invention also provides a sanding mixing technique of casting sand mixture which uses the CO2 hard sodium silicate sand additive. The CO2 hard sodium silicate sand additive of the invention can effectively reduce the content of the sodium silicate sand in the sand mixture as well as maintains higher sand mixture intensity and better old sand collapsihility. The sodium silicate sand prepared by using the additive is not sensitive to the overblowing of CO2, is easy to control the hard technique and has the higher humidity resistance.

The invention discloses a ceramic shell material for precision casting of superalloy castings and a preparation method of the ceramic shell material. A clean and dry blade wax pattern module is immersed into a surface layer coating; after the coating is uniformly coated on the surface of a wax pattern, zircon sand or fused corundum sand serving as fire resistant filler is uniformly spread; dryingis performed at room temperature; then, after a back layer coating of the module is stained with slurry, sintered mullite sand serving as fire resistant filler is uniformly spread and fully dried; theback layer coating is repeatedly stained with the slurry until a required thickness of a shell is achieved; then the back layer coating is used for slurry sealing and drying; the dried shell is dewaxed in a high-pressure steam dewaxing kettle; roasting is performed in air at 850-1100 DEG C for 2-6 hours; and the ceramic shell is obtained after air cooling to the room temperature. The shell manufactured according to the preparation method has high wet strength, high-temperature strength, low residual strength, excellent air permeability, excellent deformability, and excellent collapsibility. Compared with a common shell, the shell is decreased in coating frequency of back layers and reduced in thickness. The increase in heat dissipation rate during casting solidification cooling is facilitated, and the metallurgical quality of the castings is improved.

A method for producing stacks (1) of individual web sections (2; 3), such as tissue web sections from a continuous web of material (2a; 2b), comprises the steps: (a) directing the continuous web (2a; 2b) to a perforating station (27); (b) perforating the continuous web (2a; 2b) at predetermined intervals and forming sheets (5) of web material between consecutive perforation lines (4) extending laterally across the continuous web (2a; 2b), the perforating being carried out by means of at least one perforation element (26) arranged at the circumference of a perforation roller (24); (c) directing the continuous web (2a; 2b) to a cutting station (31; (d) cutting at second predetermined intervals the continuous web (2a; 2b) into web sections (2; 3) by means of a cutting element (38) acting against an anvil element (37), in order to generate a clear cut or a tab-bond; (e) folding the web sections (2; 3) by means of a folding roll (32); and (f) stacking the folded web section (2; 3) to generate a stack (1) of folded sheets.

The invention discloses a shell making process of a silica sol shell with high deshelling property. The shell making process comprises the following steps: S1, uniformly mixing powder with silica solwith stirring, and adding a wetting agent and a defoamer to form a first mixture; S2, immersing a wax mold into the first mixture, taking the wax mold out, scattering sand into the wax mold, and drying to obtain a first-layer mold shell; S3, repeating the step S2 until second to sixth layers of mold shells are obtained; S4, drying the wax mold including the first to sixth layers of mold shells tocomplete sealing; S5, calcining the wax mold including the first to sixth layers of mold shells to obtain a mold shell casting. According to the shell making process of the silica sol shell with highdeshelling property disclosed by the invention, fully-calcined aluminosilicate refractory sand powder, free iron and hard kaolinite with low diaspore content is taken as a main material of the silicasol shell, and is combined skillfully with quartz sand, so that the high-temperature strength of the mold shell is ensured, and the retained strength after mold shell pouring can be lowered greatly.

The invention discloses a device and a method for preparing a fiber reinforced silica sol composite shell through airflow laying. The device comprises a fiber laying chamber, a fiber storage chamber,an air supply unit and a support, wherein the fiber laying chamber is a hollow cube and is composed of four side vertical plates and an upper bottom surface exhaust hole plate and an upper bottom surface exhaust hole plate, and an exhaust hole is formed in the upper bottom surface exhaust hole plate; a rotating shaft used for bearing the shell sample is installed in the fiber laying chamber; the fiber storage chamber is of a hollow inverted quadrangular frustum shape formed by four side plates and a lower bottom surface air inlet plate, a fiber storage rack is arranged in the fiber storage chamber, and airflow guide holes are formed in the fiber storage rack; and the fiber spreading chamber is located right above the fiber storage chamber, the side length of the side vertical plate of thefiber spreading chamber is equal to the side length of the side plate of the fiber storage chamber, and the four side vertical plates and the four side plates are fixedly connected in a one-to-one correspondence manner. According to the device and the method, the fibers can be uniformly distributed in the shell, the fibers can be laid on the shell in a quantitative mode, so that the performance ofthe prepared shell is consistent, and the fiber with the large length-diameter ratio can also be added into the shell.

The invention discloses a method for changing strength of a shell by impregnating with an organic binder. An impregnating solution adopts 0.5-4 wt% of a PVA solution, 2-20 wt% of a latex solution or a liquid with preset viscosity. Impregnation time is 2-10 min. impregnation is carried out layer by layer, every few layers or only at a slurry seal layer. After the shell is dried, the next layer of shell is continuously prepared, or dewaxing is conducted after the slurry seal layer is impregnated and dried. The method provided by the invention has high reliability and is simple to operate. Through adjusting type and concentration of the impregnating solution and number of impregnation layers, strength performance of shells made of various materials can be conveniently changed. Through impregnation, layer strength is increased; normal temperature strength of the shell is raised; dewaxing crack resistance is enhanced; combination of front and rear impregnated layers is weakened; retained strength is reduced; shelling performance is improved; and the problem that strength of a mould investment casting shell is hard to coordinate and control is solved.

The invention discloses modified inorganic binder sand with collapsibility. The modified inorganic binder sand comprises silica sand, a modified inorganic binder and a powder collapsibility agent, the modified inorganic binder comprises an inorganic binder and a modifier, the inorganic binder is a binder based on silicate, and the modifier comprises phosphate, borate and meta-aluminate and is used for modifying the inorganic binder; the powder collapsing agent is a mixture of inorganic salts and organic powder; comprising the following substances in parts by weight: 100 parts of silica sand, 2-5 parts of a modified inorganic binder and 1-3 parts of a powder collapsing agent, the collapsibility modifier is added in the modification process of the inorganic binder, and the powder collapsibility agent is added in the sand mixing process, so that the collapsibility of the inorganic binder type sand is remarkably improved, the residual strength of an inorganic binder sand mold is greatly reduced after pouring, a casting is easy to clean, the casting can be easily stripped from the molding sand, sand cleaning is facilitated, and the labor intensity of workers is reduced.

The invention discloses a gypsum shell low in retained strength and a preparing method of the gypsum shell. Gelatin is contained in the gypsum shell. The method comprises the steps that gypsum powderand filler are evenly mixed; after water is heated, the gelatin is added in the water, uniform mixing is conducted, and a transparent solution is obtained; gypsum powder and filler mixed powder is added in the transparent solution, and slurry is obtained; the slurry is poured into a die; after the slurry in the die is hardened, the die is dismounted, standing is conducted at the room temperature,and a wet gypsum shell is obtained; and the wet gypsum shell is naturally dried and roasted, and the gypsum shell low in retained strength is obtained. The gypsum shell is low in retained strength andeasy to clean, the preparing method is simple, and the production efficiency is high.

The invention discloses in-situ polymerization-modified silica sol. The in-situ polymerization-modified silica sol comprises alkaline silica sol and PVP obtained by in-situ polymerization. The in-situ polymerization-modified silica sol has the advantages of resource saving, low cost, popularization adaptability, less change of SiO2 content before and after modification, obvious improvement of modified silica sol viscosity, excellent interaction and performances between PVP and SiO2 in the silica sol, controllable modification degree and extensive applicability. The preparation method comprises the following steps of 1, uniformly dispersing a PVP monomer NVP in silica sol to obtain a mixture A, 2, dispersing an initiator in the mixture A to obtain a reaction system B, and 3, continuously stirring the reaction system B for a reaction lasting for 4-5h at a constant temperature of 90-100 DEG C to obtain modified silica sol. The preparation method has simple and convenient processes, realizes uniform dispersion of NVP in the silica sol by silica sol water as a solvent and in-situ polymerization on SiO2, and saves time and labor.

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 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.

The invention discloses a silica sol binder for a shell. The silica sol binder comprises the following components in percentage by mass: 85-90% of alkaline silica sol, 0.6-1.2% of mesoporous silica nanospheres, 0.1-0.2% of calcium hydroxide, 0.3-0.5% of nano-crystalline cellulose, 0.15-0.25% of a dispersing auxiliary and the balance of water, wherein the dispersing auxiliary comprises sodium hexametaphosphate, poly(ethylene glycol) methyl ether-2000 and triethanolamine. The silica sol binder has higher drying speed, can shorten the interlayer drying time, improves the production efficiency ofthe shell, is short in shell manufacturing period and high in shell manufacturing efficiency, can improve the normal temperature strength of the shell, and is low in residual strength, easy to clean and suitable for producing castings with complicated geometrical shapes.