A fluoride-free continuous casting mold flux for ultralow carbon steel, comprising the following components in weight percentage: 3-10% of Na.sub.2O, 0-3% of Li.sub.2O, 3-8% of MgO, 5-15% of MnO, 0-8% of BaO, 4-12% of Al.sub.2O.sub.3, and impurities with a content of no more than 2%, the balance being CaO and SiO.sub.2, wherein the ratio of CaO/SiO.sub.2 is 0.8-1.3; the raw materials are mixed and then pre-melted; the pre-melted mold flux requires micro-adjusting according to the component deviation, and the ratio of the pre-melted material is not lower than 70%; then a carbonaceous material of 1-3% by the total weight of the mold flux is added and mixed so as to obtain the finished product mold flux. Said mold flux has a melting point of 1100-1200 C. and a viscosity of 0.2-0.6 Pa.Math.s at 1300 C. A method for preparing a mold flux comprising the following steps: mixing raw materials, pre-melting to obtain a pre-melt; then continuously supplementing raw materials into the pre-melt to obtain a substrate with a desired composition; then adding a carbonaceous material to the substrate and mixing so as to obtain said mold flux. This mold flux is a boron-free and fluoride-free mold flux, can effectively reduce the inclusion defect of blank casting and increase the yield of blank casting.

A fluoride-free continuous casting mold flux for ultralow carbon steel, comprising the following components in weight percentage: 3-10% of Na.sub.2O, 0-3% of Li.sub.2O, 3-8% of MgO, 5-15% of MnO, 0-8% of BaO, 4-12% of Al.sub.2O.sub.3, and impurities with a content of no more than 2%, the balance being CaO and SiO.sub.2, wherein the ratio of CaO/SiO.sub.2 is 0.8-1.3; the raw materials are mixed and then pre-melted; the pre-melted mold flux requires micro-adjusting according to the component deviation, and the ratio of the pre-melted material is not lower than 70%; then a carbonaceous material of 1-3% by the total weight of the mold flux is added and mixed so as to obtain the finished product mold flux. Said mold flux has a melting point of 1100-1200 C. and a viscosity of 0.2-0.6 Pa.Math.s at 1300 C. A method for preparing a mold flux comprising the following steps: mixing raw materials, pre-melting to obtain a pre-melt; then continuously supplementing raw materials into the pre-melt to obtain a substrate with a desired composition; then adding a carbonaceous material to the substrate and mixing so as to obtain said mold flux. This mold flux is a boron-free and fluoride-free mold flux, can effectively reduce the inclusion defect of blank casting and increase the yield of blank casting.

A ceramic core is obtained by firing a mixture that contains 0.1-15.0% by mass of alumina and 0.005-0.1% by mass of potassium and/or sodium with the balance made up of silica and unavoidable impurities. Not less than 90% by mass of amorphous silica is contained in 100% by mass of the silica. A method for producing a ceramic core, wherein: a blended material is obtained by blending 25-45% by volume of a binder into 55-75% by volume of a mixture that is obtained by mixing alumina, potassium and/or sodium, and silica so as to have the above-mentioned composition; the blended material is injected into a die so as to obtain a molded body; and the molded body is degreased at 500-600 C. for 1-10 hours, and then fired at 1,200-1,400 C. for 1-10 hours.

A ceramic core is obtained by firing a mixture that contains 0.1-15.0% by mass of alumina and 0.005-0.1% by mass of potassium and/or sodium with the balance made up of silica and unavoidable impurities. Not less than 90% by mass of amorphous silica is contained in 100% by mass of the silica. A method for producing a ceramic core, wherein: a blended material is obtained by blending 25-45% by volume of a binder into 55-75% by volume of a mixture that is obtained by mixing alumina, potassium and/or sodium, and silica so as to have the above-mentioned composition; the blended material is injected into a die so as to obtain a molded body; and the molded body is degreased at 500-600 C. for 1-10 hours, and then fired at 1,200-1,400 C. for 1-10 hours.

An investment casting method involves producing a casting shell by applying a hardenable refractory material to a sacrificial pattern. The casting shell having a plurality of phosphate bonds in the hardenable refractory material, which provide increased structural integrity during casting and improved frangibility during shell removal. The casting shell may also have a plurality of gaseous pockets suspended in the refractory material, which do not degrade the structural integrity during casting and provide improved frangibility during shell removal.

An investment casting method involves producing a casting shell by applying a hardenable refractory material to a sacrificial pattern. The casting shell having a plurality of phosphate bonds in the hardenable refractory material, which provide increased structural integrity during casting and improved frangibility during shell removal. The casting shell may also have a plurality of gaseous pockets suspended in the refractory material, which do not degrade the structural integrity during casting and provide improved frangibility during shell removal.

A composition for making a core for use in a moulding or casting process, a core comprising said composition, and a mould for producing an article by high pressure die casting or semi-solid casting. The composition comprises a particulate refractory material, a binder composition comprising at least one hydrophilic polymer, comprising at least one polysaccharide or polysaccharide derivative; and at least one pozzolanic additive. The mould comprises a core for defining an internal cavity of the article and the core comprises a solidified core composition. The solidified core composition comprises a particulate refractory material and a binder composition, degrades in water such that a cylinder of the solidified core composition having a maximum height of 80 mm and a maximum diameter of 50 mm disintegrates in no more than 10 minutes when immersed in water at a temperature of 20 C. and stirred at a speed of 60 rpm, and has a flexural strength of at least 300 N/cm.sup.2. The invention also resides in a method for producing an article by high pressure die casting or semi-solid casting.

A composition for making a core for use in a moulding or casting process, a core comprising said composition, and a mould for producing an article by high pressure die casting or semi-solid casting. The composition comprises a particulate refractory material, a binder composition comprising at least one hydrophilic polymer, comprising at least one polysaccharide or polysaccharide derivative; and at least one pozzolanic additive. The mould comprises a core for defining an internal cavity of the article and the core comprises a solidified core composition. The solidified core composition comprises a particulate refractory material and a binder composition, degrades in water such that a cylinder of the solidified core composition having a maximum height of 80 mm and a maximum diameter of 50 mm disintegrates in no more than 10 minutes when immersed in water at a temperature of 20 C. and stirred at a speed of 60 rpm, and has a flexural strength of at least 300 N/cm.sup.2. The invention also resides in a method for producing an article by high pressure die casting or semi-solid casting.

The disclosure concerns printable refractory compositions, more particularly ceramic-based pastes for 3D printing of molds for additive metal casting. In particular, the present disclosure concerns composition for forming mold regions having controlled thermal conductivity and dissipation and controlled release of gaseous products therefrom during heating to mitigate mechanical failure risks in an additive casting process of metal objects.

The disclosure concerns printable refractory compositions, more particularly ceramic-based pastes for 3D printing of molds for additive metal casting. In particular, the present disclosure concerns composition for forming mold regions having controlled thermal conductivity and dissipation and controlled release of gaseous products therefrom during heating to mitigate mechanical failure risks in an additive casting process of metal objects.