An interlayer pre-cooling apparatus for a sand mold freezing printing includes a sand paving apparatus. The sand paving apparatus is located above a negative-pressure low-temperature forming chamber, and the sand paving apparatus includes several independent sand paving grooves, a hollow sand paving roller, a cooling chamber, a sand scraping plate, and an openable and closable baffle. The openable and closable baffle is rotationally arranged at a discharge port of each sand paving apparatus, and the openable and closable baffle is used for paving low temperature premixed sand on demand. The premixed molding sand is further cooled during the process of scraping and compacting low-temperature molding sand. When the apparatus is adopted for sand mold freezing 3D printing, the low temperature of the premixed molding sand is precisely controllable, which has great significance for realizing interlayer pre-cooling of the sand mold freezing printing.

An interlayer pre-cooling apparatus for a sand mold freezing printing includes a sand paving apparatus. The sand paving apparatus is located above a negative-pressure low-temperature forming chamber, and the sand paving apparatus includes several independent sand paving grooves, a hollow sand paving roller, a cooling chamber, a sand scraping plate, and an openable and closable baffle. The openable and closable baffle is rotationally arranged at a discharge port of each sand paving apparatus, and the openable and closable baffle is used for paving low temperature premixed sand on demand. The premixed molding sand is further cooled during the process of scraping and compacting low-temperature molding sand. When the apparatus is adopted for sand mold freezing 3D printing, the low temperature of the premixed molding sand is precisely controllable, which has great significance for realizing interlayer pre-cooling of the sand mold freezing printing.

The present invention describes the use of a coating composition, comprising an aqueous phase having a pH of at most 5 and one or more refractories, in the foundry industry and also coated, waterglass-bound foundry molding elements, especially foundry molds and/or foundry cores, which each comprise such an aforementioned coating composition. The invention further describes a method for producing a coated, waterglass-bound foundry molding element. The invention likewise describes a kit whose contents include an aforementioned coating composition, comprising aqueous acid and one or more refractories.

With excellent heat retention of molten metal and better productivity/work environment, regardless of low-speed or high-speed, the usable die lubricant for die casting will be provided. An aqueous die lubricant for die casting in which a phyllosilicate mineral is dispersed at a concentration of 0.005 wt % or more and less than 5 wt % and has a particle diameter of 0.1 μm or less during the dispersion.

The present invention relates to a dry refractory paint precursor composition comprising, 5 to 55 wt.-% mineral filler, 20 to 45 wt.-% glass frit comprising SiO.sub.2, Na.sub.2O, B.sub.2O.sub.3 and/or Al.sub.2O.sub.3, and 0.1 to 25 wt.-% of a binder selected from waterglass, cement and mixtures thereof, all based on the total weight of the composition. The invention further relates to refractory paints comprising said compositions, and to methods for preparing said paints.

The present invention relates to a dry refractory paint precursor composition comprising, 5 to 55 wt.-% mineral filler, 20 to 45 wt.-% glass frit comprising SiO.sub.2, Na.sub.2O, B.sub.2O.sub.3 and/or Al.sub.2O.sub.3, and 0.1 to 25 wt.-% of a binder selected from waterglass, cement and mixtures thereof, all based on the total weight of the composition. The invention further relates to refractory paints comprising said compositions, and to methods for preparing said paints.

The present invention refers to a stable sodium and iron silicate solution that has a weight ratio of SiO.sub.2 to Na.sub.2O from 1.5 to 2.5 and a total percentage of solids, expressed by the sum of SiO.sub.2 and Na.sub.2O, from 20% to 55%. Said solution also has a soluble iron content, expressed by Fe, from 0.1% to 7%, and a water content from 38% to 79.9%. The present invention also refers to the process for preparing said stable solution of sodium and iron silicate, which comprises the steps of: (a) providing a siliceous material containing iron; (b) submitting said siliceous material containing iron to a hydrothermal treatment with caustic soda under high temperature and controlled pressure; and (c) filtering said reacted solution to separate the reacted portion of the hydrothermal treatment from the unreacted portion. Additionally, the present invention refers to the uses of said stable sodium and iron silicate solution.

A low-pressure casting apparatus includes a core that together with a mold forms a cavity and a reduced-pressure dryer configured to dry the core under reduced pressure. The core is disposed in the mold, the molded is closed, the core is dried under reduced pressure, and thereafter the cavity is filled with molten metal.

The present invention provides a curing agent for casting a water glass, including an ester and an amorphous silicon dioxide obtained by a thermal decomposition of ZrSiO.sub.4; and the curing agent for casting the water glass does not contain water. According to the present invention, the curing agent for casting the water glass has a strong adhesion-enhancing effect and a long shelf life, and is easy to use.

A casting slurry for producing shell molds for casting parts includes a metal alloy, the slurry includes powder particles and a binder, the binder includes colloidal yttrium oxide, and the powder particles includes calcia-stabilized zirconia.