Can water glass investment casting produce stainless steel parts

Water Silicate Investment Casting Can Produce Stainless Steel Parts] Water Silicate Investment Casting Can Produce Stainless Steel Parts, Stainless Steel Parts with Low Dimensional Accuracy and Surface Finish Requirements for Casting Castings.

It can be used to cast special steel, alloy cast steel to meet special needs, there are many varieties, usually containing one or more high-volume alloying elements to obtain a certain special property. For example, high-manganese steel containing 11% 14 manganese can withstand impact wear and is mostly used for rust-resistant parts of mining machinery and construction machinery; A variety of stainless steels with chromium or chromium-nickel as the main alloying element are used for parts that work under corrosive or high temperature conditions above 650 °C, such as valve bodies, pumps, containers for chemical applications, or steam turbine housings for large-capacity power stations.

Investment casting, also known as lost-wax casting, includes wax pressing, wax repairing, tree formation, slurry, wax melting, casting molten metal and post-treatment processes. Lost wax casting is to use wax to make a wax model of the parts to be cast, and then the wax model is coated with mud, which is the clay mold. After the clay mold is dried, it is then roasted into a pottery mold.

Once roasted, all the wax molds melted down and lost, leaving only the pottery molds. Generally, when making mud molds, the pouring port is left, and then the metal melt is poured from the pouring port, and after cooling, the required parts are made.

Water glass investment casting] is the use of water glass as the adhesive of investment casting, the most common binder used in investment casting is silicate colloidal solution (referred to as silicate sol), such as ethyl silicate hydrolysate, water glass and silica sol. The substances that make them up are mainly silicic acid (H2SiO3) and solvents, and sometimes stabilizers such as NaOH in silica sol. Ethyl silicate hydrolysate is the earliest and most common binder used in silicate sol mold casting obtained by hydrolysis of ethyl silicate. The water glass shell type is easy to deform and crack, and the dimensional accuracy and surface finish of the castings poured with it are poor.

However, in China, when the production of carbon steel castings with higher precision requirements and non-ferrous alloy castings with lower melting points, water glass is still widely used in production; The stability of silica sol is good, it can be stored for a long time, and there is no need for special hardening agent when making the shell, but the wetting of the silica sol to the investment mold is slightly poor, and the hardening process of the mold shell is a drying process that takes a long time.

So there are two basic elements that need to be used for casting:

1.Qualified cavity - has a certain strength, can withstand the high temperature of liquid alloy; And it can ensure that the liquid alloy can fill the cavity.

2.Liquid alloys with acceptable composition and appropriate temperature.

The casting process is generally: sand mixing - compaction - trimming - closing the box - pouring (before smelting molten iron - inoculation treatment) - sand removal - cleaning the gating riser - shot blasting - grinding burrs - quality inspection - anti-rust treatment - warehousing.

The water glass you mentioned is used in the process of sand mixing. Generally, more raw materials used in casting are sand, and the sand cannot form a certain shape of the cavity, it needs to have a binder, so that the sand has the effect of cohesion. Water glass is an inorganic chemical binder used in casting production.

Water glass is a common name for various polysilicate aqueous solutions, including sodium water glass, potassium water glass, lithium water glass, etc., and sodium water glass is commonly used in casting. After sodium silicate is dissolved in water, it becomes a viscous liquid, which is what we often call sodium water glass.

The sand in casting can usually be reused after it has been shaken off.

The simple meaning of "water glass casting" is to add water glass to the modeling material (generally referred to as silica sand) in a certain proportion, after stirring, rolling and mixing for 6-8min to make "water glass sand", loaded into the mold, sand box blowing into CO2 gas, CO2 and water glass through chemical reaction to form silica gel to harden the water glass sand, through molding, boxing, pouring and other processes to complete the casting process.

Sand is mixed with glass as a binder, which needs to be cured with carbon dioxide.

It is more difficult, mainly because the sand powder used for water glass investment casting is generally quartz sand quartz powder, which reacts with the nickel in stainless steel, resulting in defects such as burrs sticking to sand that are not easy to clean.