Water Quality Requirements For Porcelain Enamel
Although about 30% of water is added in the process of preparing enamel slurry, people generally do not regard water as a raw material. Another major consumer is the pretreatment of iron billets. For these two purposes, water quality The requirements are quite different.
1. Water for pretreatment of steel body
After each pretreatment process is completed, it must be rinsed with water. The task of water rinse is to rinse off various emulsified and saponified grease, oil and salt. During the water rinse process, no chemical reaction between the pretreatment body and the rinse water is allowed. To achieve this, the water used must be free of alkaline earth metal ions. The percentage of alkaline earth metal ions in the water is expressed by the hardness of the water. For the hardness of the water, we can ask the water supplier to ensure that the coating For the quality of the product, we recommend using decationized water.
2. Water used to prepare enamel slurry
On the earth, water is the most widely used solvent. In general, the purer the water, the stronger the tendency for it to absorb ions. In the process of preparing enamel slurry, this dissolution behavior is not ideal, and it will aggravate alkali evolution of enamel frit. Too much alkali metal ion content in the enamel slurry will affect the retention performance of the clay. Due to the continuous precipitation of alkali ions, it will be difficult to control the rheological properties of the enamel slurry. In the ball milling process, add harder The amount of water, clay and retention agent can be reduced. In order to stabilize the calcium content in the water during the ball milling process, people add an aqueous solution of calcium silicate and adjust it to 35°GH (German hardness), which is a saturated concentration.
The water hardness units and their conversion factors in different countries are as follows:
Mval/kg = 28 mg CaO or 50 mg CaCO3 per 1000 ml of water
Germany 1°GH = German water hardness = 10 mg CaO per 100 ml of water
1°GH=1.78°FH (French water hardness)=1.25°BH (British water hardness)=17.8ppm=0.357mval/kg
France 1°FH = French water hardness = 10 mg CaCO3 per 1000 ml of water
UK 1°BH=British water hardness=1g of CaCO3 per gallon of water=14.3mg of CaCO3 per 1000ml of water
U.S. ppm = parts per million = 1 mg of CaCO3 per 1000 ml of water