| Molecular Formula | [Sr-Ca]Cr2O4 |
| Physical and Chemical Properties | Chemical Properties Strontium Calcium Yellow is a lattice-doped pigment that quantitatively incorporates calcium ions into the strontium chromate lattice. Its appearance is a soft powder with light lemon yellow. Slightly soluble in water, soluble in hydrochloric acid, nitric acid, acetic acid and ammonia. Good heat resistance, above 600 ℃. Medium light resistance, low tinting power, low hiding power, excellent rust resistance. Non-flammable, tasteless, toxic. |
| Use | Applications can be used as a variety of metal surface anti-corrosion coatings. When it is used on the surface of steel, only 1% ~ 3% of the total solid content of the coating can be added to double the rust resistance of the coating film. The post-treated strontium calcium yellow is applied to the electrophoretic paint on the surface of aluminum and aluminum alloy, which can not only improve the rust resistance of the electrophoretic coating film by more than one time, but also improve the swimming coating force. Also used in powder coatings, to achieve heavy corrosion effect. |
One Step. Strontium carbonate is directly used as raw material to produce strontium calcium yellow. Reaction equation:
mSrCO3 nCaCo3 (m n)H2CrO4→(mSr·nCa)CrO4 (m n)CO2↑
Where, m:n = 10:1~20:1, m n = 1
Operation method: put a certain molar ratio of strontium carbonate and calcium carbonate into a synthesis kettle with added bottom water (or mother liquor) and stir, raise the temperature to boiling, add hot chromic acid, and immediately produce light yellow precipitate. As the reaction progresses, the color of the reaction solution changes from light yellow & rarr; Light yellow & rarr; Positive yellow & rarr; Orange. During the reaction process, pay attention to control the pH value to 5~6, and the pH value at the end of the reaction drops rapidly. Immediately stop adding acid and adding water to cool, then filter and wash with water, dry the filter cake at 120 ℃, send it to 600 ℃ brick kiln or reverberatory furnace for calcination for 1~2h, discharge and cool, and then crush the product through surface treatment. The molar ratio of strontium carbonate to calcium carbonate used in the production of raw materials can be controlled between 20:1 and 10:1, but whether calcium ions can be truly doped into the strontium chromate lattice in the reaction, the reaction speed and crystallization conditions must be strictly controlled. The synthetic mother liquor contains a large amount of hexavalent chromium ions, which can be recycled, and the available acid can also be directly pumped into the synthesis kettle as bottom water. After the mother liquor is circulated for dozens of times, when the accumulated impurities are too large to affect the product quality, it can be injected into the mother liquor treatment tank and reduced by reducing the hexavalent chromium ions (such as sodium sulfide, sodium sulfite, etc.), then caustic soda is added to neutralize and recover chromium oxide, and the mother liquor meets the discharge standard.