1．Physicochemical Property：
Water solubility: insoluble
Density: 5.21
Melting point: 2435℃ Boiling point: 4000℃
Molecular weight: 151.99 EINECS RN: 215-160-9
English name: Chromium oxide
2．Chemical Property
It is soluble in hot alkali metal bromate solution, and insoluble in water, alcohol, acid and alkali. And it is extremely stable to the light, the atmosphere, high temperature and corrosive gases such as sulfur dioxide and hydrogen sulfide. It has a high hiding power, and it is poisonous.
Heating with oxides of many divalent metals to a high temperature can form a spinel type compound.
It has α-Al₂O₃ structure. Cr₂O₃ possesses very good stability to acid and alkali, and generally it does not react with acid and alkali. Trivalent chromium hydroxide, Cr (OH)₃ is amphoteric, which can react with acid and alkali.
Cauterant Cr₂O₃ has dense crystal, similar to corundum and insoluble in acid, but it can be melted into a soluble salt. For instance, Cr₂O₃ and potassium pyrosulfate react at high temperatures:
Cr₂O₃+ 3K₂S₂O7 =3K₂SO₄+ Cr₂(SO₄)₃
3．Functions and Uses
It is primarily used in smelting chromium metal and chromium carbide, serving as coloring agent of enamel, ceramics, artificial leather and building materials, the organic chemical compound catalyst, sun-proof coating, abrasive substance and green polishing paste as well as special purpose printing ink for printing paper currency. In addition, it is also used in production of refractory matters such as high-chrome brick and chrome corundum brick
4．Preparation Methods
(1)Oxidation-reduction method
Potassium dichromate and sulphur are mixed to realize reduction reaction, and it is obtained after wet-grinding, washing with hot water, filter pressing, drying and smashing.
K₂Cr₂O7 + S == K2SO₄ + Cr₂O₃
(2)Chromium trioxide decomposition method
Chromic anhydride may be used to achieve thermal decomposition at 1100℃, and it is obtained after cooling and high-speed crushing.
4CrO₃ =1100°C= 2Cr₂O₃ + 3O₂↑
(3)Chromic hydroxide decomposition method
Or chromic hydroxide experiences thermal decomposition at high-temperature, and it is obtained after washing, drying and crushing.
2Cr(OH)₃ =△= Cr₂O₃ + 3H₂O
(NH₄)₂Cr₂O7 == N₂↑ + Cr₂O₃ + 4H₂O
(4)Ammonium dichromate decomposition method
(NH₄)₂Cr₂O7 == N₂↑ + Cr₂O₃ + 4H₂O
5．Hazardous Characteristics
It is a strong oxidant that can cause severe reaction and even combustion when it contacts flammable materials such as benzene and combustibles such as sugars and cellulose. When it is mixed with the reductive substances such as magnesium powder, aluminum powder, sulfur and phosphor, it will cause combustion or explosion in case they rub or hit each other, and it has relatively strong corrosivity.
6．Emergency Treatment
Contact with skin: using soap to wash it with water for 5 minutes.
Contact with eye: using a large amount of water to wash it for at least 15 minutes; seeking medical advice.
Inhalation: Move the patient to a place with fresh air, performing oxygen therapy or artificial respiration.
Emergency processing of the leakage of chromium sesquioxide: It is necessary to wear safety device and enter the site; Using a simple method to collect the leaked powder and put them into closed containers.
Matters needing attention in storage: Store it in closed containers, and put them at cool and ventilated place or the specified sites; tabu matters shall be avoided.
7．Product Classification
Chrome oxide green used for grease-type abrasive substance
Pigment grade chrome oxide green
Chrome oxide green used for metal surface treatment
Catalyzing grade chrome oxide green
8. Fields
Smelting and Military Industry
Dyeing and Pigment
Electroplating and Anticorrosion
Chemical Materials
New Energy New Products
