Zinc phosphate

Chemical compound From Wikipedia, the free encyclopedia

Zinc phosphate is an inorganic compound with the formula Zn3(PO4)2. This white powder is widely used as a corrosion resistant coating on metal surfaces either as part of an electroplating process or applied as a primer pigment (see also red lead). It has largely displaced toxic materials based on lead or chromium, and by 2006 it had become the most commonly used corrosion inhibitor.[2][3] Zinc phosphate coats better on a crystalline structure than bare metal, so a seeding agent is often used as a pre-treatment. One common pre-treatment agent is sodium pyrophosphate.[4]

Quick facts Names, Identifiers ...
Zinc phosphate
Zinc phosphate
Zinc phosphate
Names
IUPAC name
Zinc phosphate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.040 Edit this at Wikidata
RTECS number
  • TD0590000
UNII
  • InChI=1S/2H3O4P.3Zn/c2*1-5(2,3)4;;;/h2*(H3,1,2,3,4);;;/q;;3*+2/p-6 checkY
    Key: LRXTYHSAJDENHV-UHFFFAOYSA-H checkY
  • InChI=1/2H3O4P.3Zn/c2*1-5(2,3)4;;;/h2*(H3,1,2,3,4);;;/q;;3*+2/p-6
    Key: LRXTYHSAJDENHV-CYFPFDDLAR
  • [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])(=O)[O-].[O-]P([O-])([O-])=O
Properties[1]
  • Zn3(PO4)2 (anhydrous)
  • Zn3(PO4)2·4H2O (tetrahydrate)
Molar mass
  • 386.17 g⋅mol−1 (anhydrous)
  • 458.231 g⋅mol−1 (tetrahydrate)
Appearance
  • white monoclinic crystals
  • colorless orthorhombic crystals
Density 4.0 g/cm3
Melting point 900 °C (1,650 °F; 1,170 K)
insoluble
−141.0×10−6 cm3/mol
1.595
Structure
monoclinic
Thermochemistry
−2891.2 ± 3.3
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
Flash point Non-flammable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Minerals

Natural forms of zinc phosphate include minerals hopeite and parahopeite. A somewhat similar mineral is natural hydrous zinc phosphate called tarbuttite, Zn2(PO4)(OH). Both are known from oxidation zones of Zn ore beds and were formed through oxidation of sphalerite by the presence of phosphate-rich solutions. The anhydrous form has not yet been found naturally.

Use

Dentistry

Zinc phosphate cement is the classically used dental cement. It is commonly used for luting permanent metal and zirconium dioxide restorations and as a base for other dental restorations. Zinc phosphate cement is used for cementation of inlays, crowns, bridges, and other orthodontic appliances and occasionally as a temporary restoration.

References

External links

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