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Zinc phosphate

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Zinc phosphate
Zinc phosphate
Names
IUPAC name Zinc phosphate
Identifiers
CAS Number
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.040 Edit this at Wikidata
PubChem CID
RTECS number
  • TD0590000
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/2H3O4P.3Zn/c2*1-5(2,3)4;;;/h2*(H3,1,2,3,4);;;/q;;3*+2/p-6Key: LRXTYHSAJDENHV-UHFFFAOYSA-H
  • InChI=1/2H3O4P.3Zn/c2*1-5(2,3)4;;;/h2*(H3,1,2,3,4);;;/q;;3*+2/p-6Key: LRXTYHSAJDENHV-CYFPFDDLAR
SMILES
  • ...P()(=O).P()()=O
Properties
Chemical formula H4O12P2Zn3
Molar mass 454.11 g·mol
Appearance white solid
Density 3.998 g/cm
Melting point 900 °C (1,650 °F; 1,170 K)
Boiling point 158 °C (316 °F; 431 K)
Solubility in water insoluble
Magnetic susceptibility (χ) −141.0·10

cm/mol

Refractive index (nD) 1.595
Structure
Crystal structure monoclinic
Thermochemistry
Std enthalpy of
formation (ΔfH298) 		− 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 , 100 kPa). checkY verify (what is  ?) Infobox references
Chemical compound

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. Zinc phosphate coats better on a crystalline structure than bare metal, so a seeding agent is often used as a pre-treatment. One common agent is sodium pyrophosphate.

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

It is prepared by mixing zinc oxide (ZnO) and magnesium oxide (MgO) powders with a liquid consisting principally of phosphoric acid, water, and buffers. It is the standard cement to measure against. It has the longest track record of use in dentistry.

In recent years, newer adhesive cements on a different chemical basis have been added (e.g. glass ionomer cement), but they have not displaced the classic phosphate cement, which continues to hold its own in the dental market with its simple and safe processing and good price-performance ratio. Zinc phosphate cement has only a low flexural strength and it does not stick to the dentin (it is a cement and not an adhesive).

Zinc phosphate cement has high compressive strength, low film thickness, minimal setting shrinkage and thermal expansion and is biocompatible. Compared to other luting materials such as glass ionomer cement or composites, zinc phosphate cement is less sensitive to moisture. The excess produced during the cementation of dental restorations can be easily removed.

Zinc phosphate cement has a high adhesive capacity to the tooth, metal, or even zirconium oxide.

Despite its strong acidity, zinc phosphate cement does not damage the pulp (or the tooth nerve) during the setting phase. It is therefore used as liner to protect the pulp under composite fillings.

Well-known dental brands in Germany and the world for zinc phosphate cement are Harvard cement and Hoffmann's cement. Otto Hoffmann invented this cement in 1892 and had it patented. Until the beginning of the First World War, he had a worldwide monopoly position with his cement.

References

  1. Kalendov´a, A.; Kalenda, P.; Vesel´y, D. (2006). "Comparison of the efficiency of inorganic nonmetal pigments with zinc powder in anticorrosion paints". Progress in Organic Coatings. 57. Elsevier: 1–10. doi:10.1016/j.porgcoat.2006.05.015.
  2. Etzrodt, G. (2012). "Pigments, Inorganic 5. Anticorrosive Pigments". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.n20_n04. ISBN 978-3527306732.
  3. Menke, Joseph T. "Zinc Phosphate Coatings on NonFerrous Substrates -- Part I". PFOnline. Retrieved 2006-08-07.
  4. Raab D: Befestigung von Zirkonoxidkeramiken. DENTALZEIZUNG 2007: 6; 32-34. http://www.zwp-online.info/archiv/pub/pim/dz/2007/dz0607/dz607_032_034_hoffmann.pdf
  5. Raab D: Befestigung von Vollkeramiken aus Zirkonoxid. ZAHNARZT WIRTSCHAFT PRAXIS 2007: 12; 98-101. http://www.zwp-online.info/archiv/pub/gim/zwp/2007/zwp1207/zwp1207_098_101_hoffmann.pdf
  6. Raab D: Fixation of all ceramic restorations – the advantages of cementation. DENTAL INC 2008: March / April 50-53.
  7. Raab D: Befestigung von Zirkonoxidkeramiken. ZAHN PRAX 2008: 11; 16-19.
  8. Raab D: Fixation of full ceramic restorations – the advantages of cementation. 全瓷修复的粘接 — 水门汀的优势. DENTAL INC Chinese Edition 2008: Sonderdruck.
  9. Raab D: Konventionelle Befestigung von Vollkeramikrestaurationen. ZAHN PRAX 2009: 12; 84-86.

External links

Zinc compounds
Zinc(I)
Organozinc(I) compounds
Zinc(II)
Organozinc(II) compounds
  • Zn(CH3)2
  • Zn(C2H5)2
  • Zn(CH3COO)2
  • Zn(CH(CH3)2)2
  • Zn(C(CH3)3)2
  • Zn(C6H5)2
  • Zn(C3H5O3)2
  • ZnICH2I
    • Phosphates
    H3PO4

    		 He
    Li3PO4 Be BPO4
    +BO3     		C (NH4)3PO4
    (NH4)2HPO4
    NH4H2PO4
    -N     		O +F Ne
    Na3PO4
    Na2HPO4
    NaH2PO4     		Mg3(PO4)2 AlPO4 Si P +SO4
    -S     		Cl Ar
    K3PO4
    K2HPO4
    KH2PO4     		Ca3(PO4)2 ScPO4 Ti VPO4 CrPO4 Mn3(PO4)2
    MnPO4     		Fe3(PO4)2
    FePO4     		Co3(PO4)2 Ni3(PO4)2 Cu3(PO4)2 Zn3(PO4)2 GaPO4 Ge As -Se Br Kr
    Rb3PO4 Sr3(PO4)2 YPO4 Zr3(PO4)4 Nb Mo Tc Ru Rh Pd Ag3PO4 Cd3(PO4)2 InPO4 Sn SbPO4
    -SbO4     		Te I Xe
    Cs3PO4 Ba3(PO4)2 * LuPO4 Hf Ta W Re Os Ir Pt AuPO4 Hg Tl3PO4 Pb3(PO4)2 BiPO4 Po At Rn
    Fr Ra ** Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
     
    * LaPO4 CePO4 PrPO4 NdPO4 PmPO4 SmPO4 EuPO4 GdPO4 TbPO4 DyPO4 HoPO4 ErPO4 TmPO4 YbPO4
    ** AcPO4 Th3(PO4)4 Pa U(PO4)2 Np PuPO4 AmPO4 CmPO4 Bk Cf Es Fm Md No


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