Zinc phosphate is an
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
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
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current. The part to be ...
process or applied as a
primer
Primer may refer to:
Arts, entertainment, and media Films
* ''Primer'' (film), a 2004 feature film written and directed by Shane Carruth
* ''Primer'' (video), a documentary about the funk band Living Colour
Literature
* Primer (textbook), a t ...
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
Tarbuttite is a rare phosphate mineral with formula Zn2(PO4)(OH). It was discovered in 1907 in what is now Zambia and named for Percy Tarbutt.
Description and habit
Tarbuttite is white, yellow, red, green, brown, or colorless; in transmitted ...
, Zn
2(PO
4)(OH). Both are known from oxidation zones of Zn ore beds and were formed through oxidation of
sphalerite
Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in Sedimentary exhalative deposits, sedimen ...
by the presence of phosphate-rich solutions. The anhydrous form has not yet been found naturally.
Dentistry
Zinc phosphate
dental cement is one of the oldest and widely used
dental cements. It is commonly used for
luting permanent metal and
zirconium dioxide[Raab D: Konventionelle Befestigung von Vollkeramikrestaurationen. ZAHN PRAX 2009: 12; 84-86.] 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 and
magnesium oxide 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. It is still commonly used; however, resin-modified
glass ionomer cements are more convenient and stronger when used in a dental setting.
References
External links
Phosphates
phosphate
Inorganic pigments
Corrosion inhibitors
Dental materials
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