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</td></tr></table>Adminhttps://catalog.jinharsh.co.in/index.php?title=White_metal&diff=5041&oldid=prevsetup>Revirvlkodlaku: /* White metal */2021-03-07T07:05:04Z<p><span dir="auto"><span class="autocomment">White metal</span></span></p>
<p><b>New page</b></p><div>{{short description|type of decorative bright metal alloy}}<br />
{{about|metallic alloys|the musical genre|Christian metal}}<br />
{{Refimprove|date=February 2018}}<br />
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The '''white metals''' are a series of often decorative bright metal [[alloy]]s used as a base for plated [[silver (household)|silverware]], ornaments or novelties, as well as any of several [[lead]]-based or [[tin]]-based alloys used for things like [[Bearing (mechanical)|bearing]]s, [[jewellery]], [[Miniature figure (gaming)|miniature figure]]s, [[fusible plug]]s, some [[medal]]s and metal [[typesetting|type]]. The term is also used in the antiques trade for an item suspected of being silver, but not [[hallmarked]].<br />
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A white metal alloy may include [[antimony]], [[tin]], [[lead]], [[cadmium]], [[bismuth]], and [[zinc]] (some of which are quite toxic). Not all of these [[metal]]s are found in all white metal alloys. Metals are mixed to achieve a desired goal or need. As an example, a base metal for jewellery needs to be [[casting (metalworking)|castable]], [[polishing|polishable]], have good flow characteristics, have the ability to cast fine detail without an excessive amount of [[porosity]] and cast at between {{convert|230 and 300|°C|°F|0|lk=on}}.<br />
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==Silver==<br />
In compliance with British law, the British fine art trade uses the term "white metal" in auction catalogues to describe foreign silver items which do not carry [[Assay office#UK assay offices|British Assay Office]] marks, but which are nonetheless understood to be silver and are priced accordingly.<br />
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==Tin-lead and tin-copper alloys==<br />
Tin-lead and tin-[[copper]] alloys such as [[Babbitt metal]]<ref>{{US patent reference |number=1252 |issue-date=17 Jul 1839 |inventor=Isaac Babbitt |title=Mode of making boxes for axles and gudgeons}}.</ref> have a low melting point, which is ideal for use as [[solder]], but these alloys also have ideal characteristics for [[plain bearing]]s. Most importantly for bearings, the material should be hard and wear-resistant and have a low coefficient of friction. It must also be shock-resistant, tough and sufficiently ductile to allow for slight misalignment prior to running-in.<br />
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Pure metals are soft, tough and ductile with a high coefficient of friction. [[Intermetallic]] compounds are hard and wear-resistant but brittle. By themselves, these do not make ideal bearing materials.<br />
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Alloys consist of small particles of a hard compound embedded in the tough, ductile background of a solid solution. In service the latter can wear away slightly, leaving the hard compound to carry the load. This wear also provides channels to allow in [[lubricant]] ([[oil]]s). All bearing metals contain [[antimony]] (Sb), which forms hard cubic crystals.<br />
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{| class="wikitable" style="text-align:center"<br />
|-<br />
! % [[Tin|Sn]]<br />
! % [[Antimony|Sb]]<br />
! % [[Copper|Cu]]<br />
! % [[Lead|Pb]]<br />
! Applications<br />
|-<br />
| 93 || 3.5 || 3.5 || – ||style="text-align:left"| Light and medium internal combustion engine big-end bearings<br />
|-<br />
| 86 || 10.5 || 3.5 || – ||style="text-align:left"| Light and medium internal combustion engine main bearings<br />
|-<br />
| 80 || 11 || 3.0 || 6 ||style="text-align:left"| General-purpose heavy bearings (lead increases plasticity)<br />
|-<br />
| 60 || 10 || 28.5 || 1.5 ||style="text-align:left"| Heavy-duty marine engine bearings, electrical machines<br />
|-<br />
| 40 || 10 || 1.5 || 48.5 ||style="text-align:left"| Low-cost, general-purpose, medium-duty bearings<br />
|-<br />
|}<br />
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==See also==<br />
{{div col|colwidth=23em}}<br />
* [[Britannia metal]]<br />
* [[Nickel silver]]<br />
* [[Pewter]]<br />
* [[Plain bearing]]<br />
* [[Pot metal]]<br />
* [[Punchcutting]]<br />
* [[Spelter]]<br />
* [[Wood's metal]]<br />
* [[Zamak]]<br />
{{div col end}}<br />
<br />
==References==<br />
{{Reflist}}<br />
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{{Authority control}}<br />
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{{DEFAULTSORT:White Metal}}<br />
[[Category:Alloys]]<br />
[[Category:Bearings (mechanical)]]</div>setup>Revirvlkodlaku