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Babbit, solder, tin
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Babbit is an alloy with antifriction properties. Produced from lead or tin, used to create lubricating layers sprayed between moving parts or filled between bearing shells.
| Physical properties of Sn | |
|---|---|
| Atomic (molar) mass g / mol | 118,71 |
| Atomic number | 50 |
| Density [g / cm 3 ] | 7.31 |
| Melting point t ° C | 231.9 ° C |
| Degree of oxidation | 4, 2 |
| Thermal conductivity K [W / (m · K)] | 16.3 |
| Molar volume cm 3 / mol | 66.8 |
general characteristics
The most common alloys are made of such compositions: 10% Cu and 90% Sn, 89% Sn, 4% copper, 7% antimony, etc. Their melting point is in the range 300−400 ° C. There are various variants of tin-based babbits: B83, B83C, B88, SAE11, SAE12, ASTM2, which have different properties. For example, increased viscosity of the material or a different coefficient of friction. If we compare lead alloys with tin, the former have higher properties of resistance to corrosion, to wear and to conductivity of heat, but its price is higher.
Babbits based on lead
B16, БН, БКА, БК2, БК2Ш, БСб, SAE13, ASTM7, SAE15, SAE14, ASTM15 are capable of transferring higher temperatures than tin ones. They are used most often for the production of rolling mill bearings and diesel engines.
| Physical properties of Pb | |
|---|---|
| Atomic (molar) mass g / mol | 207.2 |
| Atomic number | 82 |
| Density [g / cm 3 ] | 11.34 |
| Melting point t ° C | 327.5 ° C |
| Degree of oxidation | 4, 2, 0 |
| Thermal conductivity K [W / (m · K)] | 35.3 |
| Molar volume cm 3 / mol | 18.3 |
disadvantages
A significant disadvantage is a high propensity to fatigue. This in the future greatly degrades the quality of the bearing. Due to its low strength, babbit is only used in bearings that have a strong, steel or cast iron body. The time of accident-free operation of bearings usually depends on the thickness of the babbitt layer, which is poured onto the steel liner. The regularity is the following, the smaller this layer of babbitt, the longer the bearing will last.
Solder
It is an alloy or metal, which is used for soldering and joining various parts. It should have a melting point much lower than the metals that are connected with it. The solder is used to make a sealed and mechanically strong seam. During soldering, the solder usually spreads over all the metal and fills all the gaps and voids between the parts to be joined.
Buy at a bargain price
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