With properties historically viewed as being mutually exclusive, SM-100™ is immune to corrosion while maintaining impressive wear and erosion properties, all while being ultra elastic, non-magnetic, and 18% lighter than steel. You can call on it when you’ve run out of options and can’t afford a failure. It is routinely used in situations where there is a combination of corrosion and wear issues. We supply mill shapes as well as finished components.
Coefficient of Friction
|SOT results for various balls running against 440C plates lubricated with Pennzane 2001A oil.|
A high coefficient of friction is detrimental to highly loaded bearing and wear components. Parts prematurely wear out and excess heat is generated. NASA conducted tests comparing SM-100 against the gold standard for bearing components, 440C stainless steel.
The findings clearly show that SM-100 has a lower coefficient of friction – which unto itself is impressive. On top of the lower friction, notice that the SM-100 has twice the life of the 440C.
The left of the plot shows some titanium results, which as expected do not wear well at all, but are of course quite corrosion resistant. So anytime you wish you could combine the corrosion resistance of titanium with superb wear resistance, call on SM-100.
|Compression behavior of hot rolled plus hardened SM-100. Note: The maximum stress level is limited by test fixtures, not the specimen.|
After NASA determined the life expectancy and coefficient of friction for SM-100, attention turned toward other mechanical properties. A common test in the bearing world is the standard compression test in which a cylindrical specimen is subjected to a compressive load until failure – only this time the material didn’t fail.
As you can see in the plot, once the initial load was relieved, the material strained about 1% and then took on a superelastic behavior. This has two major positive design implications:
- If your component experiences an unplanned load shock to the system, SM-100 will only strain 1%, likely saving catastrophic failure.
- More interestingly, however, was NASA’s finding that after the 1% strain introduction, SM-100 becomes superelastic. This means that if you impart the strain in the system prior to service use (and there are numerous ways to do this), you have a component on your hands that can absorb a tremendous amount of stress without failure – something the steel family only wishes it could claim.
Damage Level Threshold
|Graphical depiction of the indentation load tolerance of various bearing material combinations.|
The extremely intelligent folks at NASA Glenn uncovered yet another amazing property for SM-100, namely the Damage Threshold Load Capacity. The basic findings mean that a SM-100 solution won’t corrode or rust, and can absorb an order of magnitude more load before failure over other bearing materials. There is literally no material that comes close to keeping up with SM-100.
These finding have enormous practical implications for bearings that are used in harsh environments where foreign particles such as sand or mud may be introduced into the bearings system. Due to a high Modell Number, SM-100 can absorb the intense loading that is imparted when a foreign particle is in the system, and subsequently discharge the particle with no detrimental effects to the system. So if you’ve ever had a bearing failure because sand or other particles got introduced into your system – give us a call.
NASA best summed up the results of this data by stating “The combination of high hardness, moderate elastic modulus, large recoverable strain, low density, and intrinsic corrosion immunity provide a path to bearings largely impervious to shock load damage.”
Tighter Dimensional Tolerances
Due to the super-fine microstructure of SM-100, extremely tight tolerances can be achieved to get your components to their most efficient grade. The microstructure also means that the components have a higher level of inspectability and better mechanical properties than the competition.
Material Property Comparison Table
|Nominal Comparative Properties for Conventional Bearing Alloys Against SM-100|
|Hardness||56 to 62 RC||58 to 62 RC||1300 to 1500 Hv||60 to 65 RC|
|Thermal conductivity W/m-° K||18||24||33||36|
|Tensile/flexural strength, MPa||*TBD||1900||600 to 1200(bend strength)||2500|
|Young’s modulus, GPa||47-90||200||310||210|
|Fracture toughness||TBD||22 MPa/√m||5 to 7 MPa/√m||20 to 23 MPa/√m|
|Maximum use temperature, ºC||~400||~400||~1100||~400|
|Electrical resistivity||~80X10 6 Ω-cm||~36X10 6 Ω-cm||Insulator||~60X10 6 Ω-cm|
|*TBD means to be determined|