Four-ball tester

Not only can molecular design improve the miscibility with other oils, it can also confer ILs with special functions, such as antioxidation and the ability to adapt to a broader temperature range. We synthesized three imidazolium-based ILs containing sterically hindered phenol groups with antioxidant functions and evaluated the tribological behaviors of these ILs as additives for PEG appfication in steeFsteel contacts on an Optimol SRV-IV oscillating reciprocating friction and wear tester, as well as on MRS-IJ four-ball testers [100]. The rotary bomb oxidation test (RBOT) test, thermal analysis, and Cu strip test results revealed that synthesized ILs possessed excellent antioxidation capability. 

Tribological investigations were carried out by means of a four-ball tester and a T-11 tester with a ball-on-disk friction pair. Antiseizure properties (scuffing load— A. seizure load—and limiting pressure of seizure—as well as motion resistance and wear at a constant load were determined using a four-ball tester. It has been found that ethoxylates used as additives significantly modify tribological properties. The measured A. Az> Poz values increase by as much as several times compared with water. The coefficient of friction and wear measured at a constant load decrease considerably to about half relative to water. 

The coefficient 222.47 is imposed by forces acting in the four-ball tester. 

FIGURE 18.20 Friction coefficient changes vs. time for water and 1% aqueous solutions of SML/ESMIS mixtures at a load of 3000 N (four-ball tester). (Note Test for water at 2000 N.)... 

FIGURE 18.21 Effect of SML/ESMIS mixture ratio on mean friction coefficient value (1% solutions) using a four-ball tester at a friction-pair load of 3000 N. The following SML/ ESMIS ratios were investigated 0 10, 1 9, 3 7, 5 5, and 7 3. 

Lubricating performance of oils with or without additive is usually evaluated by running tribological tests on a four-ball tester. The tester consists of a steel ball rotating under load on a set of three similar stationary balls. The speed, load and temperature during the test are precisely controlled. After the wear test, round wear scars are formed on the lower three balls and their diameters are measured using a microscope. The diameter of the wear scar (WSD) in millimetres or the area of the wear scar (AWS) is a measure of the AW characteristics of the lubricants. In this case the tests were preformed under conditions of 400 N, 1450 rpm and 30 min. 

Soft metals such as indium, tin and bismuth are good solid lubricants, but they cannot be used as a lubricating oil additive because of their poor dispersibility in oils. However, their nanoparticles prepared by the direct solution-dispersing method have been found to have better oil solubility and can be directly used as lubricating additives. Their tribological properties have been evaluated on a four-ball tester and the results are presented as follows. 

This remarkable ability to lubricate deformation of steel can be readily demonstrated in the laboratory with the two common test machines, the Shell Four-Ball Machine and the Falex Pin and V-Block Tester. As described previously in Chapter 5, lubricants with more than about 35% of molybdenum disulphide will result in extrusion of steel test pieces at temperatures little higher than room temperature. In both cases the surface area of the specimens is increased by about 200% at low power smoothly and without pick-up on the counterfaces. 

The antiwear behavior of P-lactam cephalosporin antibiotics such as cefixime, cefadroxil, and cephalexin has been studied using the Four Ball lubricant tester in paraffin oil (14MI30500). A novel electrochemical sensor... 

The strength is commonly measured in a four-point bending mode or a ring-on-ring method using a mechanical tester on suitably sized test coupons with or without surface abrasion. (It is strongly recommended that edge-independent techniques be employed.) Steel ball drop tests for ophthalmic lenses and bird impact tests for aircraft windshields are also carried out. 

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