Ball-on-disk

Dekempeneer et al. [96] studied the wear behavior of a-C(N) H films deposited by RFPECVD in CH4-N2 atmospheres, with up to 13-at.% N. The wear tests were done in a ball-on-disk tribometer, under air, at fixed 50% relative humidity. The initial friction coefficient was about 0.2 for all samples, and the wear life of the... 

Figure 1 shows photos of the two benchtop systems that were used in these tests they consisted of a vacuum tribometer for low-speed ball-on-disk sliding in air and pure subambient H3, and an ambient-pressure tribometer using a thrust washer sliding configuration in different atmospheres, including a N/H mixture. 

Recently, ultrathin organic thin films attract attention as new film lubricant [51]. Organosilane monolayer, which is one of the ultrathin films, has been identified as promising boundary lubricants. This is because organosilane molecules interact strongly with substrates and they are robust against solvent and temperature increase. Friction and wear tests of monolayers were carried out with a conventional ball-on-disk type friction tester (SHINTO Scientific Co. Ltd.) in air and tetradecane at 298 K. A 5.0 mm radius ball made of stainless steel was slid on a disk. The friction coefficient was determined by the distortion of a... 

Extensive study has been carried out on the tribological properties of DLC. Different types of tribo-testers such as ball-on-disk and pin-on-disk have been used at low sliding speed or reciprocating conditions to find the friction coefficient as well as the wear rate of the coating. 

Fig. 17 Optical micrographs of Ball-on-Disk wear tested (a) uncoated float glass and (b) 30 nm DLC coated float glass.

Figure 7. Adhesive wear measured in a ball on disk arrangement (a) MeC H and TiN coated discs and a disc of ball bearing steel 100Cr6 and (b) wear of the counterpart (100Cr6 ball). Measurements were performed under ambient conditions.

Stainless steel (100CR6-German) + Stainless steel (100CR6 -German) 0.6 (a) 0.26 (b) 0.106 (c) 0.1 (d) Ball-on-disk vibrotribometer (Optimol SRV - German) 10 mm diameter ball Oscillation = 10 Hz 1.65 mm amplitude Load = 50 300 N Lub (a) none (b) human synovial fluid (c) yellow bone marrow (d) red bone marrow 37 °C Gavrjushenko (1993)... 

Pins and disks for the milestone "Feasibility study of measuring friction coefficient and contact stress damage using conventional pin-on-disk or ball-on-disk... 

CETR 2 tribometer (Center for Tribology, Inc., Campbell, CA, USA) was used to run the tests using a ball-on-disk geometry. This tribometer allows the independent programming of normal load, velocity, radius and duration. Prior to the actual tests, running-rn of the ball was performed at 5 N load with a speed of 31.4 mm/ min for 2h, outside the region to be used for XPS analysis and in the presence of the test lubricant. The running-in was performed in order to create a at spot on the bottom of the ball. This at spot was then placed in contact with the surfaee for the subsequent runs and de ned the apparent eontaet area. 

In the ball-on-disk experiments, a 1 wt.% solution of di-isopropyl zinc dithiophosphate (i-ZnDTP) in decane was used as a lubricant. To dissolve the additive in the lubricant, the solution was stirred at 60 °C for 30 min. 

Ball-on-disk measurements were carried out with a CETR UMT-2 (CETR, Campbell, CA, USA) tribometer, which allows the programming of load, rotational velocity and duration of the tribotest. The tribometer is equipped with a load cell with a maximum capacity of 5N and a resolution of 5 mN in two axes (normal load and fiiction force). Normal load is applied via a spring, and is constantly monitored and adjusted via a feedback loop. The spring constant was determined to be 2.7N/mm in the r-direction and 5.7N/mm in the y direction (fiiction force). Normal load, fiietion foree. 

Fig. 2. Concentric 250 ji,m wide test regions with different loads in the ball-on-disk test.

Fig, 4, (a) XPS elemental maps obtained from a tiibosti-essed sample (ball-on-disk, 25 °C, load ION) worn and non-contact areas are clearly distinguished, (b) 01s spectra extracted from die contact ea (red) and non-contact area (blue) of the 01s map. The 01s chemical state reconstructed maps are shown. 

A commercial microtribometer (UMT-2, Universal Microtribometer, Centre for Tribology, California) was nsed for friction and wear tests using a ball-on-disk configuration. 

Measurement of Boundary Friction on a Ball-on-Disk Tribometer... 

A typical data set from a test using a ball-on-disk tribometer is given in fig. 13.4. The data in hg. 13.4 are for a formulation with 0.003M soybean oil in hexadecane. As can be seen in hg. 13.4, the COF gradually increases with time until it reaches a plateau value, beyond which it remains constant for the duration of the test. The COF for the test is obtained by averaging the values in the steady-state region. The COF for the lubricant is obtained by averaging the COFs of the two consecutive tests. 

The effect of vegetable oil concentration on the COF measured on the ball-on-disk tribometer is illustrated in hg. 13.5. The data in hg. 13.5 are for formulations comprising various concentrations of canola oil in hexadecane. The data in hg. 13.5 show a number of interesting features that are worth pointing out. First, the COF is very high in the absence of the vegetable oil, i.e., for pure hexadecane. COF of up to 0.5 has been measured for pure hexadecane (not shown in hg. 13.5) [18]. Second,... 

FIG U RE 13.4 Typical time vs. friction data from a ball-on-disk tribometer for 0.003M soybean oil in hexadecane. 

FIGURE 13.5 Effect of canola oil concentration on COF as measured with a ball-on-disk tribometer. 

Methyl oleate steel-steel ball-on-disk -2.91 -1.02... 

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. 

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