In dry tribotests against stainless steel ball, the coefficient of friction was less than 0.24 as Ti was less than 36 at.%, but abruptly increased to 0.39 as Ti reached 42 at.%. Extremely low coefficient of friction of 0.046 was obtained with oil lubrication.
In 2009, in part because of lobbying by Minnesota Coach John Anderson, the N.C.A.A. adopted the testing standard known as BBCOR, for Ball-Bat Coefficient of Restitution, to replace Ball Exit Speed Ratio, or BESR, starting with the 2011 season.
When sliding against soft copper ball, the friction coefficients of the DLC films were higher and increased with the sliding process from an initial friction coefficient of 0.15 with a promising wear behavior.
First, an experimental analysis is carried out on six different balls, the tennis ball hardness and restitution coefficient are measured and compared.
Further, since the friction coefficient for ball bearings is about 0.001 ~ 0.008, the efficiency of the one-stage gear pair is Gη, and Gη > 98%%.
Conversely, in the case of the alumina ball, the average friction coefficient increased with increasing sliding speed regardless of Si content, indicating that the abrasive wear behavior was more dominant when the coating layers slid against an alumina ball.
In the case of steel ball, the average friction coefficient slightly decreased with increasing the sliding speed regardless of Si content, due to adhesive wear behavior between coating layer and steel ball.
Wear property was determined by ball-on-disc sliding wear test under Al2O3 ball revealed that friction coefficient of coated films was decreased from 0.61 to 0.34 and wear depth was remarkably reduced as one third as that of A6063 since dispersion hardening of those intermetallic phases is beneficial to improvement of wear resistance.
The friction coefficient against ball-bearing steel increases to values of approximately 0.7 0.8 at enhanced temperatures.
