Since the wear scar dimensions are very small, it is hard to find the wear volume by weight loss method.
Mesure surface (roughness) profiles in several locations & directions including a reference (not worn place). From these measurements estimate a volume loss per cycle.
Not easy to achieve. There is a body of literature already.
Dear Ajaz, there is a way of estimating wear loss using statistical parameters and is based on the bearing area curve (Abbot curve). Basically as asperities burnished due to the sliding process, surface roughness is no longer a Gaussian distribution. Find attached a paper that it can be helpful and can provide some illustration on how to measure wear when there is no significant material loss, so if you have a contact or an optical profilometer you can measure these wear parameters (the ones listed in the attached papers). Best wishes :)
As you mentioned before, since the mass loss is very small it is possible that you won´t find any difference when you compare the profilometry measurements from outside to inside the wear tracks, in other words the wear volume would be small as well. Based on my experience I recommend that you perform some area scans and use the equations to perform statistical measurements. Best wishes
Using laser profilometry, one can generate 3D profile of the wear scar. The 3D profile is generated by a laser traversing in linear fashion (2D scans) with consecutive distance (step or resolution) between them customized by user. Area extended in each 2D scan can also be calculated. The final solution of integrating these individual areas into total wear volume is then based on numerical analysis techniques for e.g. Simpson's 3/8th rule, trapezoidal rule etc. Thanks.
Drar Ajaz you csn use an electric balance of 4 digits at least to measure the weight losses in milligrams .