Hi Wasif
Hardness testing is important and normally a required test for abradable (clearance control) coatings. Mostly the Rockwell superficial hardness test is employed using the HR15Y scale. The HR15Y hardness scale requires 1/2" diameter steel ball indenter with a total load of 15kg.
Try searching this forum and the old message board with "HR15Y" or "abradable". Try this link for more info on
Rockwell Superficial Hardness Testing
The Google search on 'www.gordonengland.co.uk' (near bottom of page) works quite well as an alternative search method. Advantage being that its quick and searches all of the site, disadvantage being it will only show up google indexed pages.