AGMA 90FTM10-1990 pdf download.The Mechanism of Failure With and Without Titatanium Nitride Coating in Roller Tests.
The coefficient of friction varied with the difference in the base material and coating on the roller For an the roller pairs it appeared that the surface was uniformly torn out due to frictional forces and wear however, the contacting surfaces became smoother as shown in Table 3
3.12. Unlubrlcat.d tests
As the failure resistance of the coated and uncoated rollers could not be estimated from the test results obtained under lubrication, the failure test was carried out unlubricated The testing was stopped when, failure was observed. The initial friction coefficients were about 0 12 to 016 respectively The relationship between the coefficient of friction and the wear length is shown in Figure 4.
Figure 5 shows the running time until failure occurred. The test was carried out twice for each roller pair, and the m.an value out of two measured values is shown The life of the coatings of the roller pairs Type B and D was longer than that of roller pairs Type A and C.
4 OBSERVATION OF FAILED AREAS
4.1. Lubricated tests
Figures 6 AB show a micrograph of the wear track of the rollers Type A and C after a 1.2 10+6m Figure 5 Tm. to failure of unlubricated roller ;airs
wear length Th, surface layer of the roller Type C was slightly more sheared in the direction of frictional force Along the contact surface and in the vicinity of the surface there are distinct modifications of microstructure induced by shear stresses and temperature This can be confirmed by the fact that the hardness is considerably wqh.r than that in the subsurfaces Figure 6 B shows the change in Vickers microhardness with depths measured along th. line A – A. probably caused by work-hardening due to the action of compressive Stress frictional force and coohng with lubricating oil Figure 7A shows a micrograph of the wear track of the roller Type B after lailure at about 1 2 10- m An undulation was observed In the circumferential direction of th. roller and the TiN surface layer was fatigue—damaged in th. direction of th. frictional force Figure 78 shows a micrograph of the section plane cut in aiual direction of the roller and the distribution of Vickers microhardness measured along the line A-A From this micrograph it can be seen that the metal in the vicinity below the TiN layer was distinctly deformed Th. hardness in the vicinity of the boundary of the TiN layer was the same as that before the tests The TiN layer had a larger elasticity modulus than the base material, and that the compressive, shear and thermal stresses cause a much larger deformation in the base material in tha vicinty of the TiN layer than that in the TiN layer On the other hand th. surfac, temperature was lower then that used for heat treatment.AGMA 90FTM10 pdf download.