The application of abradable materials (coatings) for gas path sealing in turbine engine can increase its power output, efficiency and reliability. Therefore, the study on their abradability should be a key problem in developing the advanced turbine engines. The abradability of seal materials (coatings) is quite different from wear resistance of common alloys, ceramics and polymers, because they could not be permitted to injure the blade tip during rubbing apart from their enough hardness or strength for prevention from abrasion and erosion. The evaluation of trustworthy abradability and suggestion of feasible criterion as well as modelling could be conducted only in a friction and wear testing rig at elevated temperature and high sliding velocity, which has an environment almost same with gas path seal in turbine engine.
Due to lack of domestic instrument device for estimating abradability of gas path sealing materials (coatings), in this dissertation the establishment of a rubbing test rig which could approximately simulate the operating mode of aeroturbine engine has been described and the measurable parameters and functions of this rig should satisfy the aim for evaluating their friction and wear behaviors at elevated temperature and high sliding speed.
The designs of high rotating mode, rapid heating by radiation image technique, precision incursion rate of specimen controlled by digital system and datum collection system with high frequency response in computer have been firstly adopted in this rig establishment.
On the basis of synthetic regulation of this rubbing rig, the operating variables and tribological behavior (abradability) of materials (coatings) for gas path sealing have been preliminary determined; the operating norm and testing procedure at elevated temperature and high sliding speed have been prepared.
In addition, the tribological behaviors of Ni-Cr-W-BN (abradable layer for gas path seal prepared by two different treatment ) / ЭП 609 have been determined by three device, i.e. pin-on-disc wear tester, single pendulum grooving apparatus and high sliding speed rubbing rig. The results indicate that wear resistances of these rubbing pairs show the same ranking but their frictional coefficients exhibit small difference with increasing of sliding speed. The high velocity of rubbing gives minimal frictional coefficient. The morphologies of worn tracks show the same tendency which agrees with ranking of wear resistances. It means that high speed rubbing test has the superiority in evaluating the abradability of materials (coatings), because the wear volume losses of rubbing pairs, energy consumption during rubbing and densification factor related to abradability could be obtained.
This rubbing test rig at elevated temperature and high sliding speed can be used to develope new kind of wear resistant materials for other industrial practice.
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