Electronic Thesis and Dissertation Repository


Master of Engineering Science


Mechanical and Materials Engineering


Dr. Robert J. Klassen


Boronizing or boriding is a technique to mitigate wear damage in industrial valves made of age-hardenable Inconel® 718 which is a nickel-based superalloy. Boriding involves immersing the part in a patented boron-based compound and heating over 800 oC.

Boriding combined with aging has a detrimental thermal effect and was the subject of this investigation. The effects on hardness, wear and grain size, of boriding and aging separately, subsequently, and simultaneously, were investigated to observe the microstructure and mechanical properties.

The results show that boriding has negligible effect on the grain size and the hardness of the substrate. Besides, a boride coating can improve the surface hardness by a factor of five and reduce the wear damage by over 75%. As the wear performance strongly depends on the coating thickness, we found that initial aging and subsequent boriding delivers the thickest layer and is the best method for boriding of Inconel® 718.

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