Abstract
A molybdenum boride (MoB) coating was prepared on molybdenum (Mo) by an in-situ chemical vapor deposition method. To develop a fuller understanding of the effect of depositional conditions on the growth of MoB coating formed on Mo substrate, this paper studied the phase composition and microstructure of the coating at varied conditions. At the same time, the relationships between the growth of the coating in thickness and depositional conditions were also investigated. The phase composition of the coating, which was prepared using 0.2 wt % boron (B), was composed of MoB and Mo2B phases. The single MoB phase was obtained using a high B content (above 0.2 wt %). The microstructure of the coating showed that MoB coating could be prepared at temperatures over 900 °C. With the increase of temperature and time, the thickness of the coating increased. The growth of the coating was also influenced by the content of NaF. With increasing content, the thickness of the coating first increased, and then decreased. In addition, the prepared coating had a high hardness (3130.85 HV), and the mass change of the coated sample was only 4.92 mg/cm2 after isothermal oxidation at 600 °C for 100 h. The MoB coating could provide a good oxidation resistance for Mo at 600 °C.
Highlights
Boriding is a reliable surface hardening process which is widely used in industrial production to form a superhard wear-resistant surface
XRD analysis, analysis, the molybdenum boride (MoB) coating coating was formed on Mo substrate due to B
MoB coating was successfully prepared on Mo by a pack cementation process
Summary
Boriding is a reliable surface hardening process which is widely used in industrial production to form a superhard wear-resistant surface. Metals 2018, x FOR PEER REVIEW the element is8,deposited on the surface of the substrate followed by a solid-state diffusion, of which is considered as the rate-limiting step [4] It is a diffusion coating process, so metallurgical bonding is Gaseous species of the element formed in the pack at high temperature are brought to the formed between the coating and metal substrate. The composition and properties of the coating are substrate surface, and the element is deposited on the surface of the substrate followed by a solidsensitive the process parameters, such pack composition, composition, temperature, stateto diffusion, which is considered as as thethe rate-limiting step [4] It substrate is a diffusion coating process, so and time. There are very few pack of composition 90SiC-5KBF4 -5B4 C (wt %), where the temperature (1000 ◦ C, 1100 ◦ C) and time studies available about boride coatings on Mo prepared by HAPC. The hardness, elastic modulus, and lowtemperature oxidation behavior of MoB coating were studied
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
