Improving the surface characteristics of Ti-6Al-4V and Timetal 834 using PIRAC nitriding treatments

SURFACE & COATINGS TECHNOLOGY

卷:339

Article

Attard, B.¹  Leyland, A.²  Matthews, A.³  Gutmanas, E. Y.⁴  Gotman, I.⁴  Cassar, G.¹ 

[1] Univ Malta, Dept Met & Mat Engn, MSD-2080 Msida, Malta

[2] Univ Sheffield, Dept Mat Sci & Engn, Sir Robert Hadfield Bldg,Mappin St, Sheffield S1 3JD, S Yorkshire, England

[3] Univ Manchester, ICAM, Sch Mat, Pariser Bldg, Manchester M13BB, Lancs, England

[4] Technion Israel Inst Technol, Dept Mat Sci & Engn, IL-32000 Haifa, Israel

关键词: PIRAC;    Ti-6Al-4V;    Timetal834;    Nitriding;    Diffusion;    Tribology;   

DOI  :  10.1016/j.surfcoat.2018.01.051

来源: Elsevier

【 摘 要 】

Despite the popularity of a number of techniques of thermochemical diffusion for titanium, in many cases the surface engineering processes used may not be economically viable options for industry. This work focuses on the application of Powder Immersion Reaction Assisted Coating (PIRAC), a relatively inexpensive nitriding treatment that can provide a remarkable improvement in the surface characteristics of titanium alloys. The aim of this work was to determine whether PIRAC could be successfully applied to Ti-6Al-4V and the high-performance near-alpha titanium alloy Timetal 834. In order to study the response of these materials to PIRAC nitriding, techniques such as X-ray diffraction, micro-indentation hardness, surface profilometry, optical and electron microscopy, nano-scratch adhesion testing and ball-on-plate reciprocating-sliding wear testing were employed. These techniques highlighted the markedly different response between the two alloys to the PIRAC treatment; namely, that Ti-6Al-4V forms a thick compound layer, while at the same processing temperature and time Timetal834 does not form any appreciable Ti2N phase instead forming a nitrogen-diffusion case with a thin TiN compound layer at the surface. This inherent difference in nitridability influences the metallurgical response of each alloy. Despite this, the surfaces of both alloys were still hardened considerably and their tribological performance in dry sliding conditions improved compared to the untreated alloys.

【 授权许可】

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