Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.655503
Title: Tribo-corrosion maps for steels, titanium and titanium carbide materials
Author: Rasool, Ghulam
ISNI:       0000 0004 5365 2547
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2015
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Abstract:
In this project, research work was carried out on the tribo-corrosion behaviour of titanium carbide composite coatings produced by Tungsten Inert Gas (TIG) welding torch melting process on steel and titanium substrates. The integrity of TiC composite coatings were checked and analysed on the substrates. The effects of change in sliding speeds and normal loads on wear behaviours were investigated for dry sliding conditions and tribo-corrosion maps were constructed with a tribo-system approach. The work was carried out in the following phases: In phase I, a fundamental study of the wear behaviour of two steels of different Cr contents and hardness were carried out. Pin-on-disk apparatus was used for testing 303stainless steel (303SS) disks and 8620 low alloy steel pins. For 303SS adhesive wear and tribo-oxidation were predominated at relatively low sliding speeds and adhesive wear was predominated at high sliding speeds and normal loads. In contrast, oxidative wear was more prevalent for the low alloy steel. Wear mapping approaches were undertaken to represent the transitions in wear modes and wear mechanisms as a function of sliding speeds and applied loads. The different wear maps generated for the pins and disks were discussed in the context of the wear mechanisms observed in the tribological contact. In phase II, dry sliding wear tests were carried out on 303SS disks (uncoated and coated with TiC composite coatings) against alumina balls as a counterface on pin-on-disk configuration. The composite coatings increased the surface hardness hence the sliding wear resistance of the 303SS substrate. Wear maps for both uncoated and coated materials were developed on the basis of tests results. These maps show that the mild wear regime for the composite coating was expanded to a higher range of sliding speeds and normal loads. For the composite coating, an additional wear mode transition i.e. from the mild to very mild regime occurred at low sliding speeds and normal loads. In phase III, experimental work was carried out on a pin-on-disk sliding wear testing rig on hardened steel (A.I.S.I. 0-1-Ground Flat Stock) disks and titanium (Ti) uncoated and coated pins with titanium carbide (TiC) composite coatings. For uncoated Ti and hardened steel tribo-couple, pins' material was transferred to disks and covered the wear tracks almost for each combination of sliding speed and normal load. High wear of Ti was found against hardened steel. Adhesive wear was prevalent for Ti pins along with abrasive, plastic deformation and delamination against hardened steel disks. While for the Ti base TiC composite coatings against hardened steel different wear behaviour observed. The composite coating increased the surface hardness hence the sliding wear resistance of the Ti substrate. Dry sliding wear behaviour of hardened steel disks was characterized by abrasive-oxidative wear at lower normal load while adhesive-oxidative wear was predominated at high normal load with iron oxide transfer to the coated pins for the range of sliding speed. In contrast, micro-abrasion and oxidative wear were predominated for the TiC composite coatings pins along with very mild adhesive-abrasive wear. A tribo-system approach was adopted to investigate the wear behaviour of TiC coatings and hardened steel against each other. Wear maps for both uncoated and coated materials were constructed on the basis of tests results. The tribo-corrosion maps show that due to TiC composite coating wear resistance of the substrate was increased. Higher tribo-corrosion resistance of the TiC composite coatings was found on Ti substrate than that of 303SS substrate. Moreover, the surfaces treated with TiC coatings by TIG welding torch as heat source, expanded the mild wear regime to a higher range of sliding speeds and normal loads with creation of a new wear regime i.e. very mild wear and elimination of severe wear regime.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.655503  DOI: Not available
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