Development of coatings pertinent to the protection of steel pipelines used in the oil and gas industry

Abstract

In this thesis, different types of metal dichalcogenides thin films have been prepared for the application in corrosion resistance of pipeline steel X65. The main objective of this work is to develop thin films for prevention of oil and gas pipeline corrosion. Sulfur scales have been prepared on steel substrates by Aerosol-Assisted Chemical Vapor (AACVD) reaction method in the lab to understand the growth mechanism and characteristics of scales produced on steel. It is found that the troilite phase of iron sulphide is formed by tertiary alkanethiols and primary alkyl disulfides while pyrite phase was produced when tertiary alkyl disulfides were used as precursors. In the next phase of this work, polycrystalline thin films of chromium doped tungsten disulphide were deposited (WS2) onto glass and steel substrates by AACVD using bis(diethyldithiocarbamato)disulfidothioxo tungsten(VI) (WS3L2) and tris(diethyldithiocarbamato) chromium(III) [Cr(S2CNEt2)3] (CrL3) complexes. These coatings can be used as protective layers against corrosion resistance. It is observed that hexagonal tungsten sulfide (WS2) and hexagonal iron sulphide is formed on steel while highly crystalline and monophasic hexagonal WS2 is produced on the glass substrate. The films were characterized by several techniques to study the formation behaviour, structure and chemical composition. In the next work, the surface wettability of iron sulfide thin films produced on X65 steel substrate by AACVD has been tuned by chemical modification with stearic acid. The effect of different modification parameters such as the concentration of stearic acid and modification time is studied in detail and optimum conditions are found to create superhydrophobic surfaces. Finally, a simple method is studied for the large area and cost-effective fabrication of thin films. Binary, ternary (CFS) and quaternary (CZTS) metal sulphide films are deposited onto the glass substrates by air-spray annealing method and characterized by several advanced characterization techniques. The deposited films are highly crystalline and show some unique morphologies. This process is a simple and inexpensive method for large area deposition of binary, ternary and quaternary metal sulphide films with excellent control over film composition.

Date of Award	1 Aug 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	David Collison (Supervisor) & David Lewis (Supervisor)