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Master thesis: Corrosion mechanism of lead-free brass alloys

Do you want to work with corrosion and material characterization? Then come and apply for this master thesis!

Thesis subject/Assignment 
Brasses are copper-based alloys with zinc as the major alloying element, which are commonly used in, for example, taps, valves and fittings in contact with drinking water. Traditionally, brasses are alloyed with lead for several reasons, such as lubricant during the cutting operation, helping casting, low price etc. Due to the harmful health and environmental effects, lead should be phased out for use in most products, which also include brass alloys. Consequently, the legislation for lead reduction will become strengthen in the near future. This, in turn, has started an ongoing process to phase out lead in brass products worldwide which also strongly affects the Swedish manufacturers of these products today.

Dezincification is a type of de-alloying, and occurs in brass due to the fact that Zn is less noble than Cu – and therefore more easily corroded. Selective corrosion of Zn results in a brittle and porous structure, which is highly undesirable in drinking water systems. Different alloying elements and the microstructure contributes to the tendency for dezincification of different alloys. Today, all products in contact with drinking water must be dezincification resistant, and as such, be reliably evaluated in this regard. An accelerated test method described in standard SS-EN ISO 6509 is currently used to determine the dezincification resistance of alloys and components. However, this test method was developed for the old leaded brass alloys and it is not established whether this method is suitable for the modern lead-free brass alloys.

Project research topics 
The main purpose of the master thesis work is to evaluate the reliability of current standardized methods for determining dezincification resistance. To this end, more knowledge needs to be acquired regarding the mechanism of dezincification in modern lead-free brass alloys. The conclusions of this work will have an immediate impact on the development of modern evaluation strategies of new brass alloys; Is the current accelerated standard test still reliable or is there a need to develop new adapted testing methods?

Project activities
The master thesis work will be performed as a part of the project “Optibrass”. Optibrass is financed by Vinnova and 12 industry partners.

The work will include an initial literature review of the current knowledge regarding the factors influencing dezincification of lead-free brass alloys including modern testing methods. This part may also involve interviews with leading international researchers. The next step is to setup an experimental plan including both standard testing (SS-EN ISO 6509) and electrochemical testing in tap water and CuCl4 solution. The exposed samples will be characterised at RISE by using different techniques such as electron microscopy and chemical analysis. The results will contribute to development of modern testing techniques for dezincification of lead-free brass alloys.

Student profile
We are looking for a master’s student within the areas of chemistry, material science or similar that is interested in doing the above described project as her/his master’s degree project. The master will involve practical work at RISE corrosion laboratory and labs for material characterization in Kista.

Location and start date
The Corrosion Department of RISE is located at Isafjordsgatan 28A in Kista, Sweden.

Master thesis work start in January 2021.

Welcome with your application!
Interested? Send in your application (CV and motivation letter) no later than October 31th. If you would like to know more, please contact supervisory team at RISE:

Main supervisor: Charlotta Obitz, phone: +46 73 088 76 75

Co-supervisor: Clara Linder, phone: +46 70 562 47 04

 

Master Thesis, RISE, Stockholm, material science, corrosion, chemistry, electrochemistry

About the position

City

Stockholm

Contract type

Temporary position 3-6 months

Job type

Student - Master Thesis/Internship

Contact person

Charlotta Obitz
+46 73 088 76 75

Reference number

2020/231

Last application date

2020-10-31

Submit your application