Internal Oxidation of Cu-1%Al Alloy

This project came from work that prof. Houbaert had been doing for Pepsi in Mexico before he joined prof. Dilewijns’ laboratory as the professor for physical metallurgy. This involved improving the wear resistance of copper mounds used for the production of glass cola bottles.

The idea was that you enriched a copper melt with a touch of aluminium to the tune of 1%. After you cast the alloy into the correct shape (in our case that was a mere solid cylinder) you then exposed it to an oxidising atmosphere which converts the aluminium (but not the copper) to its oxide and thereby makes the surface layer of the copper shape more wear resistance.

I was tasked with getting all the equipment together, consisting of two tubes inside their respective furnaces, the first one containing Cu2O which at the correct temperature dissociates to CuO and releases oxygen gas into the argon-nitrogen carrier gas. The second furnace contains the Cu-1%Al sample to be oxidised, and the combination of the oxygen content of the carrier gas and the temperature of the second furnace ensures that the aluminium oxidises but not the copper.

I then ran several trials, first of all to see whether the concept worked as intended (it did), and secondly to see what the effect on the properties would be. This involved hardness profiles, metallography and SEM analysis, and in my opinion I had covered sufficient ground in preparation of a thesis student to have a running start in the coming academic year.

The only thing that went somewhat awry was when we were trying to remelt the alloy, hoping to economise on raw materials, and during the remelt process smoke started to appear from the back of the furnace. We quickly tipped out the contents of the furnace, and discovered that the aluminium in the copper had started to eat away at the basic lining -we were just in time to avoid the melt from spilling on the shop floor.

Unfortunately prof. Houbaert hadn’t realised that by the time the thesis student would start on this project, I would be in the army, meaning that the student didn’t have the guidance of the person who had done all the advance work. At the end of all this I received a copy of the student’s thesis and was disappointed that it hardly covered any ground that I hadn’t already done in my preparatory work.

Apart from that this could have been a job that I could have been proud of. As it is it felt a bit like an opportunity missed. When I rejoined the laboratory in 1983, there was no sign of this project, and I can only assume that it had been quietly dropped in the meantime.

Internal oxidation set-up


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