Tag Archives: Thesis

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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Electro-Slag Refining


During my last three years at university, there was only one other person doing metallurgy in my year, and that was a person called Charles Gheenen. For his thesis he decided to do some work at Professor Dilewijns’ laboratory, which involved working on the new Electro-Slag Refining (ESR) equipment they had acquired in their off-site premises in Zwijnaarde.

I see that Wikipedia calls it “Electro-slag Remelting”, but essentially it involves letting a current go through a molten slag between a bar of steel (the one to be refined) and the baseplate, where the bar of steel gradually melts and deposits itself onto the baseplate, leaving most of its impurities behind in the slag. I seem to remember that it was being used on an industrial scale in Russia, but I’m not aware that it’s much in vogue n the current steel industry, where making clean steel is produced through processes such as vacuum degassing stations.

Anyhow, Charles did a great job on hoovering up most of the literature on the subject, and since throughout his thesis year they had very little luck in producing any electro-refined steel, the literature survey took up the lion’s share of his thesis. Charles was also employed for a while by Prof. Dilewijns’ laboratory as a researcher, starting a little bit earlier than I did, and seeing as he had done the initial work on ESR was the natural person to head the sequel thesis done by a student whose name escapes me now.

This student was now in the unenviable situation that there was very little literature left for him to the first part of his thesis that hadn’t already been covered in the thesis that Charles had written. Although in the end he was more successful in producing actual steel from the equipment, there wasn’t much of it and surely not enough to come to many conclusion of how it affected the steel properties.

On top of that, Charles left his position at the laboratory for Union Minières near Antwerp (I think that’s where his father used to work) after only a few months, and I had to take over as leader for the project. I remember going to Zwijnaarde on a number of occasions, and trying out different configurations to sharpen the tip of the steel bar so that we could get the localised current high enough to start the melting process.

At some point there was also a minor panic when the student mentioned the possibility of noxious gases emanating from the molten slag, so we had to wear gas masks with microphones in them so that we could communicate between some of the workers on the top platform and those observing the process from below. I also remember that the first time we were successful we came back in triumph, declaring “we have a little one !” (referring to the fact that although successful, the resulting refined steel was less than a foot in length).

All in all, the student in question just scraped through for his thesis with 50% of the points, which confirmed in my mind that it’s not a good thing to do a follow-up thesis, since yours will always be compared, and often unfavourably, with that of your predecessor (Charles’ thesis received a rating of 70%).

I’m not sure what happened to the Electro-Slag Refining equipment. At no time in my subsequent time at Prof. Dilewijns’ laboratory did I hear any further mention of it. Had the equipment been on loan, and had been returned from where it came from ? Whatever the case, as I’ve mentioned earlier, I think subsequent developments in the steel industry made ESR a superfluous process, unless you wanted to go for small quantities of steel in a super-refined state.

Salt Spray Test


As I may have mentioned in an earlier blog, the topic of my thesis was the investigation of weak acidic chloride solutions for electrogalvanising a steel substrate, and examining the respective corrosion behaviours of zinc layers produced using different coating parameters. I also used different types of chromate treatments in an attempt to improve their corrosion resistance.

So far so good, but how to evaluate how well the zinc coating was performing ? Obviously there was the possibility of a visual examination, and cross sections could be made to see how the coating thickness varied across the sample. But most important of all was the sample’s corrosion behaviour, and this was evaluated using the laboratory’s salt spray test chamber.

The idea was that different samples with varied coatings and chromate treatments would be hung up in the test chamber until first white rust (i.e. corrosion of the zinc) or red rust (corrosion of the underlying steel substrate) occurred, or until a predetermined maximum time had elapsed. For some of the better chromate-treated samples the test duration could last as long as 320 hours (about 2 weeks).

Obviously, the test had to be interrupted at regular intervals in order to examine the samples, and here I must admit that I had my doubts whether I performed the test properly : you were supposed to wash the samples clean prior to re-inserting them in the chamber. I’m fairly certain I didn’t do this. I also don’t remember whether I discussed the test with my supervisor in order to make sure that I followed a standard way of operating the equipment.

I do remember having a discussion with my predecessor, who had performed similar tests using alkaline solutions, plus I had the benefit of being able to look up stuff in his thesis.

Still, the literature states that the salt spray test should not be used to predict actual corrosion behaviour in a natural environment, but instead compare the efficacy of different samples under controlled conditions. I suppose that’s what I did, and since I used the same methodology throughout, I suppose my data must have had some meaning, if only through its internal consistency, but comparison with other data sets might be more problematical.

To be honest, I never had any feedback from the company who supplied the chemicals for the weakly acidic solution or the chromate treatments, so not really sure how much practical use the outcome of my thesis had.

Researcher


lWhat is it like to be a researcher at a Belgian university ? Not saying that my case was typical for all researchers, chances are that I wasn’t since I was only filling in time, first waiting for my army service to come along, and later whilst trying to find a job.

Especially before the army, when I was living in Ghent “op kot” (i.e. renting a student room near the university), it felt more like being a student with money. So I could buy books and records, and go out for meals and for a drink in the evening, something that my limited budget as a student (B.Fr.500 a week) just wouldn’t allow.

It also meant that this time I had to learn my stuff properly, unlike when as a student you learn mostly to pass the exams, and if you don’t need it afterwards, you tend to forget about it. After all, if you have to give the practical sessions of the syllabus to the students, you better make sure that you know what you’re talking about.

And then there were the things you had to do to keep the money flowing into the laboratory, like in my case performing metallurgical examinations of samples (mostly welded stuff) for Volvo Trucks, who at the time did not have their own metallurgical lab, and relied on us to provide the expertise. At the same time, it sharpened up my report writing skills, since all reports issued by the laboratory had to be vetted by the professor, and I must admit that some of my earlier attempts came back rather bloodied in red ink.

Apart from that, I remember doing literature surveys so that the professor could remain au fait with current developments in steel without having to trawl through all of the literature. One I remember in particular is a study I did on interstitial-free (IF) steels – my initial grab of the literature was a bit confused, and it meant the IF study had a large addendum of other low carbon steels that were under development at the time, such as ultra-low carbon bainitic steels or rephosphorised steels.

I also remember being involved in guiding a student through his thesis work on Electro-Slag Refining, and doing the ground work for a future thesis (but more about that one in a later blog). I also did a literature survey on dual phase steels, which was the starting point for the doctorate’s thesis for one of the other researchers.

So in the end, did I do any ground-shaking work as a researcher ? Probably not. Did it prepare me for my future career as a metallurgist ? Again not sure, although it can’t have hurt. It definitely gave me a head start when I began my job with Iscor, being a notch above some of the engineers-in-training who had just come out of university.

False Starts


This is the story of how three times, twice when I was at university, the other time when I started working life, I had to regroup because the initial attempt failed.

When I started out as a student, I made the mistake of commuting every day between Bruges and Ghent, a half-hour train journey plus additional travel which in all amounted to 2 hours per day lost in travel. I also was caught out by the system of tests taken throughout the year which counted for a third of the points and where my performance varied from bad to abysmal.

The result ? I was advised to stop the first set of exams because I would have failed so badly that I would have been refused a resit. But even with a better effort in September, trying to make up for the lost points of the tests proved insurmountable.

Still, passing with distinction when I redid the first year proved that I had a learnt a number of valuable lessons. The first of these lessons is to develop a method of studying that gets you through tests and exams. The second is to make sure that you make use of whatever resources available to you at the time, which of necessity includes past exam questions. The latter make you realise that there’s only a limited number of questions that can turn up in an exam, and that you can develop a system of keywords that guide you through each topic.

The second time was when I had to select a topic for a thesis, and chose “Electro-galvanising in weak acidic non-cyanide solutions”, a follow-on of a similar thesis done the year before in alkaline solutions. The conclusion : never do a follow-up thesis, because unless your effort is clearly superior to the earlier attempt, you’re going to be compared unfavourably with it. Although a score of 70% on the thesis was OK-ish, a slightly higher score would have landed me a “great distinction” rather than the distinction which marginally missed the higher grade.

The last false start was not to understand the industry I was going to enter, and what steps to take to perform well from the start. For starters, I did not fully understand what an engineer actually did, not realising that the syllabus only spoke of how systems were supposed to work in an ideal set-up rather than show how engineers carry it along to overcome all the bugs and warts that real life throws at the unwary.

I also had not realised that, in order to find a job at any company as a metallurgist, it’s a good thing if your face is already known, which you do by doing some holiday work in companies that you take a fancy to. Since I didn’t know this, I took up the offer of working as a researcher at the university, not realising that in an industrial environment a job at a university is not seen as a “proper job”. That became very clear at the time I had started job hunting on leaving the army. Plus, the last thing I learnt during the 8 months I was unemployed is that it’s far easier to look for a job when you’re still in a job rather than from an unemployed position.

This became abundantly clear when after nearly half a year of unemployment I had an interview, and the interviewer looked at my CV. His remark that I was still unemployed after several months clearly carried overtones of “What’s wrong with you ?”. That’s why, when I had the good fortune of getting a second stint at the same Laboratory for Iron & Steel Making, I immediately made sure that I went on the job hunt. That’s also why, when the professor had the bad news that my annual contract could not be renewed, I was glad to be in the comfortable position of having the position with Iscor in my pocket.

In short : it’s OK to fail, provided you learn from your mistakes. Which I hope I have done over the subsequent 30-odd years.