On 12/30/2009 1:31:00 PM, wzelik wrote:
>Dear Richard
>I'm refractory engineer. My
>factory have produced
>basic refractory material,
>mainly for steel
>industry. I'm interesting in
>corrosion model and
>direct dissolution in the
>higher temperature is
>very important factor.
>Corrosion of refractory
>materials is very complex
>problem depending on
>many factors and I try to
>describe one of them.
>For example in the steel ladle
>we have slag from
>CaO-Al2O3-SiO2 system.
>Typically in the slag zone
>we recommend MgO-C materials.
>Because inside the
>bricks we have carbon,
>infiltration of slag is
>limited. Chemical reaction
>between material and
>slag is rather surfacing (of
>course when we have
>small oxygen partial pressure)
>and direct
>dissolution has great
>importance.
That's all very interesting, but I think you misunderstand what I am asking about. It is possible to provide a curve, described by an equation of some sort, that models your data. There are many ways to do that though, and the best choice depends on what you want to use the resulting equation for. In Study's worksheet there are a couple of pertinent examples. One is to interpolate using a cubic spline. That will produce a curve that is guaranteed to go through every point (it is an interpolation, not a least squares fit). However, it has as many coefficients as there are points in the curve, so although you have an equation that can be used (for example) to find values at intermediate CaO/SiO2 ratios, you do not have some simple looking equation that you can easily write on a piece of paper. Splines actually don't like discontinuities in the data either, and interpolated values close to them may be way off. What Study has posted is a good start, but it would probably need to be modified. Another approach is to fit a rational polynomial to the data (rational polynomials can handle discontinuities very well). That is a least squares fit, and will not pass exactly through every point. You might get a decent fit with relatively few coefficients though, so you might get a fairly simple expression. Neither of the above equations will tell you anything about the physics or chemistry of the system, but they may be useful to you anyway, depending on what you intend to use the equation for. But that's the question: what are you intending to use it for? Do you just want to interpolate the existing data (spline or linear interpolation are probably the best bets)? Or find an equation that you could somehow use in a process control system (splines would probably have too many coefficients, but the rational polynomials might work)? Or to try to find the phase boundaries from the equations (in which case this is probably not be the best approach at all)? Or something else?
>Forgive me question, but have
>you ever analyzed
>ternary phase diagram?
I've used them. What exactly do you mean by "analyzed" though? Analyzed in what way?
>Besides i'm sorry for my
>english.
It seems good enough to me 🙂
Richard
