There are multiple grades of MoSi2 elements. The purer the element, the better the grade. SiC Elements tend to have a lower temperature capability, but require replacement more often than MoSi2. Your application is important. 1450 Sintering...fine use SiC. 1500 or higher use MoSi2. The better quality you pay for, the less problems you'll have. BTW Sam, the monthly "regeneration" cycle is not a purge as much as an oxidation removal from the surface Silica layer on the MoSi2. But I understand why you think of it as contamination and purge. It bares some similarity. If it goes on too long, it will become a contaminate. However, that being said MoSi2 elements far outlast SiC and as long as you care for them properly they will blow away a SiC oven any day.
However, prices for ovens containing either element vary greatly.
The problem with SiC elements is that they are wired in parallel because their resistance changes over time. This is the reason ALL or PAIRS of SiC elements must be replaced when a sintering oven with SiC elements goes down. Furthermore they will go down much more quickly because their maximum SURFACE temperature is about 1600C. Making the maximum PROGRAMMABLE temperature of their respective ovens typically 1530C to 1540C. So when you are sintering that new translucent zirconia at 1530C, the element's surface temperature is 1600C. So you are redlining the elements every time you use them.
MoSi2 elements can be replaced individually as they tend to be wired in series and they maintain their electrical stability. The prices vary based on the grade of MoSi2 elements in your oven. But instead of 6 months to a year of life (Like SiC),you'll get multiple years. Their maximum surface temperature range from 1750C to 1900C. The programmable temperature depends on the oven manufacturer, insulation and thermocouple type used.
While these elements have a reputation as a contaminator, the fact is most of the people in this industry had no idea how to maintain or the will to maintain their ovens. All you have to do is run the REGENERATION cycle periodically. Monthly is fine, some once a quarter is enough. But you have to pay attention. There 5 year old ovens that have the same elements and are working everyday.
Pre-shaded zirconia took away a lot of the alkali problems associated with MoSi2 elements, but even for those still using color liquids, there are clear protocols for maintaining sintering oven elements.
Big concerns now are power, sintering dishes and understanding protocol and the desire to accelerate the process. There are other major concerns guiding sintering ovens. But quality is imperative. Many manufacturers use many types of components. Study your elements, fine, but don't stop there. Did you know:
Different types of trays cause different types of results? This means you could use the wrong tray and get bad results, but the questions comes to bare, which tray to use?
Different types of thermocouples are available in different ovens? This means quality and consistency! B or S....no BS! Lol - geak joke. Which is better type B or Type S....why...go find out!!!
Different voltages are available 220Vac, 115Vac and 408Vac.
I'm tired now...call me if you like, call Sam if you like. Either way it seems we both try to help, but if YOU do the homework. YOU will benefit more.
.
