Crucible Wall Damage

scarcius121

scarcius121

New Member
#1
I'm using a Vcella TL16 tilting furnace with a graphite crucible, idk if it has the same properties as the large crucible seen here.

http://www.lmine.com/mm5/merchant.mvc?S ... ng_furnace

I'm using the following in my melts of various copper alloys. Most alloys consist of either a copper zinc or copper lead variety.

Brass Flux Synex - BA315 - http://www.budgetcastingsupply.com/Brass_Flux.php
15% Phosphor Copper Shot - http://www.budgetcastingsupply.com/Phosphor-Copper.php
Brass Degasser - Asbury 761 - http://www.budgetcastingsupply.com/Brass_Degas.php

I put in some Flux at the start before a charge is added to help the metal form a heel. After the metal is melted I add some Phosphor shot, Flux, then degasser, then pour. However, I was shipped something that was suppose to be Brass Degasser - Asbury 761 but it may have been plumbago I simply cannot tell the difference it does react in the furnance as the degasser should. When I am done with my furnance I am noticing a thick black substance on the crucible walls, that when I touch it flakes off. It looks almost like sweat on the inside of the crucible. The crucible has about 12hrs use on it. It looks like it may last 30-50hrs total. The outside of the crucible is 100% ok, the inside is looking like 75-80% ok it just looks like it needs to be cleaned and then patched in some ways or coated to prevent this from happening anymore.

Possible Solutions: (Which should I do?)

Cut down on amount of flux, and degasser used.
Use ITC 213 on the inside of the crucible. The same stuff I coat my skimmers with - http://www.budgetcastingsupply.com/ITC.php
Try using some Buffalo Patch on the inside of the crucible - http://www.lmine.com/product/17152X.html

Also what should I do to a new crucible to help it out and prevent chemical damage to it?

How do I clean the inside of the crucible without damaging it, and with what?
 
fireguy

fireguy

Supermoderator
#2
scarcius121:
Make sure you are preheating the new crucible to drive of any moisture that may have been absorbed over time or in shipping.

You can coat the inside of the new crucible by firing some borax. This will give a glassy coating to the inside of the crucible. Personally, I don't relly think this will extend the life of the crucible, but some people think so and do this.

I don't know what those products you mention are. Often times excessive crucible wear and erosion are a function of flux deficiencies. For instance, if you are silica deficient in your flux, silica will be robbed out of the wall of the crucible and shorten the life.

Buffalo type patch if used on silicon carbide crucibles to "glue" on the spouts, and also for some repair. This may or may not work the same on graphite crucilbes (I think it probably will). Give it a try, use "less" as opposed to "more". Make it as dry as possilbe, and tamp it into place.
 
Top