Abstract
A comparison was made of the effect of different metal surface treatments on the fusion of metal to porcelain.
The following results were obtained.
1. For surface treatment of the metal, usually we followed the following procedures: casting, pickling (HF acid), degassing and then secondary pickling.
Instead of the secondary pickling step, we also tried a sand-blasting technique.
The latter resulted in a greater degree of fusion than the usual procedure.
2. No matter how the surface treatment was done by any method (Table 2), we learned that the degree of fusion was larger when sand blasting, rather than pickling, followed the degassing procedures.
3. The greatest degree of fusion occured with pickling and sand-blasting.
4. In the case where polishing followed sand-blasting (Table 2, # 3) only 1/2 the degree of metal to porcelain fusion was obtained in contrast the other methods.
5. From on data, fusion between porcelain and metal appears to be greatest when the degassing step is included. And this may be due to the formation of an oxidized film. From this information a stronger degree of fusion may be expected by a chemical-bonding system.
6. If a chemical that could remove the residual investment material quickly was used in combination with supersonic cleaning, then it is not necessary to use the HF acid (pickling step).
7. An optical microscopic examination of the porosity condition of the metal surface revealed that the degassing was not able to restrain bubble formation.
8. Two metals used in this experimental alloy were In and Sn. From the results of quantitative analysis, the ratio of these metals which exuded on to the metal alloy surface was 2: 1.
