Development of casting investment preventing blackening of noble metal alloys part 3. Effect of reducing agent addition on the strength and expansion of the investments.
Different reducing agents (B, Al, Si and Ti) were individually added to two gypsum-bonded investments to prepare investments preventing surface blackening of some noble cast alloys. The effect of different additive contents on green-body and burnout compressive strength, setting and thermal expansion of the investments were evaluated. The strength and expansion of the investments were changed by the additives. The compressive strength of Al-, Si- and Ti-added investments decreased with the increase of additive contents. The burnout strength of B-added investments significantly increased while green-body strength remained unchanged. The setting expansion of the B-added investments increased while those of the Al-, Si- and Ti-added investments decreased with the increase of additive contents. The thermal expansion of the Si- and Ti-added investments decreased, and that of the Al- and B-added investments remained unchanged. Further study is necessary to evaluate the effects of these additives on the accuracy of dental castings.
Department of Dental Materials Science, School of Dentistry at Niigata, The Nippon Dental University, Hamaura-cho, Niigata City, Niigata, Japan.
Yukun
Y
Meng
Akira
A
Nakai
Hideo
H
Ogura
D000535:Aluminum; D000704:Analysis of Variance; D001895:Boron; D002133:Calcium Sulfate; D019245:Compressive Strength; D003300:Copper; D003722:Dental Alloys; D003734:Dental Casting Investment / Q000737:chemistry*; D004055:Differential Thermal Analysis; D006358:Hot Temperature; D008422:Materials Testing; D019163:Reducing Agents; D012825:Silicon; D012822:Silicon Dioxide; D018709:Statistics, Nonparametric; D014025:Titanium
C120982:Ag-Pd-Cu-Au alloy; D003722:Dental Alloys; D003734:Dental Casting Investment; D019163:Reducing Agents; D012822:Silicon Dioxide; D003300:Copper; D000535:Aluminum; D014025:Titanium; D001895:Boron; C030973:cupric oxide; D002133:Calcium Sulfate; D012825:Silicon