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At least 19 recordsLinked to original sources
PubMed1979

[Study of gold-nickel alloy. (Part 1) The properties of gold-nickel binary alloys (author's transl)].

To research the possibility of a new dental Au base alloy, Au-Ni alloys were examined. Comospitions were 82.5% Au-17.5% Ni alloy, 77% Au-23% Ni alloy and 70% Au-30% Ni alloy. Mechanical properties of these alloys were equal to those of hardened Au added Pt alloy or type IV Au alloy. And these alloys have shown no tarnish and corrosion in 0.1% NaS solution, 0.05% HC1 solution or 1% Lactic acid solution after 21 days. Especially 77% Au-23% Ni alloy was the best among them.

Corrosion↗
PubMed1979

Evaluation of alternative alloys to precious ceramic alloys. 1. Mechanical properties.

In the first part of this study, the microstructures and the mechanical properties of precious, semi-precious, and nonprecious dental casting alloys for the porcelain-baked-to-metal technique have been determined. The semi-precious alloys contained only 50% gold, and palladium, silver, and some base metals. The nonprecious alloys were of the nickel-chromium type. Discs and miniaturized tensile bars have been cast and tested either in the as cast condition, or after a simulation of the various porcelain bakes. Proof stress, ultimate tensile strength, elongation, and plastic stiffness have been measured and results compared by use of analyses of variance. The microstructure examination shows that the simulation of the porcelain bakes improves the homogeneity of the precious and semi-precious alloys. Simultaneously, the mechanical properties of the same alloys are also improved. One semi-precious alloy, still under development at the time of these tests, has its mechanical characteristics markedly downgraded by the thermal treatments. The nickel-chromium alloys exhibit the best range of mechanical properties for the porcelain-baked-to-metal technique, when considering the three most relevant properties: proof stress, plastic stiffness, and modulus of elasticity.

Chemical Phenomena↗
PubMed1979

[Casting of dental alloys with special reference to the bonding capacity of Ni-Cr alloys].

A short review on castability of dental alloys -- for which a definition is proposed -- reflects the different factors influencing the results of a casting. In this case solid sieves and plates are cast by use of one gold-base alloy (Type III) and two base metal alloys used for porcelain veneering. All three alloys filled the sieve pattern to a 100%, whereas they performed differently when cast as thin, solid squares. The most continuous results were achieved with a Ni-Cr-alloy whose melting temperature can be recognized since the ingots flow together when this point is reached. Since the plate pattern is most difficult to cast due to surface to bulk ratio it is assumed that a complete casting can only be achieved when the performance of the alloy is good and all required conditions match. Thus, this type of test seems to be suitable to determine the castability of a dental alloy. The sieve test should be used to investigate and to improve the influence of the different factors as for example burnout time and temperature of the mold and sprue size.

Chromium↗
PubMed1977

[Bond strength between nonprecious metal alloy and porcelain. (Part 2) Effects of the addition of Mn, Mo, Si, Sn, Ta and Ti on bond strength of 80 Ni-20 Cr alloy (author's transl)].

Alloys added 2, 4 and 6 wt% Mn, Mo, Si, Sn, Ta and Ti to 80 wt% Ni-20 wt% Cr alloyand no-added 80 wt% Ni-20 wt% Cr alloy were prepared and casted to obtain the test specimens 3 mm in diameter 25 mm in length. Ceramco porcelain (B.F. Vacuum Porcelain) was fused to each of these specimens, and the bond strength was measured by the pull-out method which applies shear stress to the metal/porcelain interface to investigate the effect of each addition element. The test results may be summarized as presented below. 1) The bond strength between the 80 Ni-20 Cr alloy and the porcelain was 182 +/- 14 kg/cm2. 2) Of the six kinds of addition elements, it was Mo, Sn, Ta and Ti that increased the bond strength. 3) The bond strength between the alloy added 6 wt% Ti to the 80 Ni-20 Cr alloy and the porcelain was 319 +/- 8 kg/cm2, which was increased by about 75% over the strength between the 80 Ni-20 Cr alloy and the porcelain.

Chromium↗
PubMed1977

Porosity in base metal partial denture casting alloys, related industrial alloys, and pure metals.

Two types of specimens were cast from a variety of pure metals and alloys. A unidirectional solidification system was used for the production of the first, whilst a deliberate feeding problem was incorporated in the production of the second. The specimens were subjected to radiographic and metallographic evaluation in conjunction with porosity determinations, in order to ascertain how the amount and pattern of porosity varied with alloy complexity and alloy composition.

Absorptiometry, Photon↗
PubMed1979

[Studies on Au-Ag-Pd-Cu alloys. (Part 1) Effects of Au component on some properties of alloys (author's transl)].

Au-Ag-Pd-Cu quaternary dental alloys were studied to find out the more favourable Au content. Pd and Cu content were fixed to 20 wt% respectively but Au content were changed from 10 wt% to 40 wt% and Ag content were balanced. Tensile, hardness, corrosion and castability test were carried out. Results were as follows. 1) The tensile strength and elongation of swaged specimen showed highest value at 30 wt% Au but in case of casted specimen, tensile strength was highest as 20 wt% and elongation was minimum at 30 wt% Au. Those differences between swaged and cast specimens were seemed to depend on the casting porosities. 2) The Vickers hardness test showed that the hardness gradually increased with Au content and showed the highest value at 30 wt% Au. 3) The corrosion test in the 0.1% Na2S solution indicated that the corrosion resistance was increased with Au content but the rate of increment was slow down at 30 wt% Au. 4) The castability test showed that no significant difference was found out one another. These experimental results seemed to indicate that 30 wt% Au was the favourable composition for Au-Ag-Pd-Cu dental alloys.

Copper↗
PubMed1979

The influence of heat treatments on several types of base-metal removable partial denture alloys.

Four removable partial denture alloys, Vitallium (Co-Cr alloy), Dentillium P.D. (Fe-Cr alloy), Durallium L.G. (Co-Cr-Ni alloy), and Ticonium 100 (Ni-Cr alloy), were evaluated in the as-cast condition and after heat treatment for 15 minutes at 1,300 degrees, 1,600 degrees, 1,900 degrees, and 2,200 degrees F followed by quenching in water. The following properties were determined and compared for each alloy at each heat treatment condition: the yield strengths at 0.01%, 0.1%, and 0.2% offsets, the ultimate tensile strength, the percent elongation, the modulus of elasticity, and the Knoop microhardness. The results were statistically analyzed. Photomicrographs were examined for each alloy and test condition. The following conclusions were made: 1. The "highest values" were exhibited by the as-cast alloy. 2. Heat treatment of the partial denture alloys tested resulted in reductions in strength, while the elongations varied. This study demonstrates that, in practice, one should avoid (a) prolonged "heat-soaking" while soldering and (b) grinding or polishing of the casting until the alloy is "red hot". 3. Durallium L.G. was the least affected by the various heat treatment conditions. 4. Conventional reporting of the yield strength at 0.2% offset, the ultimate tensile strength, and percent elongation are not adequate to completely describe and compare the mechanical behavior of alloys. The reporting of the yield strength at 0.01% offset, in addition to the other reported properties, will provide a more complete description of the behavior of the dental alloys.

Chromium↗
PubMed1977

[A study on the effects of beryllium addition upon biological and physical properties of dental cobalt-chromium alloys (author's transl)].

The effects of beryllium addition to a dental cobalt-chromium alloy on biological compatibility as well as physical properties were examined and the following results were obtained. 1. Slight, but significant depression of the rates of cell multiplication was obtained with the experimental groups, i.e., alloy with no beryllium added as well as alloys with beryllium of up to 3.0 per cent by weight, compared to control group, which contained no alloys, but a glass disk. Within the experimental groups no significant difference in the rates of cell multiplication was found between the alloys with beryllium addition ranging from zero up to 2.0% by weight. However, alloy with 3.0% beryllium yielded slight, but significant depression of the rates of cell multiplication. Pure beryllium metal revealed severe cytotoxicity. 2. Cell morphology of the experimental groups confirmed the above results of the rate of cell multiplication. 3. Increase of beryllium within the alloys resulted in increase of tensile strength as well as Rockwell hardness, while elongation and fusion temperature were brought down. 4. Metallographs of alloys and cast specimens confirmed the results of the mechanical properties. The more beryllium was added, the smaller was the alloy crystal observed. 5. Loss of beryllium in the alloy was found during such procedures as melting each metal for making up alloys and casting. It is considered that the present results will be able to lend suggestions to beryllium use in dentistry with regard to biological compatibility as well as physical properties.

Animals↗