SEARCH · PubMed Health

Results for “Alloys”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed1979

[Studies on Pd base ternary alloys for dental amalgam. (Part 1) Effect of size and shape of particle on dimensional change and mechanical properties (author's transl)].

Although much efforts have been paid to improve the properties of silver-tin amalgam, some clinical problems are not resolved yet. Palladium alloys have good properties for dental material, and they react on mercury well. So they are considered to be good amalgam alloys. In this paper, palladium base ternary alloys are studied for dental amalgam. The effect of size and shape of particle on dimensional change, compressive strength and hardness is studied. Main results obtained are as follows. (1) The dimensional change of spherical particle amalgam is smaller than that of fine cut particle. The finer the particle size is, the smaller the dimensional change is both for spherical and fine cut particles. (2) The dimensional change of amalgam of 60 wt% Pd-40 wt% Ag alloy decreased by addition of Sn or Cu, and these values under 20 micrometer/cm by addition of more than 5 wt% Cu or 10 wt% Sn. (3) Compressive strength of Pd alloy amalgam scatter so widely that the effects of alloying element are not able to be evaluated. Both maximum compressive strengths are 22 kg/mm2 and 28 kg/mm2 for the alloys containing Cu and Sn respectively. (4) Vicker's hardness of palladium alloy amalgam increased by addition of Sn and ranged 80 approximately 120 for spherical amalgam, which is higher than that of commercial alloy. Significant difference is not found in Cu added alloys. (5) From the analysis by XMA, it is found that matrix is composed of one phase and there is compositional difference between center of matrix and near the particle. Silver is rich in the center of matrix and palladium is rich near the alloy particle. Cu and Sn are seemed to distribute uniformly.

Dental Amalgam↗

PubMed1977

Bond strength studies of precious, semiprecious, and nonprecious ceramic-metal alloys with two porcelains.

One-hundred cylindrical pull-through ceramic-metal test specimens were subjected to shear loading forces. Two porcelain systems were treated in association with five ceramic alloys--one precious, one semiprecious, and three nonprecious alloys. 1. There was no significant difference in bond strength between Ceramco and Vita porcelains. 2. The various alloys tested demonstrated significantly different bond strengths. 3. Differential statistical tests suggested that nonprecious alloys performed better with Ceramco porcelain than with Vita porcelain. 4. The bond strength of Ceramco porcelain fused to nonprecious alloy N-C2 was significantly greater than that of Ceramic and traditional gold-based alloys. 5. Nonprecious alloy N-C1 produced significantly less bond strength than the traditional gold-based alloys. 6. Semiprecious alloy W produced high bond strengths with both Ceramco and Vita porcelains. 7. The cylindrical pull-through test was a reliable, reproducible method of testing ceramic-metal bond shear strength. 8. The surface roughness appears to be the one common factor in nonprecious alloys that relates to large differences in bond strength. Additional tests must be made to verify this hypothesis.

Ceramics↗

PubMed1978

[Studies on dental casting ferromagnetic alloys (author's transl)].

We previously reported successful applications of rare earth-cobalt magnets to dental prostheses. In order to use magnets more effectively, ferromagnetic materials with a high magnetic permeability and a high saturation flux density should be used as prosthetic materials. This type of material will form a good magnetic path, and consequently tighten the magnetic attracting force by preventing the magnetic flux from leaking into the mouth tissue. A few alloys were newly prepared by using Pd, Co and Cr, the usual dental metals, and tested. It was found that: (1) These alloys have suitable magnetic properties. (2) The corrosion resistances of the Pd-Co and Pd-Co-Cr alloys are as good as those of dental casting Ag and Ni-Cr alloys, respectively. (3) The physical and mechanical constants of the alloys are similar to those of the usual dental casting alloys. (4) These alloys can be used as dental casting ferromagnetic alloys. (5) The Pd-Co alloy can also be used as a porcelain bonding alloy.

Cobalt↗

PubMed1977

Semiprecious alloys for cast restorations: a preliminary report.

A previous clinical evaluation indicated that semiprecious metals had a definite place in the construction of dowels and cores in endodontically treated teeth. 2 The results from the present in vitro study suggest that those alloys do have a place in the fabrication of single castings as type III and IV gold alloy substitutes. Although when compared with a type III gold alloy the behavior of the semiprecious alloys tested was less like that of a noble alloy, the semiprecious alloys appeared less active than the base-metal alloy. This suggests that the semiprecious alloys should be acceptably resistant to corrosion in the oral environment.

Crowns↗

PubMed1978

[Aging properties of indium added gold alloys for metal-ceramic system (author's transl)].

Aging properties is studied on Au-10 wt% Pt and Au-10 wt% Pt-0.5 wt% Fe alloys containing 0.2, 0.4 and 2.0 wt% Indium. The results obtained are as follows: 1) In added Au-Pt alloys. From the electrical resistances in the isochronal aging curves, 0.2 and 0.4 wt% Indium added alloys are age-hardenable between 350 degrees and 640 degrees C. Heterogeneous phase in founded in 2.0 wt% Indium added alloy by meanes optical microstructures. This phase is identified fcc Pt3In by meanes X-ray diffraction. 2) In added Au-Pt-Fe alloys 0.2, 0.4 and 2.0 wt% Indium added alloys are age-hardenable between 250 degrees and 620 degrees C. Grain boundary reaction accelerated in 2.0 wt% Indium added alloy, and hardness decreased by overaging. Precipitation of nodule is inhibited in 0.2 wt% Indium added alloy, and aging properties also increase.

Ceramics↗

PubMed1977

A comparison of the casting ability of precious and nonprecious alloys for porcelain veneering.

The alloys tested varied with respect to their castability. This variability is related to density. Problems caused by low density may be solved by increasing the casting force. For all parameters measured in the laboratory, Thermocraft, a precious alloy, proved to be the most satisfactory- Wiron S, a nonprecious alloy, was comparable to Degudent Universal, a gold alloy. The application of Wiron S as a successful gold substitute should, therefore, be further investigated clinically. Equipment, investment, and casting techniques, all designed for the casting of gold alloys, were also used for the nonprecious alloys. These are standard facilities readily available in clinical practice. Modifications or technical improvement to these factors may result in more successful application to the other nonprecious alloys.

Dental Alloys↗

PubMed1977

Wetting of amalgam alloys by mercury.

The degree of wetting of amalgam alloy by mercury during trituration is an important variable in determining reaction rates and the degree of amalgamation. The purpose of this study was to measure the contact angle made by mercury on various phases present in amalgam alloy in air and on commercial alloys. During amalgamation, mercury is in contact with the oxides present on the amalgam alloy as well as the metallic amalgam phase. To measure the degree of wetting of the metallic phases, silver, tin, and copper were melted in such proportions as to give specimens of silver, tin, the alpha, beta, and gamma silver-tin phases, the eutectic in the silver-copper system. These were cast in the form of cylinders, sectioned, and the surfaces prepared by sandblasting. Oxide specimens of AgO, Ag2O, SnO, and SnO2 were prepared by compaction in a mold. Four commercial amalgam alloys also were tested. Mercury drops were then placed on the surfaces and the contact angles measured at different time intervals. The initial contact angles of mercury on the alpha, beta, gamma, and eutectic phases were found to be 90degrees, 112 degrees, 145 degrees, and 138 degrees, respectively. Mercury reacted with silver and tin, resulting in a change of contact angle with time. Contact angles measured on the commerical alloys were also high, on the order of 145 degrees. The gamma phase had contact angles closest to those of commercial alloys. Surface oxide phases are most likely responsible for this poor wettablility by mercury.

Copper↗

PubMed1978

Powder data file as a tool for identification of dental gold alloys.

In order to obtain data for a prospective powder data file for dental gold alloys X-ray diffraction photograms of 75 different gold alloys were taken using a Guinier-Hägg camera and CuKalpha1 radiation. Before the X-ray photograms were taken the alloys had been heat treated at 700 degrees C, 800 degrees C or 900 degrees C depending on the solidus temperatures of the alloys. The lattice parameters of the samples were determined from the X-ray photograms. These data were supplemented by a specification of the interplanar spacings of the three strongest lines on the diffraction patterns and also by the relative intensities and Miller indices of these lines. An extensive library of reference films is to be collected and this and other details of the file are discussed. It is not intended that the file be used to identify a particular alloy but merely to identify the type of alloy. Thus it can serve as a guide to facilitate the proper selection of gold alloys within practical clinical dentistry.

Filing↗

PubMed1978

[X-ray diffraction at the metal-ceramic interface. (Part 2) Surface oxides of 88% Au alloys containing Fe, In, Sn for porcelain fusing (author's transl)].

Fifteen alloys were prepared by adding 0-1.00 wt% Fe, In and Sn (total amount 1.00 wt%) to 88 Au -6 Pt-5Pd-1 Ag master alloy. Before and after the degassing process, the surfaces of these alloys were examined by X-Ray diffraction technique. The crystal structure and the amount of the surface oxides which were formed after the degassing process were determined, and their influence on bond strength between alloys and porcelains was discussed. The results obtained were summarized as follows; 1) In all alloys nonprecious elements were oxidized selectively after the degassing process. 2) On the surface of the alloy to which only Fe, In or Sn was added, Fe2O3, In2O3 or SnO2 was formed respectively. 3) In most cases when two or three nonprecious elements were added together, the above mentioned oxides were formed in mixture. However, something different from them was observed in some of the alloys tested. 4) Quantity of each of the oxides formed was not always in proportion to that of the additives. 5) The lattice parameters of the oxides were depended on the concentration of the additives.

Dental Bonding↗

PubMed1979

A quantitative and subjective characterization of tarnishing in low-gold alloys.

1. The quantitative objective characterization of tarnish gave results which are identical with those obtained from a blind subjective analysis. 2. The low-gold alloys fall into three classes. The alloy Ney Cast III is superior in performance to the other low golds and approximately equivalent to the high-gold alloy Firmilay. The intermediate alloys, including Midacast, Stabilor G, Mowrey No. 46, Tiffany, and Midas are similar in performance to the high-gold alloy Rx O.R.Y. The low-gold alloys Dent Cast 44, Minigold, and Progold tarnish in a manner which, in our opinion, makes them unacceptable.

Dental Alloys↗

PubMed1979

A survey of the elemental composition of alloy for dental amalgam.

Analyses of 51 alloys (conventional, 41, and high-copper, 10) currently available in Australia were made. A rapid and precise procedure was developed that relied on wet-way methods for silver and tin while copper, zinc, mercury, indium and low-level constituents, such as lead, cadmium and antimony, were determined by atomic absorption spectroscopy. The conventional alloys, with two minor exceptions, all complied with the compositional requirements of modern standards and little quantitative variations was noted when the range of the major component was compared with the values obtained in two surveys made over thirty years ago. The high-copper contained, among other factors, an average copper concentration about four times that of conventional alloys. Rather surprising were the contents of mercury, indium, and cadmium found in some of the alloys as well as the low-level concentration of lead, and in a few cases antimony. Other elements were not detected by the sensitive technique used. It is justifiable to recommend that the maximum zinc content to be permitted in zinc-free type alloys should not be greater than 0.01%, and this value was subsequently incorporated in the revised Australian standard 2110-1977: Alloy for Dental Amalgam.

Antimony↗

PubMed1979

Oxidation of noble metal alloys for porcelain veneer crowns.

It has been found that oxide-forming elements in the alloy are important for the blood strength between the metal and the procelain. The purpose of the present investigation was to study the formation of oxides during pretreatment and firing of porcelain. Four commerically available Ceramo-Metal alloys were studied. The specimens were heated at 980 degrees C for five hours in air, and the weight was continuously recorded. In addition porcelain was fired on to the alloys. Metallographic examinations were conducted on both oxidized and fired speciments. The weight gain data also indicated an increased oxygen uptake with a larger amount of oxidizable elements in the alloy. Most of the oxygen gain and time indicated that the oxygen uptake was diffusion controlled. The weight gain data also indicated an increased oxygen uptake with larger amount of oxidizable elements in the alloy. Most of the oxygen in the oxidize alloys was located as oxide along grain boundaries in the metal.

Crowns↗

PubMed1979

[Changes in the metallic phase at the metal-ceramic margin of baked alloys of nonprecious metals].

Five base metal alloys were investigated to determine if phase changes in the alloy microstructure occurred as a result of the porcelain baking procedure. It was found that during the oxidation treatments concentration changes in the alloy surface led to a depletion of certain elements in four of the alloys investigated. It was also found that phase changes could occur in a region 20 micrometers wide next to the alloy surface. Phase changes and alloying element depletion occurs as a result of the oxidation treatments prior to the fusion of porcelain and not as a result of or during porcelain fusion.

Acid Etching, Dental↗

PubMed1977

COP, a new alloy for surgical implants.

Today Vitallium is used for surgical implants. It is a casting alloy which, with advances in casting technology, is also used commercially for making instruments of fairly complex shape. Because of its expense, however, it is not widely used in Japan. Instead, a series of 18-8 Mo alloys are used in Japan even though of insufficient strength. Used over a long period of time in the body, especially for the purpose of preserving structual functions as part of the human skeleton, it often corrodes, resulting in either abnormalities in tissue cells or, because of its insufficient strength, danger of bending and breaking with aging. In spite of a marked advance in fracture treatment, we have hardly any suitable materials for making instruments appropriate to the internal fixation of fractures in Japan. We, therefore, conducted various experiments to develop an alloy with sufficient corrosive resistance and strength that could be formed into a complex shape to take the place of Vitallium alloy, finally succeeding in developing an alloy we call "COP". The characteristic properties of COP may be summarized as follows: 1. The main components are 20% Cr, 20% Ni, 20% Co and 4% Mo aside from 0.2% P. 2. As it contains "P", it shows a marked age-hardening. In its molten state its machinability is excellent, and later it can readily be hardened by heat-treatment. 3. It has not only a marked yield point and tensile strength but also has toughness in elongation and reduction of area, showing a strength which surpasses Vitallium. 4. Its corrosive resistance is great. 5. Its cost is far cheaper than Vitallium.

Alloys↗

PubMed1979

[Investigation of Pd-Ag alloy for porcelain fusing. (Part 3) Mechanical properties (author's transl)].

The most suitable composition of Pd-Ag alloys added In and/or Sn for porcelain fusing was determined by means of the measurement of the mechanical properties (tensile strength, elongation and hardness). The results were summarized as follows: (1) This highest tensile strength was obtained when 5% In and 5% Sn, or 10% Sn were added to the 60 Pd-40 Ag mother alloy, and it was about 52 kgf/mm2 (570 MPa). (2) The effect of the addition of In and Sn to the tensile strength depended on the concentration of Pd and Ag. (3) The elongation increased with increase of the amount of Pd. (4) The Vickers hardness number of the alloys was ranged between 100 and 200. It increased with increase of Ag or Sn content. (5) The most suitable compositions of Pd-Ag alloys for porcelain fusing deduced from the properties such as the bonding strength (in part 1), the thermal expansion coefficient (in part 2) and the mechanical properties (in this paper) were 60 Pd-40 Ag or 64 Pd-36 Ag with addition of 4 Sn-6 In or 8 Sn-2 In. Some characteristic properties of these alloys were as follows; the bonding strength 220 kgf/cm2 (22 MPa), thermal expansion coefficient 14.7 +/- 1x10(-6)/degrees C, thermal expansion hysteresis. 0.00 approximately 0.02%, tensile strength 51 kgf/mm2 (500 MPa), elongation 5% and Vickers hardness number 160 approximately 190.

Dental Alloys↗

PubMed1977

Galvanic series of some dental alloys.

Galvanic series for different metals in different electrolytes have been published, but never for dental alloys in artificial saline solution. The material classes studied are amalgam, gold alloy, nickel alloy, chromium cobalt casting alloy and temporary crown form. The electrogalvanic potentials were measured and determined in reference to a hydrogen electrode (H2/H+) arbitrarily defined as zero. A galvanic series of the tested materials was arranged in order of their potentials.

Chromium Alloys↗

PubMed1977

Hardening of gold-based alloys.

The relationships between composition, heat treatment, hardness, and microstructure have been investigated for a number of commercial dental casting alloys and for several series of experimental gold-silver-copper compositions. The hardnesses and typical microstructures found are reported. The results indicate that at least two distinct hardening mechanisms must occur in these alloys. The ternary alloys outside the two-phasr region of the gold-silver-copper system harden by ordering. The commercial alloys and those within the two-phase region may harden in part by ordering, but some other mechanism in required to explain the observed hardening. This mechanism is not due to the observed grain boundary precipitates. It may be associated with the intragranular needlelike structures seen, but reasons exist to question the sufficiency of that structure as an explantation of the hardening.

Copper↗

PubMed2026

Study of the densification mechanisms of Al-Fe-Cr-Ti alloys during high-velocity compaction based on 3D MPFEM.

Aluminum alloy materials are widely used in aerospace and related fields, among which Al-Fe-Cr-Ti alloys have attracted increasing attention owing to their low density and excellent comprehensive properties. However, the densification mechanisms of alloy powders during high-velocity compaction (HVC) remain insufficiently understood. In this study, a three-dimensional multi-particle finite element method (3D MPFEM) model was developed to simulate the HVC process of Al-Fe-Cr-Ti alloy powders and to evaluate the effects of friction coefficient μ, impact energy per unit mass Em, hammer mass M, and compaction velocity v on powder densification. The results show that increasing μ from 0.25 to 0.65 reduced kinetic-energy transfer and stress transmission, decreasing the relative density ρ of the green from 0.7076 to 0.6797. In contrast, increasing Em from 55.58 to 144.67 J/g markedly improved densification, with the maximum relative density reaching 0.8881. Displacement-field analysis further revealed that appropriate combinations of M and v promote particle rearrangement and plastic deformation. Experimental validation confirmed that the simulated density evolution agreed well with the measured trend, although the predicted values were slightly lower. These findings indicate that 3D MPFEM can reasonably describe the macroscopic densification trend and provide qualitative particle-scale insights into deformation and energy-transfer behavior during HVC.

3D MPFEM↗