Instrument grades I-70A 99.0 0.7 700 700 1000 700 700 400 O-50 99.0 0.5 700 700 1000 700 700 400 I-220B 98.0 2.2 1000 1500 1500 800 800 400 I-400B 94.0 4.25 min 1600 2500 2500 800 800 400 Structural grades of beryllium are indicated by the prefix S in their designations. Property requirements for commercially available structural grades are presented in Table 3. In general, these grades are produced to meet ductility and minimum strength requirements. S-200F, an impact-ground powder grade, is the most commonly used grade of beryllium. This grade evolved from S-200E, which used attritioned powder as the input material. Recently, S-200FH has been introduced to the marketplace; the suffix H designates consolidation by HIP. The properties of S-200F include a minimum ductility of 2% elongation in all directions within the vacuum-hot-pressed billet, an increased of 1% over its predecessor, S-200E. In addition, S-200F has yield and ultimate strengths that are somewhat higher than those of S-200E, reflecting the general improvements in powder-processing techniques and consolidation methods. Table 3 Mechanical property requirements for structural grades of beryllium 0.2% yield strength Ultimate strength Grade MPa ksi MPa ksi Elongation, % S-65B 207 30 290 42 3.0 Grade S-65 also is an impact-ground powder product. This grade was formulated to meet the damage tolerance requirements for use in the Space Shuttle. Grade S-65 sacrifices some strength for improved ductility. The 3% minimum ductility requirement is achieved by using impact-ground powder in combination with tailored heat treatments. The heat treatments produce a desirable morphology of iron-aluminum-beryllium-base precipitates. Low levels of iron and aluminum are present in commercial grades of beryllium (see Table 2). Although these elements cannot be eliminated economically, they can be balanced, and heat treatments can be applied to form discrete grain- boundary precipitates of AlFeBe 4 . This minimizes the iron in solid solution or in the compound FeBe 11 , either of which is embrittling. The precipitates also eliminate aluminum from the grain boundaries, thus precluding hot shortness at elevated temperatures. At moderate temperatures, beryllium develops substantial ductility. At 800 °C (1470 °F), for example, the elongation of S-200F is in excess of 30%. Yield strength and ultimate strength decrease with increasing temperature, but usable strength and modulus are maintained up to approximately 600 to 650 °C (1100 to 1200 °F). The changes in strength and ductility of S-200F with temperature are shown in Fig. 4. Fig. 4 Tensile properties of S-200F beryllium at elevated temperatures Instrument grades of beryllium, which are designated by the prefix I, were developed to meet the specific needs of a variety of precision instruments. These instruments generally are used in inertial-guidance systems where high geometrical precision and resistance to plastic deformation on a part-per-million scale are required. The resistance to deformation at this level is measured by microyield strength. In addition to those grades developed to meet the needs of inertial guidance systems, grade I-70 was developed specifically for optical components is satellite imaging systems. Because the large mirrors used in aerospace optics must retain precise geometry throughout complex loading spectra, no differentiation was drawn between grades used for optical instruments and those used for inertial-guidance instruments. Recently, however, O-50, a grade developed specifically for the qualities of infrared reflectivity and low scatter has initiated the use of the prefix O to indicate an optical grade. The property requirements for commercially available instrument grades are given in Table 4. Table 4 Mechanical property requirements for instrument grades of beryllium 0.2% yield strength Tensile strength Microyield strength Instrument grade MPa ksi MPa ksi Elongation, % MPa ksi I-70A 172 25 240 35 2.0 . . . . . . O-50 172 25 240 35 2.0 . . . . . . I-220B 275 40 380 55 2.0 34.5 5 The property requirement that differentiates instrument grades from structural grades is microyield strength. In I-400, ductility has practically been ignored in order to attain microyield strength values of 60 to 70 MPa (9 to 10 ksi). Grade I- 220 strikes a balance between ductility and microyield strength, with a 2% elongation requirement and a microyield strength of 35 to 40 MPa (5 to 6 ksi). As greater insight into the relationship between properties and powder processing, composition, and heat treatment is obtained, further property improvements should be made possible. Wrought Products and Fabrication. Consolidated beryllium block can be rolled into plate, sheet, and foil, and it can be extruded into shapes or tubing at elevated temperatures. At present, working operations typically warm work the material, thereby avoiding recrystallization. The strength of warm-worked products increases significantly as the degree of working increases. The in-plane properties of sheet and plate (rolled from a P/M material) increase as the gage decreases, as shown in Table 5. As with most hexagonal close-packed materials, it develops substantial texture as a result of these working operations. The texture in sheet, for example, generally results in excellent in-plane strength and ductility, with almost no ductility in the short-transverse (out-of-plane) direction. Similar property trade-offs resulting from the anisotropy caused by warm working are inherent in extruded tube and rod. Sheet can be formed at moderate temperatures by standard forming methods. For some special applications, there has been interest in the improved formability of ingot-derived rolling stock as opposed to material rolled from a block of P/M materials. The ingot-derived stock has improved weldability and formability, primarily because of its reduced oxide content. Table 5 In-plane properties of beryllium products rolled from a P/M source block Thickness 0.2% yield strength Ultimate strength mm in. MPa ksi MPa ksi Elongation, % 11-15 0.45-0.60 275 40 413 60 3 6-11 0.25-0.45 310 45 448 65 4 In many instances, complex components must be built up from shapes made from sheet and foil. For example, beryllium honeycomb structures have been made by brazing formed sheet, as have complex satellite structural components. Beryllium tubing made by extrusion has also been used in satellite components. Space probes such as the Galileo Jupiter explorer have used extruded beryllium tubing to provide stiff lightweight booms for precision antenna and solar array structures. Health and Safety Considerations Beryllium has been commercially produced for more than 50 years, and its toxicity has been recognized and successfully controlled for the last 30 years. Information on the toxicity of beryllium is contained in the article "Toxicity of Metals" in this Volume. The main concern associated with the handling of beryllium is the effect on the lungs when excessive amounts of respirable beryllium powder or dust are inhaled. Two forms of lung disease are associated with beryllium: acute berylliosis and chronic berylliosis. The acute form, which can have an abrupt onset, resembles pneumonia or bronchitis. Acute berylliosis is now rare because of the improved protective measures that have been enacted to reduce exposure levels. Chronic berylliosis has a very slow onset. It still occurs in industry and seems to result from the allergic reaction of an individual to beryllium. At present, there is no way of predetermining those who might be hypersensitive. Sensitive individuals exposed to airborne beryllium may develop the lung condition associated with chronic berylliosis. Exposure Limits. Two in-plant exposure limits have been set by the Occupational Safety and Health Administration to prevent beryllium disease. The first is a maximum atmospheric concentration of 2 μg/m 3 of air averaged over an 8-h day. The second is a short-exposure limit of 25 μg/m 3 of air for a duration of less than 30 min. The U.S. Environmental Protection Agency (EPA) has set a nonoccupational limit of 0.01 μg/m 3 of air averaged over a 1-month period outside of a beryllium facility. The EPA limits the emission of beryllium into the environment to 10 g in any 24-h period. To meet these requirements, beryllium producers must adhere to industrial-hygiene standards and use air pollution control measures when dusts, mists, and fumes might be created. Historically, these control measures appear to have been effective in preventing chronic beryllium disease. Precious Metals and Their Uses A.R. Robertson, Englehard Corporation THE EIGHT PRECIOUS METALS, listed in order of their atomic number as found in periods 5 and 6 (groups VIII and Ib) of the periodic table, are ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold. Atomic, structural, and physical properties of the precious metals, which are also referred to as the noble metals, are listed in Table 1. Additional property data can be found in the articles "Properties of Precious Metals" and "Properties of Pure Metals" in this Volume. Table 1 Selected properties of precious metals Value for indicated metal Property Platinum Palladium Iridium Rhodium Osmium Ruthenium Gold Silver Atomic number 78 46 77 45 76 44 79 47 Atomic weight, amu 195.09 106.4 192.2 102.905 190.2 101.07 196.967 107.87 Crystal structure (a) fcc fcc fcc fcc hcp hcp fcc fcc Electronic configuration (ground state) 5d 9 6s 4d 10 5d 7 6s 2 4d 8 5s 5d 6 6s 2 4d 7 5s 5d 10 6s 4d 9 5s 2 Chemical valence 2,4 2,4 3,4 3 4,6,8 3,4,6,8 1,3 1,2,3 21.45 12.02 22.65 12.41 22.61 12.45 19.32 10.49 Density at 20 °C (70 °F), g/cm 3 (lb/in. 3 ) (0.774) (0.434) (0.818) (0.448) (0.816) (0.449) (0.697) (0.378) 1769 1554 2447 1963 3045 2310 1064.4 961.9 Melting point, °C (°F) (3216) (2829) (4437) (3565) (5513) (4190) (1948) 1763.4 Boiling point, °C (°F) 3800 2900 4500 3700 5020 ± 100 4080 ± 100 2808 2210 (6870) (5250) (8130) (6690) (9070 ± 180) (7375 ± 180) (5086) (4010) Electrical resistivity at 0 °C (32 °F), μΩ· cm 9.85 9.93 4.71 4.33 8.12 6.80 2.06 1.59 Linear coefficient of thermal expansion, μin./in./°C 9.1 11.1 6.8 8.3 6.1 9.1 14.16 19.68 Electromotive force versus Pt-67 electrode at 1000 °C (1830 °F), mV . . . -11.457 12.736 14.10 . . . 9.744 12.34 (b) 10.70 (c) Tensile strength, MPa (ksi) 207-241 324-414 2070- 2480 1379- 1586 . . . 496 207- 221 290 As-worked wire (30-35) (47-60) (300- 360) (d) (200- 230) (d) (72) (d) (30-32) (42) 124-165 145-228 1103- 1241 827-896 . . . . . . 124- 138 125- 186 Annealed wire (18-24) (21-33) (160- 180) (120-130) (18-20) (18.2- 27) Elongation in 50 mm (2 in.), % As-worked wire 1-3 1.5-2.5 15-18 (d) 2 . . . 3 (d) 4 3-5 Annealed wire 30-40 29-34 20-22 30-35 . . . . . . 39-45 43-50 Hardness, HV As-worked wire 90-95 105-110 600- 700 (d) . . . . . . . . . 55-60 . . . Annealed wire 37-42 37-44 200-240 120-140 300-670 200-350 25-27 25-30 As-cast 43 44 210-240 . . . 800 170-450 33-35 . . . Young's modulus at 20 °C (70 °F), GPa (10 6 psi) 171 115 517 319 558 414 77 74 Static (24.8) (16.7) (75) (46.5) (81) (60) (11.2) (10.8) 169 121 527 378 . . . 476 . . . . . . Dynamic (24.5) (17.6) (76.5) (54.8) (69) Poisson's ratio 0.39 0.39 0.26 0.26 . . . . . . 0.42 0.37 (e) Source: Engelhard Industries Division, Engelhard Corporation (a) fcc, face-centered cubic; hcp, hexagonal close packed. (b) At 800 °C (1470 °F). (c) At 700 °C (1290 °F). (d) Hot worked. (e) Annealed. Precious metals are of inestimable value to modern civilization. Their functions in jewelry, coins, and bullion, and as catalysts in devices to control auto exhaust emissions are widely understood. But in certain other applications, their functions are not as spectacular and, although vital to the application, are largely unknown except to the users. Many facets of daily life and influenced by precious metals and their alloys. For example, precious metals are used in dental restorations and dental fillings (see the section "Precious Metals in Dentistry" in this article). Precious metal solders are used in dentistry and in the jewelry and electronics industries. Thin precious metal films are used to form the electronic circuits. Much of our clothing today is produced with the aid of precious metals that are used in spinnerettes for producing synthetic fibers. Precious metals perform as catalysts in various processes; for example, widely used agricultural fertilizers are produced with the aid of a platinum-rhodium alloy catalyst woven in the form of gauze, and auto emissions are reduced through the use of platinum-group alloy catalysts. Electrical contacts containing palladium are essential to telephone communications. Certain organometallic compounds containing platinum are significant drugs for cancer chemotherapy. Resources and Consumption Metal specialists at the U.S. Bureau of Mines continually survey the market in silver, gold, and platinum-group metals to determine present availability and usage and to forecast future trends. Mineral Commodity Profiles and Mineral Industry Surveys covering these metals are issued periodically. Much of the information in this section was obtained from Ref 1, 2, 3, 4, 5, 6, 7, and 8. For the latest available information concerning these metals, it is recommended that the most recent issues of these publications be consulted. Silver. In recent years, the United States has been a net importer of silver. Imports, including unrefined silver, supplied about 89 million troy ounces of silver to the U.S. supply in 1988. Domestic mine production added 53 million troy ounces to this total, and refining of old scrap increased the U.S. silver level to a total of approximately 217 million troy ounces during this same period. The U.S. supply is obtained from primary and secondary sources. About 25% of primary silver is obtained from predominantly silver ores; the remaining primary silver is a by-product of the refining of copper, lead, zinc, and other metals. In addition, significant quantities of silver are derived as a by-product of gold mining. The top states for mine production are Idaho, Nevada, Montana, Arizona, and Utah. Five smelting and refining companies produce the major portion of domestic primary silver. The smelters and refineries treat ores, concentrates, residues, and precipitates from company mines and plants in addition to materials purchased from other sources. Silver scrap is recycled by several primary smelters and a considerable number of small secondary refineries. In addition, secondary silver is recovered by several trading and fabricating companies and is recycled by end- product manufacturers. In recent years, government regulations relating to the environment and to control of emissions of hazardous compounds have limited the operation of some base metal smelters that recover silver as a by-product. Silver in its ionic form, as in waste discharged from electroplating plants, is considered a potential source of pollution and a health hazard. Because of increasing concerns about environmental matters, governmental agencies can be expected to step up their efforts to minimize discharges from processing plants. The following table presents primary statistics for U.S. silver demand in 1987. A general indication of the annual demand pattern for silver can be drawn from this data: End use Demand, troy ounces × 10 6 Electroplated ware 2.5 Sterling ware 3.8 Jewelry and arts 4.2 Photography 60.2 Dental and medical supplies 1.3 Brazing alloys and solders 5.6 Mirrors 1.0 Batteries 2.5 Contacts and conductors 22.7 Bearings 0.3 Coin, medallions, and commemorative objects 4.2 Catalysts 2.5 Other 4.5 Total U.S. demand 115.3 Several factors can affect the supply and demand of silver. One factor is the appreciable amount of silver required for monetary purposes; another is the speculative or investor market in refined silver bars and sacks of domestic coins. In addition, there has been some interest in the collection of commemorative medallions and limited-use objects fabricated from silver. Whether the latter end use will continue to grow or will decline in the future is a matter of considerable interest. In any event, depending on prices, a large potential secondary supply of silver is available in the form of coins, silverware, jewelry, and commemorative objects. Gold. Because of its aesthetic beauty and enduring physical properties, gold is important not only to industry and the arts, but also as a commodity having long-term value. In the past, gold was considered to be mainly a monetary metal. However, starting in the late 1950s, more gold was used by manufacturers and investors than was used for monetary purposes. Since 1968, gold has become, to a considerable extent, a free-market commodity, with prices free to adjust to supply and demand. Despite this open market, almost half of the total world supply of gold, estimated at 2.4 billion troy ounces, is in various government vaults tied down by agreements among large industrial nations. About 1.7 million troy ounces of gold per year are mined and reclaimed from old scrap in the United States (see, for example, the section "Recycling of Electronic Scrap" in the article "Recycling of Nonferrous Alloys" in this Volume). This amount falls far short of the amount required by U.S. industry. The requirements for bullion and coins are almost equal to those of industry. Because of this general demand for gold, the net inflow of this metal from foreign sources is large. In 1988, for example, 3.0 million troy ounces were imported, mostly in the form of refined metal. About 50% of U.S. refinery production comes from gold ores, and the remainder from by-products of the refining of copper and other base metals. Refinery production in the United States includes gold from domestic mines, from imported ores and base bullion, and from domestic and foreign scrap. In recent years about 5 to 10% of U.S. refinery production has been derived from foreign ores, base bullion, and scrap. About 5 to 10% of the total U.S. supply of gold comes from old scrap, which is defined as metal discarded after use. New scrap, which is generated during manufacturing, is usually reclaimed by the fabricator and is not considered part of the market supply. The United States has appreciable gold resources, some of which are marginally profitable to recover. The price is now high enough to encourage growth of production at a modest rate, but environmental restraints on placer mining and the high cost of developing lode deposits currently dictate that the United States will continue to import most of its gold. The largest foreign producer of gold, the Republic of South Africa, produced about 20 million troy ounces of the estimated 1988 total world production of 59 million troy ounces. Other important gold producers are the Soviet Union, Canada, South America, Asia, and Oceania. According to the U.S. Bureau of Mines, world resources are adequate to meet the forecast demand for this metal to the year 2000. Data for U.S. gold demand in 1988 illustrates the general pattern of consumption of gold in fabricated products: End use Demand troy ounces × 10 3 Jewelry and arts 1774.0 Dental supplies 247.0 Industrial products 1176.0 Total U.S. demand 3197.0 Source: U.S. Bureau of Mines The use of gold for jewelry accounts for approximately 55% of the gold consumed. Dental uses generally amount to 7 to 8% of annual demand. Industrial requirements are generally centered in the electronics industry. However, even though the total number of end uses for gold in electronics continues to be high, considerable emphasis has been placed on reducing the use of gold in present applications because of its increasing cost. Bars, medallions, coins, and related products amounted to less than 1 4 of 1% of the total U.S. gold consumption in 1988. Platinum-Group Metals. The six closely related metals in the platinum group commonly occur together in nature. These transition elements are near neighbors in periods 5 and 6 of group VIII in the periodic table. Ruthenium, rhodium, and palladium each have a density of approximately 12 g/cm 3 , osmium, iridium, and platinum each have a density of about 22 g/cm 3 (see Table 1). The platinum-group metals are among the scarcest of metallic elements, and for this reason their cost is high. They occur as native alloys or in mineral compounds in placer deposits, sometimes together with gold; they also occur in lode deposits in basic or ultrabasic rocks, where they may be found together with nickel and copper. Most of the world supply of platinum-group metals is currently extracted from lode deposits in the Republic of South Africa, the Soviet Union, and Canada. Another major source of platinum-group metals is old scrap obtained from obsolete equipment, spent catalyst, and discarded jewelry. This source is increasing in importance with the broadening industrial applications of these metals. Material of each type can be concentrated by a number of different methods, then refined by any of several chemical processes that conclude with a heating step to convert precipitates to metal in a porous, somewhat powdery form called sponge. Sponge is the most common form in commercial metal transactions, although ingots and shot are also traded. In lode deposits, platinum-group metals are often associated with nickel and copper sulfide, which may be the principal products of mining (as in Canada and the Soviet Union) or important coproducts (as in the Republic of South Africa). In the ores, the proportions of the six platinum-group metals vary from one lode deposit to another. Canadian deposits in the Sudbury District contain approximately equal amounts of platinum and palladium; South African deposits contain more than twice as much platinum as palladium. Generally, platinum and palladium together account for about 80 to 85% of the platinum-group metals present in any given ore, followed by (in order of decreasing presence) ruthenium, rhodium, iridium, and osmium. The composition of placer deposits differs somewhat from that of lode deposits. Placer deposits are characterized by the nearly complete absence of palladium and the common presence of gold. It appears the palladium and, to a certain extent, platinum, rhodium, and ruthenium are dissolved away during placer formation; in the well-established placer deposit in Witwatersrand, South Africa, only osmium and iridium are present (as the alloy osmiridium). At present, the only economically important placers are found in Colombia, South Africa, and the Soviet Union; together they account for about 2% of total world production. The United States depends almost entirely on foreign sources for platinum-group metals. In 1988, net import reliance as a percentage of apparent U.S. consumption was approximately 93%. Apparently U.S. consumption during 1988 is estimated at 2.7 million troy ounces. The sources of U.S supply between 1984 and 1987 were the Republic of South Africa, 44%; the United Kingdom, 16%; the Soviet Union, 9%; all others, 31%. One company in Texas recovers platinum-group metals as by-products of the copper-refining process. In addition, about 24 smaller refineries located mostly on the East and West Coasts, handle or in some way process domestic scrap. However, most of them treat only platinum and palladium, and only three or four refine all six metals. At present, U.S. mine production and reserves of platinum-group metals are small; untapped domestic resources appear to be large but are not well explored. The heavy dependence the United States places on foreign sources for these critical metals has strategic implications as well as a substantial impact on the U.S. balance of payments. The need for exploration and development of U.S. resources is apparent. The U.S. demand for platinum-group metals is projected to grow at an annual rate of about 2.5%, with an estimated 1990 demand of 3.3 million troy ounces. Demand in the rest of the world is forecast to grow more slowly than in the U.S.; it is expected to reach a level of about 9.7 million troy ounces in the year 2000. World reserves and resources appear to be more than adequate to meet this demand. The U.S. demand patterns in 1988 for three of the most-used platinum-group metals were: 1988 Demand, troy ounces × 10 3 End use Platinum Palladium Rhodium Automotive 609,000 160,000 65,000 Chemical 61,976 81,343 3,091 Dental and medical 10,871 227,747 142 Electrical 108,660 386,710 3,508 Glass 19,896 350 2,748 Jewelry and decorative 11,932 7,356 5,254 Petroleum 36,730 26,111 45 Miscellaneous 76,394 135,581 22,787 The United States and Japan currently use about 60% of the platinum-group metals produced. Western Europe and the Soviet Union essentially divide the remaining 40%. Automotive emission requirements (which require the use of a platinum-palladium catalyst) began in 1974 in the United States and presently are substantial (this application alone accounted for 43% of total consumption in 1987). In Japan, about three-fourths of the platinum goes into jewelry, whereas in the United States and Western Europe, about 5 to 15% of this metal is used in jewelry. Substantial increases in the use of platinum-group metals can be expected in the European Economic Community with the gradual implementation of restrictions on automobile emissions from 1988 through 1993. [...]... Soft inlays and medium-hard inlays and crowns 17 83 1.0 10.0 1015 1860 94 596 0 17301760 16.6 Q73 Q80 Q345 Q50 Q103 Q15 Q35 18 77 1.0 14.0 1025 1880 92 596 0 1 695 1760 15 .9 Q92 Q101 Q400 Q58 Q186 Q27 Q38 Hard inlays, crowns, and fixed bridgework 19 74.5 3.5 11.0 1030 1 890 93 096 0 17101760 15.5 Q110/H165 Q121/H182 Q434/H531 Q63/H77 Q207/H276 Q30/H40 Q 39/ H 19 20 66.0 4.0 20.0 1030 1 890 92 595 0 17001740... Dentistry, 198 6 Classification of Dental Alloys A variety of alloys are available for dental applications: • • • • • • • Direct filling alloys Crown and bridge alloys Partial denture alloys Porcelain fused to metal (PFM) alloys Wrought wire alloys Implant alloys Soldering alloys Of these categories, precious metals are used in direct filling alloys, crown and bridge alloys, PFM alloys, and soldering alloys. .. Q120/H165 Q132/H182 Q441/H662 Q64/H96 Q283/H524 Q41/H76 Q38/H17 21 62.0 3.0 25.0 1020 1870 88 095 0 16151740 14.3 Q130/H 190 Q145/H210 Q 490 /H662 Q71/H96 Q 290 /H483 Q42/H70 Q35/H15 22 60.0 4.0 27.0 1020 1870 91 596 5 16751770 14.2 Q103/H175 Q113/H 193 Q407/H 593 Q 59/ H86 Q203/H358 Q 29. 5/H52 Q34/H11 23 58.0 3.5 27.0 1020 1870 91 596 5 16751770 14.0 Q130/H 190 Q143/H210 Q427/H621 Q62/H90 Q 290 /H552 Q42/H80 Q28/H10 24... 1020 1870 890 915 16351675 14.5 Q150/H215 Q165/H237 Q455/H765 Q66/H111 Q 296 /H603 Q43/H87.5 Q35/H4 32 60.0 4.0 22.0 97 0 1780 890 905 16301660 14.1 Q135/H225 Q1 49/ H248 Q483/H883 Q70/H128 Q300/H672 Q43.5/H97.5 Q34/H3 33 56.0 4.0 25.0 98 0 1800 87 093 0 16001710 13.6 Q1 69/ H231 Q186/H254 Q503/H745 Q73/H108 Q372/H720 Q54/H104.5 Q38/H2.5 34 42.0 9. 0 26.0 98 0 1800 84 597 0 15551780 12.6 Q175/H265 Q 193 /H 292 Q586/H883... metal alloys 1 87.5 10.0 1.0 1260 2300 10401140 190 02085 19. 2 150 165 483 70 414 60 5 14.7 2 87.5 4.5 6.0 1.0 1260 2300 11501175 21002150 18.3 165 182 500 72.5 450 65.3 5 14.7 3 86.0 10.0 2.0 1260 2300 10701 190 196 02170 19. 2 170 190 586 85 517 75 5 14.7 4 75.0 18.0 1.0 1300 2372 10851185 199 02165 17.0 210 230 620 90 517 75 5 14.7 5 69. 0 18.5 9. 0 1 290 2350 11651250 21302280 16.7 190 210 662 96 517... 61.0 1120 2050 96 01055 1760 193 0 10.8 Q150/H155 Q165/H170 Q586/H620 Q85/H90 Q241/H448 Q35/H65 Q10/H10  29 25.0 70.0 1175 2150 10201100 18702010 10.6 Q130/H140 Q143/H154 Q434/H4 69 Q63/H68 Q262/H324 Q38/H47 Q10/H8 Extra-hard inlays, thin crowns, fixed bridgework, and partial dentures 30 69. 0 3.0 3.5 12.5 1030 1 890 92 094 5 1 690 1730 15.2 Q135/H240 Q1 49/ H264 Q 490 /H776 Q71/H112.5 Q276/H 493 Q40/H71.5 Q35/H7... 18.5 18.5 1.0 10 63.5 16 .9 19. 5 0.2 11 59. 5 27.6 12.2 0 12 60.0 22.0 13.0 (5.0 In) 13 49. 5 30.0 20.0 (0.5 Pd) 14 41.0 32.5 26.5 0 15 40.0 31.2 28.8 0 Source: Corrosion, Volume 13 of ASM Handbook, formerly 9th Edition of Metals Handbook (a) Numbers are provided for reference purposes only; they are not alloy designations Crown and Bridge Alloys Alloys for all -alloys cast crown and bridge restorations... some typical mechanical properties for a number of different alloy systems used in dentistry Additional information on the compositions, properties, and applications of dental alloys can be found in Ref 9 and 10, and in the article "Tarnish and Corrosion of Dental Alloys" in Corrosion, Volume 13 of ASM Handbook, formerly 9th Edition Metals Handbook References cited in this section 9 R.W Phillips, Skinner's... Mines, 198 3 2 R.G Reese, Jr., Silver, in Mineral Facts and Problems, Bulletin 675, U.S Bureau of Mines, 198 5 3 J.M Lucas, Gold, in Mineral Facts and Problems, Bulletin 675, U.S Bureau of Mines, 198 5 4 Platinum-Group Metals in the Third Quarter 198 8, Miner Ind Surv., 198 8 5 Platinum-Group Metals in the Fourth Quarter 198 8, Miner Ind Surv., 198 8 6 Gold and Silver in June 198 9, Miner Ind Surv., Aug 198 9 7... firing temperatures Compositions and properties of precious metal PFM alloys are given in Tables 6 and 7 Table 7 Compositions of precious metal porcelain fused to metal alloys Alloy(a) Composition, wt% Au Pt Pd Ag Other 1 87.5 4.2 6.7 0 .9 0.3 Fe, 0.4 Sn 2 84.8 7 .9 4.6 1.3 1.3 In, 0.1 Ir 3 54.2 25.4 15.7 4.6 Sn 4 51.4 29. 5 12.1 6.8 In 5 59. 4 36.4 4.0 Ga 6 19. 9 0 .9 39. 0 35 .9 3 Ni, 1.2 Ga 7 60.5 32.0 . copper. Until 196 4 the U.S. coin silver was an alloy of 90 % Ag (90 0 fine) and 10% Cu. Silver bullion that is traded has a silver content ranging from 99 9 fine to 99 9 .9 fine. Gold and copper are. (0.816) (0.4 49) (0. 697 ) (0.378) 17 69 1554 2447 196 3 3045 2310 1064.4 96 1 .9 Melting point, °C (°F) (3216) (28 29) (4437) (3565) (5513) (4 190 ) ( 194 8) 1763.4 Boiling point, °C (°F) 3800 290 0 4500. Third Quarter 198 8, Miner. Ind. Surv., 198 8 5. Platinum-Group Metals in the Fourth Quarter 198 8, Miner. Ind. Surv., 198 8 6. Gold and Silver in June 198 9, Miner. Ind. Surv., Aug 198 9 7. Metal