Значение и использование

Many of the low-silica technical glasses which contain soluble or reactive oxides require processing or involve applications that require cleaning. Very often these cleaning procedures have evolved over several decades and are considered an art. They usually contain numerous steps, some of questionable validity. It is the premise of this practice that cleaning glass can be more scientific. Design of a cleaning procedure should involve (1) a definition of the soil to be removed, (2) an awareness of the constraints imposed by the glass composition, and (3) a rational selection of alternative methods that will remove the soil and leave the glass in a condition suitable for its intended application. This practice provides information to assist in step (3). General references on glass cleaning and on various methods of evaluating cleanliness and associated information has been published.

Область применения

1.1 This practice covers information that will permit design of a rational cleaning procedure that can be used with a glass that is somewhat soluble in many aqueous chemical solutions. Typically, this type of glass is used in applications such as optical ware, glass-to-metal seals, low dielectric loss products, glass fibers, infrared transmitting products, and products resistant to metallic vapors.

1.2 In most cases, this type of glass contains high concentrations of oxides that tend to react with a number of aqueous chemicals. Such oxides include B₂O₃, Al₂O₃, R₂O, RO, La₂O₃, ZnO, PbO, P₂O₅, and Fe₂O₃. The more conventional high-silica glasses are usually more chemically resistant, but the cleaning principles outlined here also apply to them.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 4 and Table 1.

TABLE 1 Relative Solubility of Various Glass Component Oxides in HF, Other Inorganic Acids, and NaOH, in Concentrated Solutions at Room Temperature

Note 1—Macro or minor/trace levels will determine degree of precipitation, especially in acids, for example, HNO₃ (Sn, Sb, Mo).

Note 2—W is soluble in acid but heat may precipitate it, for example, H₂WO₄.

Note 3—Sn⁺⁴ is soluble in hot H₂SO₄; Sn⁺² is soluble in other reagents as well.

Note 4—Most alkali solutions must be hot to effect solution.

Note 5—PbSO₄ is soluble in hot concentrated H₂SO₄.

Note 6—Sb and Bi form insoluble oxychlorides in dilute HCl.

Note 7—Ba is insoluble in concentrated HNO₃.

Oxides ofHF
49 %H₂SO₄
96 %HNO₃
70 %HCl
37 %HBrHIH₃PO₄
85 %NaOH
50 % Al s^Asssiiis Sb i^Aiisssis Asssssssss Baiissssss Besssssssi Bisssssssi Bssssssss Cdssssssss Caisssssss Ceisiiiiii Criiiiiiii Cosssssssi Cusssssssi Erissssssi Euissssssi Gdissssssi Gasssssssi Gessssssss Auiiiiiiii Hfsiiiiiii Fesssssssi Laissssssi Pbiisiiiss Lissssssss Mgissssssi Mnsssssssi Moss i^Bsssss Ndissssssi Nisssssssi Nbsiiiiiii Pdssiiiiii Pssssssss Ptiiiiiiii Kssssssss Prissssssi Pmissssssi Rhissssssi Rbissssssi Ruissssssi Smissssssi Sessssssss Sisiiiiiis Agsssiiisi Nassssssss Sriiiiiiii Tasiiiiiii Tessssssss Tlssssiisi Ths s^Biiiiii Snssssssss Tis s^Bisiiii Wsiiiiiis Usssiiiii Vssssssss Ybissssssi Yissssssi Znssssssss Zrs s^Biiiiii

^A s = relatively soluble, i = relatively insoluble.

^B hot