ASTM F7-95(R2021) pdf free download

ASTM F7-95(R2021) pdf free download.Standard Specification for Aluminum Oxide Powder
1. Scope
1.1 This specification covers aluminum oxide (alumina) powder in two classes of particle size, two chemical grades, and two levels of acidity, for use as an insulating coating or as an ingredient ofceramic mixtures for components ofelectronic devices as follows: 1.1.1 Particle Sizes: 1.1.1.1 Class A—Particle size No. 500 nominal mesh (nominal average particle size = 24.3 µm). 1.1.1.2 Class B—Particle size No. 900 nominal mesh (nominal average particle size = 1.7 µm). 1.1.2 Chemical Grades—Grades 1 and 2 as specified under chemical requirements in Section 3. 1.1.3 Acidity Levels: pH (acid) 4.5 to 6.5 and pH (neutral) 6.5 to 7.5. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 The following safety hazards caveat pertains only to the test methods in this specification. This standard does not purport to address all ofthe safety concerns, ifany, associated with its use. It is the responsibility ofthe user ofthis standard to establish appropriate safety, health, and environmental practices and determine the applicability ofregulatory limita- tions prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Chemical Composition
3.1 For a specified particle size and level of acidity, the aluminum oxide shall conform to the requirements of Table 1 as to chemical composition.
4. Physical Properties
4.1 The alumina shall be “chalk white,” dry, free from lumps, and of particle size distribution as agreed upon between purchaser and seller.
5. Sampling
5.1 Each lot of alumina shall be properly sampled in accordance with standard techniques, such as Practice C183. 6. Test Methods 6.1 Water-Soluble Content: 6.1.1 Procedure—Determine the total water-soluble content by measuring the electrical conductivity of a 100-mL distilled or deionized water extract from a 5-g sample of alumina. Elutriate by vigorously shaking the alumina suspension in a flask for 1 to 2 min, allowing the solids to settle and decanting the clear supernatant liquid after 60 min. Measure the conduc- tivity of the liquid with a standard cell and bridge. Correct this measurement for the “blank” reading on a similarly treated equal volume of the same pure water. Convert the net increase in conductivity of the water extract first to parts of water- soluble content as sodium chloride (NaCl) per million parts of water (factor is 1 micromho = 0.5 ppm NaCl), then relate to the actual weight of elutriated alumina. For example, on a typical 100-mL extract 10 micromhos (net) or 5 parts of NaCl per million of water in this volume of liquid is equivalent to 100 parts of NaCl per million of alumina on the basis of a 5-g sample.6.2.4 Particle size distribution ofacceptable material in both Class A and Class B will be by agreement between purchaser and seller. Sample size and method of dispersion will be identical in all test correlations, as specified in Table 2. Typical results are shown in Table 3. 6.2.5 Number average particle size ofacceptable material in both Class A and Class B will be by agreement between purchaser and seller. 6.2.6 Complete dispersion of samples is essential and rec- ommended procedure in Table 2 shall be followed. 6.3 Hydrogen-Ion Concentration (pH): 6.3.1 Weigh out 20 g of the sample and transfer to a clean 100-mL beaker. Add 20 mL of distilled or deionized water and make into a slurry using a clean stirring rod. Stir for 1 to 2 min. Wash electrodes thoroughly with distilled or deionized water, remix slurry, immerse electrodes into slurry approximately 6 to 12 mm, and measure pH in accordance with Test Method E70. 6.3.2 Any weight of slurry in the above ratio may be used provided there is sufficient slurry to immerse electrodes to the proper depth. 6.3.3 Wash electrodes immediately after using with several hundred millilitres ofdistilled or deionized water, removing the adhered slurry with the aid of a pipe cleaner. It is important for accuracy to prevent buildup of the slurry on the electrodes.