ASTM D718-86(R2020) pdf free download

ASTM D718-86(R2020) pdf free download.Standard Test Methods for Analysis of Aluminum Silicate Pigment
8. Procedure
8.1 If an appreciable residue remains after the treatment with HF in accordance with 7.4 ofTest Methods D717, fuse the residue with a small amount of K 2 S 2 O 7 until it is dissolved. Leach the pyrosulfate melt out of the crucible with water and combine the solution with the filtrate reserved in accordance with 7.3 or Test Methods D717. 8.2 Bring the volume of the combined solution to 250 mL, and, if necessary, add HCl in order to ensure a total of 10 to 15 mL of HCl, add a few drops of methyl red indicator solution, and heat to boiling. Add concentrated NH 4 OH (sp gr 0.90) dropwise until 1 drop changes the color of the solution to a distinct yellow. Reheat the solution containing the precipitated hydroxides to boiling, boil for 1 or 2 min, and filter. Wash the precipitate once by decantation and then slightly on the filter with hot NH 4 Cl. 8.3 Transfer the precipitate and paper to the original beaker in which the precipitation was made. Dissolve the precipitate in hot HCl (1+3), dilute to 100 mL, and precipitate again as described in 8.2. After filtering, wash the precipitate ten times with small portions of hot NH 4 Cl solution. Transfer the precipitate to a weighed platinum crucible, heat slowly until the paper is charred, and finally ignite to constant weight at 1050 to 1100°C in an electric furnace or over a burner, taking care to avoid reduction. Weigh the precipitate as Al 2 O 3 + TiO 2 + Fe 2 O 3 . 8.4 Fuse the combined oxides from 8.3 with 9 to 10 g of K 2 S 2 O 7 in a platinum crucible, starting at low temperature and increasing the heat gradually until the oxides have all dis- solved. Take up the melt with 5 mL of H 2 SO 4 (1+1) in 150 mL of water and warm to effect solution. Transfer the solution to a 250-mL volumetric flask, dilute to volume, and mix well. Reserve for TiO 2 and Fe 2 O 3 determinations.8.5 Determine the percent of TiO 2 as follows: Pipet an aliquot containing 0.2 to 3.0 mg of TiO 2 into a 100-mL volumetric flask. For samples containing 0.5 to 3 % TiO 2 , a 20-mL aliquot is suitable. Add 5 mL of H 2 O 2 (3 %), dilute to volume with H 2 SO 4 (1+9) and mix well. Obtain the colorimet- ric reading in a suitable colorimeter using a filter with transmission limits of400 to 450 nm or at 410 nm with a prism or grating spectrometer. Compare the readings to a curve plotted from a set of TiO 2 standards similarly treated and read on the same instrument. 8.6 Determine the percent of Fe 2 O 3 as follows: Pipet a 25-mL aliquot into a 100-mL volumetric flask. Add the following in the order given, mixing well after each addition: 2 mL of NH 2 OH · HCl (10 %), 10 mL of NH 4 C 2 H 3 O 2 (20 %), and 10 mL of o-phenanthroline (0.1 %). Roll a small piece of congo red paper into a ball and introduce into the flask. Add concentrated NH 4 OH dropwise until indicator turns red and 1 drop in excess. Dilute to volume and let stand for 10 to 20 min. Obtain the colorimetric reading in a suitable colorimeter using a filter with transmission limits 485 to 550 nm, or at 510 nm with a prism or grating spectrometer. Compare the readings to a curve plotted from a set of Fe 2 O 3 standards similarly treated and read on the same instrument.8.7 Alternatively the Fe 2 O 3 may be determined by titration as follows: Fuse 1 g of sample with 10 g of K 2 S 2 O 7 in a high-silica crucible starting at low temperature and increasing the heat gradually until the crucible glows with a dull red color and decomposition is judged to be complete. Leach the melt with 10 mL ofconcentrated HCl in 100 mL ofwater and digest at low heat to disintegrate the cake. Filter and wash free of chlorides with hot water. Save filtrate. Ignite the insoluble residue in a platinum crucible. Treat with 5 mL ofH 2 SO 4 (1+1) and 15 mL of HF (48 %), and heat until fumes of H 2 SO 4 appear. Bring the residue into solution with the addition of a few drops more of H 2 SO 4 (1+1) and combine the solution with the bulk of the iron. Add 5 mL of HCl to the combined solutions and evaporate to 50-mL volume.