| 摘要 |
PURPOSE:To regenerate phosphoric acid having excellent ability of rough surface forming treatment and to contrive to effectively utilize phosphoric acid, by adding an Al-containing compound to phosphoric acid used in rough surface forming treatment of the surface of Al-containing ceramic substrate, heating and removing precipitated sediment. CONSTITUTION:Phosphoric acid having >=0.1% dissolved Al used for rough surface forming treatment of the surface of ceramic substrate containing Al such as Al2O3, mullite or AlN is blended with Al or Al-containing compound such as Al metal, Al2O3 or Al(H2PO4)3 containing no metal except Al in such a way that the Al or Al-containing compound is dissolved into preferably 0.6-1.0% Al concentration to raise the Al concentration, the phosphoric acid is heated at 250-500 deg.C for 0.5-3hr to precipitate sediment. Then the phosphoric acid is allowed to cool to about room temperature, water is added to the phosphoric acid into 20-40wt.% condensed phosphoric acid concentration, hydrolysis is carried out at 70-90 deg.C for 1-2hr, the condensed phosphoric acid is decomposed and precipitated sediment is removed by a means such as filtration or centrifuging to give regenerated phosphoric acid.
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