| 摘要 |
PURPOSE:To uniformly finish the surface quality of the metal to be treated by controlling the concn. of the treating liquid contg. a small amount of HF used for the surface treatment of Al and Al alloys to a prescribed range with the measured value of the F ion concn., pH or conductivity of the liquid. CONSTITUTION:The treating liquid consisting of an aqueous soln. using sulfuric acid as a principal agent and a small amount of hydrofluoric acid as an accelerator is put into a treating liquid tank 1, and Al, Al alloy materials to be treated are immersed into this, whereby they are surface- treated. At this time, the pH of the liquid is measured with a pH detector 2 immersed in the liquid, and the concn. of free F ions is measured with an F ion concn. detector 3. The measured electrode potential 4 of the former is converted to a low impedance by a pH converting amplifier 6 and a pump 16 is operated via a pump operating part 14 by the signal 12 thereof, whereby the sulfuric acid which is the principal agent is replenished at a proper rate. The measured potential 5 of the latter goes through an F ion cocn. converting amplifier 7 then through a controller 11, and a pump 17 is operated in a pump opeating part 15, whereby HF is replenished into the treating tank 1. In this way, the concn. of the treating liquid is maintained always constant; therefore the treatment condition of the surfaces of the Al etc. is maintained always uniform. |
