| 摘要 |
PURPOSE:To obtain a cantilever pipe which has the fast rise of sound and improved acoustic characteristics, by increasing hardness, rigidity, elasticity, etc., by forming a crystalline alumina layer by performing the two-stage anode oxidationof the surface of an Al (alloy) base pipe; CONSTITUTION:One terminal 1a of an Al or Al-alloy pipe base material is sealed by being pressed and a hole 2 for stylus installation is made near the terminal. After this base material 1 is pretreated as required, the same anode oxidation with the ordinary formation of an ''Alumite '' film is performed to form an amorphous alumina layer. With current density high enough to cause plasma discharge on tne alumina layer surface, especially 10-50A/dm<2>, anode oxidation as the 2nd stage is performed in an electrolytic bath of weak acidm for example, 1.5-2.5M/l density Na2CO3, at 30-50 deg.C and for about 2-7min, thus forming an about 10mum crystalline alumina layer 3. Consequently, a cantilever pipe which has large strength, increased internal friction,and superior acoustic and mechanical characteristics is obtained. |
