| 摘要 |
The work-pieces are mechanically cleaned, degreased and washed, and then etched in an aqueous solution containing 0.5-1.0% by weight of citric acid, and 16-24% by weight of hydrochloric acid, having a temperature of 15 DEG -30 DEG C., preferably of 20 DEG -25 DEG C., for the time of 1-20 minutes, preferably 2-5 minutes, whereafter the work-pieces are neutralized in an aqueous ammonia solution having a concentration not exceeding 1% by weight, at a temperature of 15 DEG -25 DEG C., in a time not shorter than 1 minute. After being washed in water at a temperature not exceeding 35 DEG C. in a time not shorter than 1 minute, they are dipped in an agitated aqueous solution of the flux, containing 1.8-2.5% by weight of potassium fluoride, 0.8-1.5% by weight of sodium fluoride, and 1.5-3.0% by weight of potassium fluorozirconate, having a temperature of 40 DEG -80 DEG C. After at least two minutes of holding in the flux, the work-pieces are dried and finally dipped in a melt of aluminum or alloys thereof. Alternatively a flux having composition 1.5-2.0% by weight of potassium fluoride, 1.5-2.0% by weight of sodium fluoride, 6.0-10.0% by weight of sodium tetraborate and 2.5-5.0% by weight of acetic acid, having a temperature of 15 DEG -40 DEG C. may be used, for a period not shorter than 2 minutes. |
