纯银光亮退火工艺优化

Optimization of Bright Annealing Process of Pure Silver

光亮纯银首饰坯件在中间退火时常出现哑光,增加后续抛光工作量。以首饰行业常用纯银为原料,研究了光亮银条在大气下的退火工艺。结果表明,随着退火时间延长,硬度快速降低并逐渐趋缓;色差不断加大,且呈现先快后慢的趋势。随着加热温度提高,硬度降低速度加快,且最终的硬度值低,而色差值相应增加。因此,光亮纯银在大气下退火时,硬度下降和颜色保持需做出适当的平衡。对于中等壁厚手镯用光亮银条,退火时将温度控制在400℃左右,保温时间约为60 min,可满足硬度降低和光亮度保持需要。

Matte often occurrs in bright pure silver jewelry blank during the middle annealing, which increases the subsequent polishing workload. Taking sterling silver commonly used in jewelry industry as raw material, the annealing process of bright silver bars was analyzed in the atmosphere. The results indicate that with the extension of annealing time, the hardness is decreased rapidly at first and gradually tends to be stable. The chromatic aberration is constantly increased, presenting the pattern of “fast followed by slow”. With the increase of heating temperature, the decreasing rate of hardness is raised, and the final hardness value is low, while the chromatic aberration is increased correspondingly. Therefore, a proper balance needs to be kept between hardness loss and color retention of bright pure silver annealed in the atmosphere. For bright silver bars for bangles with medium thickness, the annealing temperature is controlled at 400 ℃ for about 60 min, which can basically meet the needs of hardness reduction and brightness retention.