(華北水利水電大學(xué) 機(jī)械學(xué)院，鄭州450045)
摘 要: 為了揭示AgCuZnSn釬料的熱力學(xué)特性，以BAg50CuZn釬料為原材料，采用熔煉合金化方法制備高錫AgCuZnSn釬料。借助差示掃描量熱儀(DSC)測定不同Sn含量AgCuZnSn釬料的熔化溫度，運(yùn)用熱分析動力學(xué)中的非等溫微分法和積分法分析AgCuZnSn釬料的相變熱力學(xué)特性。利用熱力學(xué)熵的概念，提出AgCuZnSn釬料釬焊工藝熵和接頭性能熵的數(shù)學(xué)表達(dá)式。結(jié)果表明：隨著Sn含量升高，AgCuZnSn釬料的吸熱峰向左偏移，且在吸熱峰釬料相變溫度區(qū)間變窄。非等溫微分法和積分法得到的AgCuZnSn釬料的相變活化能隨著Sn含量增加逐漸增大；當(dāng)Sn含量相同時(shí)，兩種方法得到的釬料相變活化能幾乎相同。當(dāng)Sn含量為7.2%(質(zhì)量分?jǐn)?shù))時(shí)，AgCuZnSn釬料的相變活化能和指前因子值最大，分別為364.46 kJ/mol和7.29×1020。試驗(yàn)結(jié)果證實(shí)了釬焊工藝熵和接頭性能熵的表達(dá)式在一定程度上可定量表征AgCuZnSn釬料的釬焊性能。
關(guān)鍵字: 銀釬料；熔化特性；熱力學(xué)熵；活化能
（School of Mechanical Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, China）
Abstract:By revealing the thermodynamic properties of AgCuZnSn brazing alloys, brazing alloys of high Sn content were prepared using melting alloyed method based on BAg50CuZn substrate. The melting temperature of brazing alloys was observed by differential scanning calorimeter (DSC), and its phase transformation thermodynamic characteristic was analyzed with the thermal analysis kinetics of non-isothermal differential and integral methods. The mathematical expression of process entropy and performance entropy of brazing alloys were proposed. The results show that the DSC endothermic peak of AgCuZnSn brazing alloys shifts to the left, and its phase transformation temperature interval would be narrower with the increase of Sn content. The phase transition activation energy of AgCuZnSn brazing alloys gradually increases using non-isothermal methods. Under the same Sn content, the phase transition activation energy of brazing alloys with non-isothermal differential method is exactly the same as that of integral method. When Sn content is 7.2% (mass fraction), the transition activation energy and pre-exponential factor of brazing alloys reach the maximum, which are 364.46 kJ/mol and 7.29×1020, respectively. The results indicate that the expression of process entropy and performance entropy could quantitative analyze the brazability of AgCuZnSn brazing alloys.
Key words: silver brazing alloy; melting characteristic; thermodynamic entropy; activation energy
