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目前,透射电镜薄膜样品的制备方法,大多采用双喷电解抛光作为最终的减薄方法,抛光电源采用一般的稳压直流电源,样品被减薄至穿孔,在孔的周围获得电子能够穿透的“透明”薄区。众所周知,制备电镜样品的成败除了与电解液和抛光条件的选择有关,对样品穿孔的控制是很关键的。利用稳压直流电源制作样品,速度较快,但样品在穿孔时不易控制。到目前为止,用于控制穿孔的多种自控方法(如光电管、光电控制器)都存在不足之处。为此,作者从保护薄区入手,采用恒流直流电源代替一般稳压直流电源制作电镜样品,对Ni-Al、Fe-Ni、纯Fe、45号钢等样品进行双喷减薄,取得显著效果,制备样品成功率(在双喷前的各工序良好操作条件下)几乎达到百分之百。对同一材料,在同样电解液与抛光条件下,分别使用恒流与稳压电源进行了对比实验,结果表明,恒流源抛光的样品穿孔较小,从而薄区较大。用恒流源保护薄区的思想是独特的,它不同于以前只用控制穿孔速度的办法来增加“透明”薄区,而利用恒流源自身的特性,在穿孔时自动减少抛光功率,以保护“透明”薄区,其原因可能是:利用恒流源抛光功率、电流和电阻存在着一定的关系,P=I~2R。因为在穿孔时电解液的电阻降低,而电流值不变,这样使穿孔时的抛光功率降低,穿孔很小,因而可以得到大面积的电子透明的薄区;利用稳压源,抛光功率,电压和电阻存在着一定关系,P=U~2/R,穿孔时电解液的电阻降低,而电压值不变,这样使穿孔时的抛光功率升高,穿孔较大,有用的“透明”区被腐蚀掉了。综上所述,采用恒流直流源代替稳压直流源制作电镜样品,不失为一种有效和方便的方法。
At present, the preparation methods of TEM film samples mostly adopt double-jet electrolytic polishing as the final thinning method. The polish power source adopts the normal regulated DC power source, the sample is thinned to perforation, and the electron can penetrate around the hole “Transparent” thin area. As we all know, the success of the preparation of electron microscopy samples in addition to the selection of electrolyte and polishing conditions related to the control of the sample perforation is critical. The use of regulated DC power supply samples, faster, but the sample is not easy to control when piercing. So far, a variety of self-control methods used to control perforation (such as photocell, photoelectric controller) are deficiencies. To this end, the author started with the protection of thin areas, the use of constant current DC power supply instead of the general DC power supply produced electron microscopy samples of Ni-Al, Fe-Ni, pure Fe, 45 steel and other samples double spray thinning achieved remarkable The results show that the success rate of preparation samples (under good operating conditions in each process before double-jetting) is almost 100%. The same material, under the same electrolyte and polishing conditions, were compared using a constant current and regulated power supply, the results show that the constant current source polished sample smaller perforation, thin area larger. The idea of using a constant current source to protect the thin-film region is unique. It differs from previous methods of simply increasing the thickness of a “transparent” region by controlling the speed of the perforation. By utilizing the characteristics of the constant current source itself, the polishing power is automatically reduced when piercing The reasons for the protection of “transparent” thin areas may be: the use of constant current source polishing power, current and resistance there is a certain relationship, P = I ~ 2R. Because when the perforation electrolyte resistance decreases, while the current value unchanged, so that the perforation of the polishing power is reduced, the perforation is small, so you can get a large area of electron transparent thin area; using the regulator source, polishing power, voltage And the resistance there is a certain relationship, P = U ~ 2 / R, when the perforation electrolyte resistance decreases, while the voltage value of the same, so that when the perforation of the polishing power, perforation, useful “transparent” area Corroded away. In summary, the use of constant current DC source instead of regulated DC source electron microscopy samples, after all, an effective and convenient method.