深冷处理对口腔中熔铸造合金拉伸力学性能影响的实验研究

The Effect of Cryotreat on the Tension Properties and the Mechanism of the Medium Melting-point Castable Alloy

为把深冷技术引入口腔修复领域,作者把15个SDA Ⅱ型Cu Zn Ni中熔铸造合金试件分为对照组、深冷处理组、(以3℃/min的降温速度降至-170℃,保持2h后以1℃/min的速度升至室温)深冷处理加回火组(深冷处理后,恒温300℃,保持1h),每组取一个作扫描电镜(SEM)观察,其余加工成拉伸试件用应变片测试技术测定其弹性模量、在电子万能试验机上拉断,测试其抗拉强度、最后用游标卡尺测量其延伸率.结果发现SDA Ⅱ型中熔铸造合金经深冷处理后材料强度显著提高(P<0.01),延伸率下降明显(P<0.05),SEM图中出现大量Cu Zn金属间化合物作为第二相析出,十分细小.经回火处理,材料强度进一步显著提高(P<0.01),第二相分布趋于均匀,延伸率恢复到深冷处理前的水平,三组材料弹性模量无显著性差异(P>005).可见深冷处理加回火处理对SDA Ⅱ型中熔铸造合金的拉伸力学性能的改善是必要的,SEM分析支持拉伸试验结果.深冷处理技术有可能成为改善口腔修复材料综合性能的一条简便、有效的途径.

In order to introduce cryotreat technique into prosthetic dentistry, 15 SDA-Ⅱmedium melting-point castable alloy were divided into 3 groups i.e. control group (G1), cryotreat group (G2, in this group the temperature was controlled in 3℃/min cool to 170℃, after keep this temperature 2 hours the temperature was controlled up to room temperature in the speed of 1℃/min) and cryotreated plus post-cryogenic treat group (G3, in this group the specimen were first treated as G2, then toke the specimen into the CS101-A electronic hot-dry wind box heat the specimen to 300℃ and keep an hour ). The gauge test technique was employed to test the modulus of elasticity, then the strength and percentage elongation(PE) were tested. To each group a specimen was observe by the scanning electron microscope(SEM) to study the changes of the SEM image of the alloys. The results show that for SDA-Ⅱmedium melting-point castable alloy, cryotreat and post-cryogenic effectively improved its strength(see tab.1,P<0.01), the PE of G2 decrease 34.0% than G1,after post-cryogenic the PE have no obviously difference between G3 and G1. The modulus of elasticity have not effectively difference among each group. SEM images show that a lot of micro-second phases separate out in β phase in group G2 and G3, in group G3 the second phase separate more uniform than G2. All the results obtained above suggest that cryotreat is a effective method in enhance tension properties of SDA-Ⅱmedium melting-point castable alloy, the post-cryogenic is necessary.