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采用磁控溅射法在生物医用NiTi合金基体表面制备了Ti/CN_x（x≈0.26）梯度薄膜，并制备了Ti/类金刚石(DLC)以及Ti/TiN薄膜进行对比研究. 利用显微硬度计、划痕仪比较分析了上述各薄膜的力学性能，通过表面接触角法研究了薄膜的亲水性. 着重测试并分析了溶血率和血小板粘附行为，进而对薄膜的血液相容性进行评估. 结果表明：Ti/CN_x梯度薄膜与NiTi合金基底的结合牢固，结合力达到63.6N. Ti/CN_x薄膜硬度为23.01GPa，和Ti/TiN薄膜硬度相当，略高于Ti/DLC薄膜. 溶血率和血小板粘附试验表明，Ti/CN_x梯度薄膜能有效改善NiTi合金基底的亲水性和血液相容性，与Ti/TiN和Ti/DLC薄膜相比，Ti/CN_x梯度薄膜具有最小的溶血率，仅为1.12％，并且无论在血小板的粘附数量还是在血小板变形程度都最少，因此具有良好的血液相容性.

Ti/CN_x (x≈0.26), as well as Ti/DLC (Diamond-Like Carbon) and Ti/TiN gradient films were deposited on NiTi alloy substrates using DC (direct current) magnetron sputtering method. The mechanical properties concerning hardness and cohesion of the above three films were tested by using microhardness tester and scratch tester, respectively. The surface hydrophilicities of the three films were measured using contact angle measurement. The blood compatibilities of the substrate and the films were evaluated by hemolysis test and platelet adhesion test. The results indicate that the cohesion between Ti/CN_x film and NiTi alloy substrate is excellent (63.6N). The hardness of the CN_x film (23.01GPa) is nearly equal to that of the TiN film, which is somewhat higher than that of the DLC films. The results of surface hydrophilicity test and platelet adhesion test demonstrate that the hydrophilicity and blood compatibility of NiTi alloy are improved effectively by the modification with the Ti/CN_x film. In comparison with Ti/TiN and Ti/DLC gradient films, Ti/CN_x film has the minimum hemolysis ratio of 1.12%. Among the above gradient films, the Ti/CN_x film has the best blood compatibilities, as indicated by the minimum amount of conglutinated platelets and the least deformation.