化学复合镀Ni-P-金刚石旋转弯曲疲劳性能的研究

为研究Ni-P镀及Ni-P-金刚石化学复合镀对40Cr钢疲劳性能的影响,采用成组对比法进行旋转弯曲疲劳试验,并用SEM对疲劳断口进行对比分析.结果表明:与40Cr基底相比,Ni-P镀件及Ni-P-金刚石镀件的疲劳寿命显著降低,经热处理后寿命进一步降低.镀态时Ni-P-金刚石镀件比Ni-P镀件寿命相对较长,而热处理后Ni-P镀件寿命略长.与基底相比,Ni-P-金刚石镀件主要是由于裂纹扩展区寿命降低,而经热处理后的Ni-P-金刚石镀件主要是裂纹萌生阶段寿命降低.综合试验结果得到:镀件的疲劳寿命主要取决于3个因素,一是镀层自身的脆性;二是镀层与基底间的结合;三是施镀过程中的吸氢.

Study on the Properties of Rotating Bending Fatigue of Electroless Ni-P-diamond Composite Coating

To study the influence of electroless nickel-phosphorus deposition or electroless nickel-phosphorus-diamond deposition on the fatigue property of 40Cr, the rotating bending fatigue experiments were finished by group comparative method, and the break morphology was observed by SEM. Results show that the fatigue life of samples with Ni-P coating or Ni-P-diamond composite plating is reduced comparing with 40Cr matrix material, and the fatigue life of rotating bending decreases more after heat-treatment. The fatigue life of samples with Ni-P-diamond composite plating is longer than that of samples with Ni-P plating, but the life of Ni-P plating sample becomes little longer than that of Ni-P-diamond composite plating samples after heat-treatment. The decline of fatigue life of specimens deposited is contributed to the decline of crack extending life, while the decline of fatigue life of specimens after heat-treatment is contributed to the decline of crack initiation life. The fatigue life of specimens with electroless coatings depends on three factors: the brittleness of the coating, the binding force between the coating and the matrix, and hydrogen-adsorption of matrix during the deposition process.