Study of Microstructure and Properties of Laser Cladding Ni60-WC + TiC Composite Coating

As a novel surface strengthen technology laser cladding was widely used in surface engineering. In this work, Ni60 + 25%WC + 10%TiC composite coatings were fabricated on the TC4 by laser cladding technology. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and frictional wear were used in the study of coatings. The results showed that dendrites is the main crystal type in the coatings, there were some bulk type crystal generated in 400 mm/min scanning speed. XRD results showed that some of the metalloceramics phases, such as TiC, VC, WC were formed in the coatings, some of the intermetallic compounds such as AlNi3, Al0.96B0.04Ni3, NiTi and C0.12Fe1.88 also formed, which improving the hardness, and the hardness tests results showed that the hardness of the coatings increased by 300% compared to the substrate, of above 1100 HV0.3. The max friction coefficient in 600 mm/min was 0.39, because of the unmelted TiC and WC particles fallen off from coatings, so the mechanism of the coating was abrasive wear. The friction coefficient is decreased to 0.11 and 0.19 when the scanning speed is 500 mm/min and 400 mm/min, respectively.

The Application of Fractal Theory in EDM Surface Strengthening TC4 Titanium Alloy

EDM Surface Strengthening TC4 titanium alloy is a kind of very effective surface strengthen method, and its development prospect is very considerable. The medium in the discharge process has characteristic of self-similarity, which can be well described by fractals. And the discharge channels are an important factor affecting the distribution of discharge energy. The discharge process in kerosene and mixed powder dry medium have been simulated by using fractal theory. And the actual strengthening experiment was conducted in two different medium. The results prove that trajectory characteristics based on fractal theory are basically in agreement with the experiment result of EDM Surface Strengthening TC4 titanium alloy. The fractal theory can guide the EDM surface strengthening research of TC4 titanium alloy.

Brush Plating Surface Strengthen of the Cr12MoV Stamping Die

Cr12MoV are grandly utilized in the stamping die for stainless steel processing, the sticking friction will exist between the die and the stainless steel plate, which will seriously influence the quality of the product and the life of the die. In this paper, brush plating was utilized to plant a Ni-P layer on the surface of the die. The results show that the Ni-P layer could effectively stick to the surface of the Cr12MoV stamping die and also have good rigidity and abrasion-resistance after a heat treatment in 400°C.