Papers by Keyword: Laser Cladding Coating

Abstract: Depth of evaluation method of surface crack in laser cladding coating with metal magnetic memory was introduced in this paper. Laser cladding coating specimen were degaussed, placement direction of specimen and detection direction unchanged, detection speed and lift off value of probe were the constant. Results show that gradient value of H_p(y) signal corresponding to surface crack increases as tensile load increases under the same depth of surface crack, gradient value of H_p(y) signal corresponding to surface crack increases as depth of surface crack increases under the same tensile load. Orientation of internal magnetic domain changes as tensile load changes and magnetic leakage field caused by surface crack are seen as two main reasons for above results. Using fitting method with quadratic polynomial, depth of surface crack in laser cladding coating can be evaluated nondestructively in this paper.

Abstract: The thickness of thin laser cladding coating is evaluated with surface ultrasonic wave based on denoising with wavelet analysis method. Two surface ultrasonic wave transducers with 5MHz frequency, which are employed as a transmitter and a receiver, are employed to detect surface ultrasonic wave signals, and cross correlation function is used to determine the difference in time between signals. Results show that the velocity of surface ultrasonic wave propagating in laser cladding Fe314 alloy coating decreases as the thickness of coating increasing, the microstructure of coating is the main reason for noise, the signal-to-noise ratio increases after denoising with db4 wavelet, the result of coating thickness and the difference in time is fitted with polynomial, and the fitting formulas are obtained responding to initial signal and denoising signal, respectively. Based on metallographic analysis result, this method is considered to be evaluated the thickness of thin laser cladding Fe314 alloy coating and the accuracy can be improved based on denoising with db4 wavelet.

Abstract: AISI 1045 steels were laser-clad with Ni-based powder by CO2 HJ-4 coherent laser. The phase composition of the laser-cladding coating was investigated by means of X-ray diffraction (XRD). The cross-section of the cladding coating was observed using a scanning electron microscopy (SEM). The friction and wear properties of the laser cladding coatings sliding against AISI 52100 steel under the lubrication of liquid paraffin containing various anti-wear and extreme pressure additives were investigated using an Optimol SRV reciprocating motion friction and wear tester. Results showed that the laser-cladding coating considerably decreased coefficient of friction and increased wear resistance in sliding against AISI 52100 steel and attributed to the change in the hardness, phase composition of the laser-cladding coating and tribochemical reactions between the laser-cladding coating and the extreme pressure and anti-wear additives.

Abstract: Laser cladding Fe-based alloy coatings with 0, 3, 6, 9, 12 and 15% Al2O3 xerogel on 45 steel substrates were prepared by 5kWCO2 continuous wave laser. The effect of the content of Al2O3 xerogel on the microstructure, microhardness and wear resistance of the coatings was investigated by scan electron microscope, X-ray diffraction. The results show that the microstructure and properties were different when the content of Al2O3 xerogel changed. The addition of Al2O3 xerogel can enhance the fluidity of molten liquid and refine the microstructure. Adding adequate amount of Al2O3 xerogel to Fe-based alloy can improve the hardness and the wear resistance due to the nano-Al2O3 particles on surfaces and the dispersion strengthening and hardening of nano- Al2O3 particles.