Investigation On In-situ TiC/FeAl Coating Prepared With Ultrasonic Vibration Aided Laser Cladding Technology

For the traditional component made from metallic material, wear failure seriously decreases its working life. As a result, it is a processing technology of bright future to add wear-resistant coating of intermetallic compound on the surface of metallic material with laser cladding. In this work, ultrasonic vibration aided laser cladding technology was adopted to prepare the composite coating, and the action mechanism of ultrasonic vibration on the coating was investigated, which was of great theoretical significance.Firstly based on the physical parameters of Fe-Al-C-Ti melt, the cavitation and acoustic steam of the ultrasonic vibration in the melt were calculated. Also the possibility of generating resonance effect with ultrasonic vibration in melt was analyzed. The results showed that higher sound pressure leads to larger cavitation; the generation of cavitation is determined by the radius of tiny bubbles and the amplitude of sound pressure, and when the bubble ruptures, sound pressure in the level of 105 Pa will generate temperature in the level of 104 ℃ and pressure in the level of 1010 Pa. And it was observed that the highest sound pressure generated by the acoustic steam in this work can reach to 107 Pa, the sound pressure decreases along with the increasing of normal and horizontal distances, and the ampitude transformer with amplitude of 10 um can generate equivalent acoustic steam force of 1.5m/s2.By the use of ultrasonic vibration aided laser cladding technology, the TiC/FeAl coating in-situ was prepared on the surface of 45 steel. With metallographic microscope, X-ray diffractometer, SEM, investigation on the micro-organization and the phase composition of the coating was performed. The wear coefficient and wear resistance of the coating were also researched via friction and wear testing equipment and microhardness tester. The results showed that ultrasonic vibration aided laser cladding technology is able to prepare Tic/FeAl coating, and the cavitation of ultrasonic vibration can actuate the reaction in-situ in the coating. Also it was observed in the investigation of micro-organization that the dilution rate of the coating increases and the crystal particle is obviously refined after adding ultrasonic vibration; and ultrasonic vibration transforms the distribution of TiC reinforcing phase from agglomerate state to uniform state in the coating. By using the laser with power of 2000 W and the ultrasonic with frequency of 20.0kHz, the crystal particle in the coating prepared is the smallest. Additionally the coating prepared with overlap ratio of 40% shows the best performance, which means the crystal particle is very small, TiC reinforcing phase is distributed uniformly and there is no cracks and holes. In the investigation, it was shown that the wear resistance of the coating increases two times while the average friction coefficient deduces by 73% after adding ultrasonic vibration; with using ultrasonic vibration, when the laser power and vibration frequency increase, the wear resistance increases at first and then decreases, and the average friction coefficient shows the same trend along with the increase of the vibration frequency; the wear mechanism of the coating is changed from adhesive wear to the coupling of adhesive wear and abrasive wear after adding ultrasonic vibration; the micro hardness of the coating after adding ultrasonic vibration is enhanced by 39%.