New Hardfacing Material And Its Properties

In this paper, specific to the piston ring which is used on the condition that high temperature, high pressure, high-speed and high-load in modern new-type high-power diesel engine, there is a serious wear and short service life, and so prominent problems. A new high temperature surface wear-resistant chromium carbide/Ni3Al composite was designed and fabricated. Because of good high temperature oxidation resistance of chromium carbide, chromium carbide particles reinforce Ni3Al matrix composite would possess excellent wear-resistance.Apply the hardness tester, optical microscope, scanning electric mirror, energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and other test equipment, to the performance of the testing sample that make to have progress analysis test. The results show that, the excellent metallurgy bonding was formed by the formation of partially melted zone between the coating and the substrate. The hardfacing layer of Ni3Al strengthened by Cr3C2 was formed against the direction of heat flow which showed adnate growing style with base metal; The matrix of Ni3Al could protect and hold-up the Cr3C2, and the matrix of Ni3Al is protected and the hardness of hardfacing layer increased significantly because of the dispersed distribution of Cr3C2 which have high hardness and good wear-resistance; The improvement of the wear-resistance in the whole component due to good metallurgical combination of hardfacing layer and base metal, crack-free, so the hardfacing alloy layer can not exfoliate easily, improves the wear-resistance.The wear resistance of the surfacing layer was tested by Pin-on-Disc friction wear testing machine under unlubricated condition. The friction surface morphology was observed by means of scanning electron microscopy, the friction coefficient and wear rate were tested and the wear mechanism was investigated.The results showed that, compared with material of gray cast iron of piston ring, chromium carbide/Ni3Al composite has a lower friction coefficient and wear rate, as well as the good cooperation of the material of friction components. The friction coefficient of chromium carbide/Ni3Al hardfacing layer is about 0.23, significantly lower than the friction coefficient of material of gray cast iron of piston ring is 0.39; The wear rate of chromium carbide/Ni3Al hardfacing layer is about 4.23679E-10 (mm3/Nm), significantly smaller than the wear rate of material of gray cast iron of piston ring is 9.7563E-10 (mm3/Nm). The sliding wear mechanism of pin-on-disc of hardfacing layer of Ni3Al strengthened by Cr3C2 is mainly slight abrasive wear and micro-cutting, showing a slight rub scratches. The good wear resistance of chromium/Ni3Al composite can be attributed to large volume fraction of reinforcement, the reasonable size distribution of reinforcements, strong phase interface bond and good mechanical properties of Ni3Al matrix.