Preparation Method Of Porous Titanium Coating

Preparation method of porous titanium coating

Porous titanium foam and its alloys combine the characteristics of titanium alloy and porous material, which can reduce the weight of the material without weakening its strength, while maintaining high toughness and corrosion resistance.

It is understood that titanium foam and its alloys have important application value in some special fields, especially in the biomedical industry. Because porous titanium has both high biocompatibility and excellent mechanical properties, its advantages are very obvious.Compared with the overall porous titanium material, the titanium material that is only porous on the surface has higher mechanical strength and can withstand greater physiological loads, thus showing broader application prospects in the medical field.

Recently, the work of the Chinese Academy of Weapons Sciences has proved that the perfect combination of cold spraying technology and vacuum distillation can prepare a pure titanium coating with a penetrating porous structure.

The method is to prepare a Ti-Mg composite coating by cold spraying technology, and the preparation of a porous titanium coating is realized by vacuum distillation of the Mg in the coating.They used homemade Ti powder and Mg powder, which were physically mixed with a mass ratio of 80:20, as the spraying powder for the coating.The selected substrate for spraying is TC4 grade titanium alloy (0.002%H, 0.07%O, 0.02%N, 0.02%C, 0.04%Fe, 6.2%Al, 4.1%V, TiBal).Ti-Mg composite coating is prepared by high-speed and high-pressure cold spraying equipment. The working gas is N2, the working pressure is 3.0MPa, the gas heating temperature is 300℃, and the spraying distance is 25mm.Then, a vacuum sintering furnace is used to vacuum distillation of the sprayed Ti-Mg composite coating, with a chamber pressure of 2.0~2.3MPa, a distillation temperature of 1100℃, and a distillation time of 2h.

The test showed that the binding interface between the obtained coating and the substrate is relatively tight, the density of the coating is higher, the average thickness is about 250µm, and the distribution of the two components in the coating is relatively uniform.After measurement, the binding strength of the coating and the substrate reached 60MPa, and the porosity of the coating was less than 1%.The composition analysis of the surface was carried out using an energy spectrum analyzer. The results showed that the titanium particles in the coating did not have obvious oxygen content, indicating that the cold spraying technology avoided excessive oxidation of titanium powder well, which was conducive to retaining the original chemical composition of the sprayed powder; However, the magnesium particles in the coating were found to have more impurities, which was mainly due to the high activity of magnesium metal and natural oxidation in the atmosphere.In order to make the coating porous, the magnesium component in the sprayed coating must be removed, so the sprayed coating is vacuum distilled.After vacuum distillation, there is a significant through-hole structure in the microstructure of the coating, the porosity of the coating reaches 50%, and the pore size distribution is 30~100µm.The results of energy spectrum analysis on the surface of the coating show that only the titanium component exists after the vacuum distillation treatment of the coating, and the magnesium component has been completely distilled.