Research On Pulse Oxygenation And Surface Properties Of Pure Titanium

Titanium metal materials have been widely used in life,medicine,industry and other fields due to their excellent comprehensive properties,but their wear resistance is poor and corrosion resistance is limited,still can not fill such as titanium jewelry,porcelain teeth,titanium-steel ship board and other applications in special fields.In this paper,the pulsed oxygenation method was used to treat pure titanium samples,and the continuous oxygenation samples were used as the reference.The surface morphology and phase composition of samples were observed by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The hardness and elastic modulus of samples were measured by nanoindenter.The surface friction coefficient curve and wear acreage of the samples were tested by wear testing machine,In addition,corrosion tests were set up to simulate the corrosion rate and corrosion characteristic curves of samples in body fluid and seawater environment respectively.At the same time,the wear mechanism and corrosion resistance mechanism of oxygenation samples are proposed in this paper,which provides experimental and theoretical basis for the further application of titanium metal materials.The research shows:1.With the prolongation of oxygenation time or temperature increase,the oxide layers of different thickness is formed on the surface of the samples.The oxide layer is lamellar and composed of different titanium oxides.In the range of 500 to 700°C,the surface oxide layer of the oxygenation samples are well combined with the titanium matrix.The oxide layer of the continuous oxygenation sample is large area shedding for6h at 800°C due to the different composition,structure and thermal expansion coefficient of different oxides.Pulsed oxygenation for 6h,the oxide layer of the sample was well bonded to the titanium matrix and no obvious shedding occurred.2.Oxygenation treatment can improve the surface hardness of pure titanium.The maximum microhardness of pulse oxygenation sample for 6h at 600°C is 15.390 GPa,which is about 7.3 times of the original sample.The surface hardness of continuous oxygen sample is 9.292 GPa,which is 4.4 times of the original sample,but only 60%of pulse oxygen sample.The maximum surface elastic modulus of the two oxygen treatments were achieved at 700 C for 4.5 h,228.027 GPa under pulse oxygen sample and 221.523 GPa under continuous oxygen sample respectively,compared with the original sample,the surface elastic modulus is improved by 94.4%and 88.8%,The deformation resistance of pure titanium is improved evidently.3.The minimum surface friction coefficient of the continuous oxygenation sample is 0.3012,and the minimum wear acreage is 3876.08μm~2;the minimum surface friction coefficient of the pulsed oxygenation sample for 4.5h at 800°C is 0.2373,and the minimum wear acreage is 317.44μm~2,which is only 0.92%of the original sample.Oxygenation treatment significantly improves the friction and wear properties of pure titanium,weakening the adhesive wear effect.4.The minimum corrosion rate of the pulsed oxygenation sample in the simulated body fluid is 0.037 mm/h for 4.5h at 800°C,which is 3.96%of the original sample;in simulated seawater the minimum corrosion rate is 0.090 mm/h,about 7.49%of the original sample.For 4.5h at 800°C in the two media,the open titanium potential of the pure titanium sample is higher,the AC impedance is larger,the self-corrosion potential is higher,and the corrosion resistance is better.