Preparation,Wear Resistance And Corrosion Resistance Of N-doped Zirconium Based Bulk Amorphous Alloy

Zr-based bulk amorphous alloy shows more excellent performance because of its unique structure,and has broad application prospects in the fields of aviation and navigation,sports equipment,cell phone parts,biomedical treatment,etc.Element N,as a unique non-metallic material element,has a small atomic radius and a large negative mixing enthalpy and electronegativity difference with the metal element group in Zr-based amorphous alloy.However,there are relatively few studies on the addition of N elements to Zr-based amorphous alloys,and the mechanism of the effect of N elements on the compression properties,friction properties,and corrosion properties of Zr-based amorphous alloys is not clear.To this end,this thesis systematically investigates the effects of N doping on the wear resistance and corrosion performance of Zr-based bulk amorphous alloys by adding N elements to Zr-based amorphous alloys,reveals the frictional wear mechanism and corrosion mechanism,and provides theoretical guidance and scientific insight for experimental research and engineering applications of bulk amorphous alloys.In this thesis,bulk amorphous alloys with nominal compositions of Zr₅₅Cu₃₀Ni₅Al₁₀(N0)?(Zr₅₅Cu₃₀Ni₅Al₁₀)_99.5N_0.5(N0.5)?(Zr₅₅Cu₃₀Ni₅Al₁₀)₉₉N₁(N1)?(Zr₅₅Cu₃₀Ni₅Al₁₀)_98.5N_1.5(N1.5)?(Zr₅₅Cu₃₀Ni₅Al₁₀)₉₈N₂(N2)for bulk amorphous alloys.The amorphous structure of the samples was verified by X-ray diffractometer,the hardness and frictional wear properties of the samples were studied and analyzed by microhardness and tribological wear meters,the thermomechanical properties and corrosion properties of the samples were investigated by using differential scanning calorimeter and electrochemical workstation,and the frictional wear properties and corrosion properties of N-doped Zr-based amorphous alloys were observed by scanning electron microscope and energy spectrometer.The mechanism related to the influence of N-doped Zr-based amorphous alloy frictional wear performance and corrosion performance was analyzed in depth.The main results of the study are as follows.(1)The microhardness of the amorphous alloy samples showed a pattern of increasing and then slowly decreasing with the increase of N content,reaching a maximum value(579Hv)when the N doping amount was 1.5%,which was nearly 22%higher compared with N0;after that,the hardness value decreased with the increase of N content(up to 525Hv),which was10%higher compared with N0.The addition of N can effectively increase the stacking density of atoms in Zr-based bulk amorphous alloys,enhance the interatomic interaction forces in the alloy,and show higher hardness on a macroscopic scale.(2)In the load range of 10-30 N,the average friction coefficient of the samples fluctuates above and below the overall average friction coefficient,and there is no obvious connection with the variation of the applied load.The average friction coefficient of N1.5 amorphous alloy samples was 0.95,and the average friction coefficient of N0.5 amorphous alloy samples was 0.74.The wear rate decreased with the increase of N-doping of Zr-based amorphous alloy,and reached the minimum value(1.038×10^-3mm~3·N^-1·m^-1)at 1.5%N-doping,and slightly increased at 2%N-doping.The wear rate rebounded slightly at 2%N doping.Therefore,the appropriate addition of nitrogen can reduce the wear rate of Zr-based amorphous alloy.Among them,the wear rate of N1.5 is reduced by about 37.5%compared with the N0 sample.Under dry sliding friction conditions with GCr15 steel balls,the main wear mechanisms of N0 are abrasive wear,oxidation wear and corrosion wear,and those of N1.5 are adhesive wear,oxidation wear and abrasive wear.(3)The crystallization activation energies E_x(initial crystallization activation energy)and E_p(peak crystallization activation energy)of N0 at the characteristic temperature were 320.24±4.93 k J/mol and 298.31±5.45 k J/mol,respectively;the crystallization activation energies E_x and E_p of N1.5 at the characteristic temperature were 303.51±1.04 k J/mol and 310.99±The nitrogen doping lowers the potential barrier for crystal growth and raises the potential barrier for crystal growth.At the same time,the crystals are easier to nucleate,but difficult to grow.With the increase of crystallization volume fraction,the activation energy of nitrogen-containing amorphous alloy remained relatively constant,while the activation energy of N0showed a decreasing trend.the average activation energy of N1.5 samples was higher,and the overall performance was more difficult throughout the crystallization process.(4)The corrosion potential(E_corr)of N0 is-0.3897V and the corrosion current density(I_corr)is 9.129×10^-5A/cm~2;the E_corr of N1.5 is-0.3226V and the I_corr is 7.902×10^-8A/cm~2.The impedance of N1.5(10~5?/cm~2)is larger than that of N0(100?/cm~2).N1.5 has stronger resistance to corrosion in 0.9%Na Cl solution.The resistance Rf of the passivation film of the Zr-based amorphous alloy was significantly enhanced after N doping,and the corrosion diffusion effect on the sample surface was weakened and turned into a mild pitting effect,which improved the corrosion resistance of the Zr-based amorphous alloy.The oxidation and corrosion rate of the samples were slowed down and the main composition of the passivation film changed from Zr and Al oxides to an Al oxide.