Ru-Sn-Ti oxide coatings with different Sn element ratios were prepared on titanium substrates by thermal decomposition method; the effect of temperature on the electrochemical properties of titanium electrode coatings was investigated. The physical and electrochemical properties of the oxide-coated electrodes were investigated by scanning electron microscopy, X-ray diffraction, and anodic polarization curves. The results show that the ternary coating prepared by thermal decomposition method at 375 ℃ and Sn accounts for 4% by mass, the surface structure of the coating is uniform and fine, the crack width is small, and the grain size is the best. Best performance.

Titanium electrode plate material is an insoluble anode material that is widely used in the electrochemical industry, also known as dimensionally stable anode, or DSA. It is a new type of high-efficiency electrode material developed in the late 1960s, with titanium metal as the matrix and precious metal oxide as the surface active coating. Titanium electrodes were first used in the chlor-alkali industry and are now widely used

Used in chemical, metallurgy, electroplating, water treatment, environmental protection, marine, cathodic protection and other fields.

The successful application of titanium-based noble metal-coated electrodes in the chlor-alkali industry has inspired the use of acidic oxygen-evolving titanium electrodes. However, when the Ru-based coated electrode is used in sulfuric acid electrolyte, due to the large number of surface cracks, the active oxygen precipitated during the electrolysis process easily penetrates into the surface of the titanium substrate, resulting in the formation of a TiO2 passivation film between the titanium substrate and the coating, increasing the size of the electrode. internal resistance. In addition, the Ru-based coating has problems such as poor bonding force with the titanium substrate during the acid electrolysis process, the coating is easy to fall off, and the electrode fails. And studies have found that doping metal oxides that form solid solutions with Ru and Ti in the coating is an effective way to improve the performance of metal oxide anode coatings. The atomic radius of Sn is very similar to that of Ru and Ti. SnO2 has the same rutile crystal structure as RuO2 and TiO2, and it is easier to form a rutile solid solution. For this reason, this study started from improving the oxidation resistance of the coating and increasing the activity of the coating, adding Sn in the coating, exploring the optimization effect of Sn on the electrochemical performance of the titanium electrode coating, and reducing the amount of precious metal Ru to Reduce costs and save materials; secondly, by changing the sintering temperature, the effect of temperature on the electrochemical properties of titanium electrode coatings is explored, and the optimal process of ternary titanium electrode coatings is finally obtained.

Coating Surface Topography Analysis

Figure 1 shows the surface morphologies of Ti electrode coating materials prepared at the same temperature (450 °C) with different Sn contents. It can be seen that the surface of the coating exhibits the typical "tortoise cracks" of thermally decomposed coatings. Figure 1(a), (b), (c) The cracks on the coating surface are wide and uneven, and the crack surface is broken. There are a large number of diffusion channels in the coating with this morphology, which provides convenience for the penetration of the electrolyte, so that the oxygen precipitated on the surface of the electrode coating can easily reach the substrate to form TiO2, resulting in the coating

Passivation, the electrode loses activity. In Figures 1(d) and (e), with the increase of Sn content, the cracks on the surface of the oxide coating become narrower and shallower, indicating that the bonding between the coating and the substrate has improved, and the rutile phase solid solution formed by SnO2 and TiO2 The adhesion between the coating and the Ti substrate is increased, and the bonding effect of the coating itself is also enhanced, which hinders the penetration of the electrolyte to the titanium substrate through the cracks and pores of the coating and the formation of TiO2, and improves the disadvantage of the coating being easily peeled off.

In addition, it can be seen that the oxide coating becomes smoother and denser, and the crack plate becomes smaller. This structure shows that the addition of Sn plays a role in refining the particles, thereby increasing the specific surface area of the coating, thereby enhancing the coating. activity. Finally, SnO2 itself as a good conductor and its acid and alkali resistance enhance the activity and life of the coating. When the Sn content is 5%, the clustered

The precipitation of the particles becomes stronger, which greatly reduces the area of the flat area, indicating that the segregation of active elements may occur in these places, and the coating is unevenly distributed, which affects the stability of the coating. To sum up, the coating with Sn content of 4% is ideal.

Therefore we judge:

(1) Micro-arc oxidation composite coating containing carbon nanotubes can be prepared on the surface of titanium alloy by adding well-dispersed carbon nanotubes in the basic electrolyte of sodium silicate.

(2) Both coatings are relatively dense, but the addition of carbon nanotubes makes the surface smooth and the surface roughness decreases from 1.39 μm to 1.04 μm. The thickness of the WTC coating was 22 μm, while the thickness of the TJC composite coating was slightly lower at 20 μm.

(3) The microhardness of the two coatings is higher than that of the substrate. The microhardness of the WTC coating is 550HV, while the microhardness of the TJC composite coating is the highest, which is 680HV, which is twice as high as that of the substrate. many. When the Sn content increases, the grain size of the main products in the surface layer gradually decreases, and cracks appear in the coating of the sample surface. The width is the smallest, the density is the largest, and the electrochemical performance is the best.