In addition to oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, titanium reserves in the Earth accounted for the ninth place, its reserves of about 0.44% to 0.57%, belongs to the reserves of more elements. Titanium in the pure state of its color is silver-white, at the same time has a metallic luster, a very high melting point, is a relatively insoluble metal. Titanium has two isomers are α-Ti and β-Ti, α-Ti is a close-packed hexagonal structure, only below 882 ° C to maintain stability, when more than 882 ° C, α-Ti will be transformed into β-Ti, β-Ti is a body-centered cubic structure, it can remain stable between 882 ° C and 1678 ° C.

Since its discovery, titanium has been widely concerned by people, and scientists have never stopped their research and exploration of it. Now we have a more in-depth understanding of the properties of titanium. Titanium and titanium alloys have many advantages, such as high density, high specific strength, corrosion resistance and high temperature resistance, good mechanical and mechanical properties, light weight, etc. They develop rapidly with these excellent properties. It has been widely used in all walks of life, such as chemical industry, aerospace, medical materials, electronics industry and other fields, compared with other metals, titanium also has excellent biocompatibility, and the elastic modulus of the human femoral head is very close to, so the use of titanium for the preparation of biological materials for the treatment of some human diseases has great help.

Although titanium and titanium alloys have incomparable advantages to other metals, with the progress of society and the development of science, their own performance has been unable to meet the needs of human production and life. How to modify them to break through the limitations of their use has become an urgent problem to be solved. Compared with traditional materials, nanomaterials have more superior performance. Therefore, people think of the application of nanotechnology in titanium and titanium alloys, so that its application is more extensive. Nowadays, the direct preparation of nano-body materials has high cost and small output, and the standard requirements for equipment and materials are harsh, while the surface nano technology is relatively low in hardware conditions such as equipment, small cost, simple and mature operation technology, and can meet the production needs to a certain extent, so the surface nano of titanium and titanium alloy is directly applied to improve or improve its performance. Enhance its application value.

There are many methods to modify the surface of titanium and titanium alloys, such as sol-gel method, hydrothermal method, template method, anodic oxidation method and electrochemical deposition method. Among these many methods, anodizing treatment on titanium and titanium alloy is a simple and effective surface treatment method, compared with other methods, the method is simple to operate and low cost, so here is a brief description of this surface treatment method.

Anodizing is an electrochemical method to produce a layer of oxide film on a metal or alloy, and the specimen is placed in it after the plating solution is configured in advance. Anodizing occurs on the surface of the specimen by setting the voltage or current to produce an oxide film. For titanium and its alloys, the electrolyte concentration, the size of the voltage and current and the length of the reaction time can be adjusted. A long set of short, controllable tube diameter TiO 2 nanotubes are obtained, thus realizing the surface nanization of the specimen. These tubes grow from the surface of the specimen base and are closely combined with the base. The experimental principle of tio2 and titanium alloy surface preparation of TiO 2 nanotubes by anodic oxidation is summarized.

①Ti+2H 2O = TiO 2+4H ++4e (the process actually consists of 2H 2O→O 2+4e+4H +Ti+O 2→TiO 2)/②TiO 2+6F -+4H +＝[TiF 6] 2-+2H 2O

By observing the reaction formula, it can be seen that there are mainly two reaction processes: one is the formation process of TiO 2, and the other is the dissolution process of TiO 2. The formation of TiO 2 is carried out in an electrochemical environment, while the process of TiO 2 dissolution is a chemical reaction, and the two reactions are repeated to produce the nanotubes. The current also plays a key role in the process of anodizing reaction, and the generation of TiO 2 nanotubes can also be divided into three stages according to current and time。

In the first stage, the TiO oxide layer is formed, and the reaction has just started, and the resistance is small but a huge current is generated. The TiO film is generated on the surface of Ti, which is called the barrier layer. In the second stage, the barrier layer of the TiO film generated in the first stage begins to dissolve. When the barrier layer reaches a certain thickness, the current in the circuit gradually returns to a stable state. At this time, the TiO film partially dissolves, resulting in many small holes. In the third stage, TiO nanotubes are formed, and the micro-pores formed in the second stage cause the surface electric potential of the specimen to be uneven, and the electric field mostly accumulates in the low concave of the pores, which accelerates the oxidation in this region. Meanwhile, the Ti 4 produced by the oxidation reaction moves the oxide layer continuously with the reaction, resulting in the dissolution of the oxide layer, while the oxidation layer at the top of the nanopore dissolves slowly. The oxidation layer at the bottom of the hole caused by the electric potential dissolves quickly, so the small pores originally generated continue to dissolve and extend, and gradually produce nanotubes. With the increase of reaction time, the dissolution reaction rate at the bottom of the hole and the top of the hole are gradually consistent, and the length of the nanotubes remains unchanged.

The development of science and technology continues to advance, the degree of social civilization continues to improve, with the progress of science and technology, titanium and titanium alloy application field is expanding, people's requirements for material performance further improve, titanium and titanium alloy will be toward high temperature resistance, higher strength, more excellent plasticity, better wear resistance direction, and titanium alloy with comprehensive performance will also be produced. Titanium alloy surface treatment technology will develop in a more advanced direction, and the surface friction resistance, acid resistance and corrosion resistance of titanium alloy after surface nano treatment will be further improved, and titanium and titanium alloy will achieve greater development in the new era.

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