Titanium Anode Plate Processing and Usage Guidelines

I. Base Material: Titanium

Titanium is a metallic element, gray in color, with an atomic number of 22 and an atomic mass of 47.867. It can burn in nitrogen and has a high melting point. Titanium and titanium-based alloys are novel structural materials mainly used in the aerospace and marine industries. With its high melting point, low density, high strength-to-weight ratio, good ductility, excellent corrosion resistance to acids and bases, low thermal conductivity, stability across a wide temperature range, and minimal stress under rapid heating and cooling, titanium’s commercial value has been recognized since the 1950s. It has since been applied in high-tech fields like aviation and aerospace. As its applications expand into industries such as chemical processing, petroleum, power generation, desalination, construction, and everyday products, titanium has increasingly become known as a modern, versatile, and strategic metal critical for enhancing national defense equipment.

1. Physical Properties: Pure titanium has a silver-white appearance and possesses the following unique characteristics compared to other metals:

• High melting point of 1660°C.
• Dense hexagonal close-packed crystal structure at room temperatures (below 885°C) and a body-centered cubic structure above 885°C, with a volume increase of approximately 5.5%.
• Density of about 4.51 g/cm³, approximately 60% of stainless steel’s density and about 60% greater than aluminum’s.
• Tensile strength of pure titanium ranges from 350 to 700 MPa, with titanium alloys reaching 700 to 1200 MPa or even up to 1400 MPa. The strength-to-weight ratio of titanium alloys surpasses that of any other material.
• Specific heat, thermal conductivity, and electrical resistivity are similar to stainless steel, though titanium’s thermal expansion coefficient is 50% less. Titanium has low thermal and electrical conductivity, comparable to stainless steel.
• Lower modulus of elasticity than stainless steel, making it easier to bend under lower stress levels.
• Exhibits stable creep characteristics within the 200–300°C range.

1. Chemical Properties:

• Reaction with Acids: Titanium does not easily react with inorganic acids at room temperature but may react when heated.
• Reaction with Bases: Titanium reacts slowly with common alkaline solutions and does not react with dilute bases.
• Reaction with Non-metals: Titanium is relatively inert under normal conditions, but at high temperatures, it can form stable, hard, and insoluble interstitial compounds with many non-metals.
• Gas Absorption: Titanium’s significant characteristic is its ability to absorb gases (oxygen, nitrogen, and hydrogen) vigorously. Its reaction with oxygen and nitrogen is irreversible, making titanium an excellent getter. However, absorbed gases can be removed by heating titanium in a vacuum to 800–900°C.

1. Machinability: Titanium’s strength-to-density ratio exceeds that of iron and aluminum. It is twice as strong as pure iron and five times stronger than pure aluminum.

II. Titanium Anodes

Titanium anodes, fully termed as metal oxide-coated titanium anodes (MMO), are also known as dimensionally stable anodes (DSA). Using titanium as the base material, these anodes are coated with a precious metal layer, giving them excellent electrocatalytic and conductive properties.

Compared with conventional graphite and lead anodes, titanium anodes have the following advantages:

1. Stable electrode dimensions, ensuring a consistent inter-electrode gap during electrolysis and maintaining a stable cell voltage.
2. Catalytic effect, with low operating voltage.
3. Low operating voltage, reducing energy consumption and saving direct current usage by 10%-20%.
4. Long service life; in diaphragm-based industrial applications, metal anodes demonstrate resistance to chlorine and alkali corrosion, lasting 5–7 years, while graphite anodes last only about eight months.
5. Resolves the dissolution issues associated with graphite and lead anodes, preventing electrolyte and cathode contamination, thus improving product purity.
6. Allows higher current density, enhancing electrolysis efficiency.
7. Composed of iridium and ruthenium oxides, providing strong corrosion resistance.
8. Prevents short circuits caused by deformed lead anodes, increasing current efficiency.
9. Lightweight compared to graphite and lead anodes, reducing labor intensity.
10. Titanium substrate allows for precision manufacturing and high accuracy.
11. Substrate can be reused if undamaged.

Titanium Anode Types:

1. Chlorine-Evolving Anode (Ruthenium-based Coated Titanium Anode): Suitable for electrolytes with high chloride ion content, such as seawater or brine electrolysis. Our products include ruthenium-iridium titanium anodes and ruthenium-iridium-tin titanium anodes.
2. Oxygen-Evolving Anode (Iridium-based Coated Titanium Anode): Suitable for sulfuric acid environments. Our products include iridium-tantalum anodes, iridium-tantalum-tin titanium anodes, and high-iridium titanium anodes.
3. Platinum-Coated Anode: Uses titanium as the base material with a platinum coating thickness typically between 0.5–5 μm. Platinum titanium mesh sizes are generally 12.5×4.5 mm or 6×3.5 mm.

III. Overview of Production Process

1. Choose TA1 grade titanium base material, ensuring a smooth, defect-free surface without scratches, peeling, cracks, or layering.
2. Machine the selected titanium substrate to meet customer specifications.
3. Anneal and level the titanium base at 600°C.
4. Annealing results in a dense titanium oxide layer on the surface, which is mechanically polished to reveal the metallic luster.
5. Etch the titanium substrate in 10% oxalic acid at a mild boiling state for 10 hours to remove the surface oxide layer.
6. Configure the precious metal solution according to the customer’s specified anode environment.
7. Inspect the acid-etched titanium substrate for a uniform gray surface texture, then apply the precious metal solution by hand. Sinter the coated substrate at a set temperature and allow it to cool to room temperature before applying the next layer, repeating until 18–22 layers are applied.
8. Upon completing the sintering process, perform a lifespan test on the batch sample, and, if approved, package and ship the finished product.