The application of niobium in chemical equipment: Outstanding performance of anti-corrosion coatings and key components

The chemical industry has extremely high requirements for the corrosion resistance, high-temperature stability and mechanical strength of materials. Due to the fact that equipment such as chemical reactors and heat exchangers are exposed to harsh environments like strong acids, strong bases, high temperatures and high pressures for long periods of time, traditional stainless steel or nickel-based alloys often fail to meet the demands. Niobium, as a highly corrosion-resistant metal, the processed products such as niobium plates, niobium rods, niobium tubes, niobium targets, niobium foils, niobium blocks, niobium sheets, and niobium wires, due to their excellent anti-corrosion performance and high-temperature stability, have become the ideal choice for chemical equipment's anti-corrosion coatings and key components. Let's explore the application of these niobium products in chemical reactors and heat exchangers, analyze their anti-corrosion mechanisms, and look forward to future development trends.

The corrosion resistance of niobium far exceeds that of most metals, which provides a solid foundation for the application of niobium plates, rods, tubes, targets, foils, blocks, sheets, wires, etc. in chemical equipment. The main characteristics of niobium are attributed to: a stable passivation film, which forms a dense oxide niobium (Nb₂O₅) protective layer on the surface of niobium in an oxidative environment, effectively preventing further corrosion of niobium plates, rods, tubes, targets, foils, blocks, sheets, and wires; resistance to strong acid erosion, these niobium products perform exceptionally well in strong acids such as hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and nitric acid (HNO₃), especially remaining stable at high temperatures; resistance to halogen corrosion, having extremely strong resistance to halogen media such as chlorine (Cl₂) and bromine (Br₂), making them suitable for the chlor-alkali industry; resistance to molten salt corrosion, in molten salt reactors (such as in the nuclear energy and metallurgical industries), niobium's corrosion resistance is superior to titanium and zirconium. These characteristics make them ideal choices for anti-corrosion coatings and structural materials in chemical equipment.

In chemical reactors, niobium plates, niobium rods, niobium tubes, niobium targets, niobium foils, niobium blocks, niobium sheets, and niobium wires are widely used. In terms of anti-corrosion coatings, chemical reactors often fail due to corrosion by acidic or oxidizing media. Applying niobium coatings can significantly extend the equipment's lifespan. For example, niobium can be processed into coating materials through electro-deposition or thermal spraying technology, forming a niobium protective layer on the inner wall of the reactor, which is suitable for sulfuric acid production equipment; using explosion coating technology to combine niobium plates and niobium sheets with the steel substrate, it is used in high-pressure reactors to prevent hydrogen embrittlement and stress corrosion; through chemical vapor deposition (CVD), high-purity niobium sheets and niobium targets can be prepared to form films, which are used in corrosion-resistant reaction chambers in the semiconductor industry. In nitric acid production equipment, niobium sheet and niobium foil coatings can increase the reactor's lifespan by 3-5 times and reduce maintenance costs. In alloy reactor components, pure niobium has a relatively low strength and is usually alloyed with tantalum (Ta), molybdenum (Mo), etc. The niobium block combined with tantalum, molybdenum, etc. forms a Nb-Ta alloy, which has both high corrosion resistance and strength, and is used for stirring shafts and valves in strong acid environments; the niobium block combined with zirconium forms a Nb-Zr alloy, which can improve high-temperature oxidation resistance and is suitable for petrochemical cracking reactors, among which the niobium tube plays an important role in the material transportation of the reactor.

Heat exchangers are prone to corrosion and scaling in chemical production, and niobium provides an effective solution. In niobium tubular heat exchangers, both the niobium tubes themselves and the niobium-manufactured heat exchange tubes exhibit excellent resistance to acidic cooling fluids. In the hydrochloric acid regeneration system, their lifespan is longer than that of Hastelloy (a type of alloy); at the same time, niobium tubes and niobium heat exchange tubes are resistant to seawater corrosion, and when used in heat exchange systems for offshore platforms, they can avoid pitting corrosion caused by chloride ions. In niobium composite plate heat exchangers, titanium-niobium composite plates, with titanium providing strength and niobium plates serving as the corrosion-resistant layer, are used in phosphate production equipment; the graphite-niobium sheet and niobium foil combination can protect the graphite substrate in high-temperature corrosive gas heat exchange (such as in fluorine chemical production).

The niobium anti-corrosion technology has significant advantages in the application of chemical equipment, but it also faces challenges and has a clear future development trend. In terms of advantages, the corrosion rate of niobium in concentrated sulfuric acid is less than 0.01 mm/year, which is much better than stainless steel and has an extremely long service life; it can work stably in environments above 500°C, with strong high-temperature adaptability; although the price of niobium is high, the long service life reduces the overall cost. The challenge lies in the difficulty of processing these niobium products, their high hardness, and the need for specialized welding techniques (such as electron beam welding); in hydrogen environments, there is hydrogen embrittlement sensitivity, and niobium alloys (such as Nb-Hf) need to be used to alleviate it; currently, they are mainly imported, and cost reduction requires the development of recycling technology. The future development trends include: developing nano-niobium coatings to enhance the density and adhesion of niobium sheets, wires, and foils coatings through nanotechnology; using 3D printing technology to manufacture niobium blocks, plates, and tubes components to achieve rapid manufacturing of complex structure heat exchangers; developing niobium-ceramic composite materials, such as SiC-Nb for ultra-high temperature corrosive environments, where the niobium target can play a role in material preparation; researching green surface treatment processes and developing pollution-free anodizing processes for niobium wires, sheets, and foils.

Fortu Tech can produce and process Niobium billet, Niobium sheet, Niobium foil, Niobium plate, Niobium rod, Niobium wire, Niobium tubes.