What is Titanium Sponge?

Image Credit: 
Main Image: 
Titanium sponge

Titanium Sponge is a porous form of titanium that is created during the first stage of processing. In its natural form, titanium is broadly available within the earth’s crust. Although purified titanium is quite costly, it is available in its basic form, in almost all living creatures. It can also be found in rocks, water and soil. After being extracted, it is processed to remove excess materials and convert it into a usable, although costly, product. Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant (including sea water, aqua regia and chlorine) transition metal (metal in periodic table) with a silver color. The two most useful properties of the metal form are corrosion resistance and the highest strength-to-weight ratio of any metal.


What is the History of Titanium sponge?

Titanium was discovered in Cornwall, United Kingdom, in 1791 by amateur geologist and Pastor, William Gregor. The processes required to extract titanium from its various ores are laborious and costly; it is not possible to reduce in the normal manner, by heating in the presence of carbon, because that produces titanium carbide. Pure metallic titanium (99.9%) was first prepared in 1910 by Matthew A. Hunter, a metallurgist by heating TiCl4 with sodium in a steel bomb at 700–800 °C in the Hunter process. The Hunter process was the first industrial process to produce pure ductile metallic titanium. Titanium metal was not used outside the laboratory until 1932 when William Justin Kroll, a metallurgist proved that it could be produced by reducing titanium tetrachloride (TiCl4) with calcium. Eight years later he refined this process by using magnesium and even sodium in what became known as the Kroll process. Although research continues into more efficient and cheaper processes, the Kroll process is still used for commercial production.


What is known as Kroll process?

The conversion process used with raw titanium is called the Kroll process. Kroll Process is a pyro-metallurgical (a branch of extractive metallurgy) industrial process used to produce metallic titanium. Kroll's titanium was highly ductile reflecting its high purity. The Kroll process displaced the Hunter process and continues to be the dominant technology for the production of titanium metal, as well as driving the majority of the world's production of magnesium metal. Refined Rutile (or ilmenite) from the ore is reduced with petroleum-derived coke in a fluidized bed reactor at 1000° C. Rutile is a mineral composed primarily of titanium dioxide, TiO2. A fluidized bed reactor (FBR) is a type of reactor device that can be used to carry out a variety of multi-phase chemical reactions. The mixture is then treated with chlorine gas, affording titanium tetrachloride (TiCl4) and other volatile chlorides, which are subsequently separated by continuous fractional distillation (separation of a mixture into its component fractions based on their different boiling points). In a separate reactor, the TiCl4 is reduced by liquid magnesium (15-20% excess) at 800-850° C in a stainless steel retort to ensure complete reduction. The chemical reaction is:


2Mg (l) + TiCl4 (g) --> 2MgCl2 (l) + Ti (s); (at 800-850° C), where, l, g, and s are liquid, gas and solid phases


Complications result from partial reduction of the TiCl4 to its lower chlorides TiCl2 and TiCl3. The resulting porous “metallic titanium sponge” is purified by leaching (method of extracting valuable material, usually metals, from ore) or vacuum distillation. The sponge is jack hammered out, crushed, and pressed before it is melted in a consumable electrode vacuum arc furnace. The melted ingot is allowed to solidify under vacuum. An ingot is a material, usually metal, that is cast into a shape suitable for further processing. At this point, the converted titanium sponge is ready for fabrication. Some firms sell titanium sponge as a finished product, while others complete the conversion process internally. The sponge can now be formed into mill shapes such as a bar, plate, sheet or tube. These products are then shipped to different mills and fabricators to created finished products for commercial use. The MgCl2 (magnesium chloride) can be further refined back to magnesium.


What are the applications of Titanium  and Titanium sponge?

  • Due to their high tensile strength to density ratio. high corrosion resistance, fatigue resistance, high crack resistance, and ability to withstand moderately high temperatures without creeping, titanium alloys are used in aircraft, armor plating, naval ships, spacecraft, and missiles.
  • Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other elements, to produce strong lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals, desalination plants, pulp, and paper), automotive, agri-food, orthopedic implants, dental and endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications.
  • As a matter of fact, about two thirds of all titanium metal produced is used in aircraft engines and frames.
  • Pigments, additives and coating: About 95% of titanium ore are refined into titanium dioxide (TiO2), an intensely white permanent pigment used in paints, paper, toothpaste, and plastics. It is also used in cement, in gemstones, as an optical opacifier in paper, and a strengthening agent in graphite composite fishing rods and golf clubs.
  • Titanium sponges are utilized by the aerospace industry for uses including crucial engine parts, by general industry, mainly for uses such as plate heat exchangers, and also as an additive in manufacturing special stainless steels. The titanium sponge used for crucial engine parts in particular is called a premium grade, and is manufactured under extremely strict quality control.
  • Titanium sponge is the product in it's purest form and is used as the base of for titanium alloys, billets, ingots, etc.


What are the Benefits of Titanium sponges?

The benefits are:

  • It has a high Resistance to corrosion and also it is Fire and shock resistant.
  • Titanium sponge is very Light-weight.
  • It has a Low cost of maintenance.
  • It is Biocompatible and also Recyclable.


What are the main countries that manufacture Titanium Sponge?

The main countries manufacturing Titanium Sponge include: US, China, Japan, UK, and recently India. India very recently join the select group of nations possessing the technology for industrial scale production of titanium sponge and titanium. ISRO, the Indian Space Research Organization has always depended on overseas markets to source titanium sponge, which is created during the first stage of processing titanium ore. It is the raw material used to make alloys that are used to make rockets. Very soon, ISRO will be able to source titanium sponge from a new plant, one of the few in the world being put up by Kerala Minerals and Metals, or KMML. India will be the seventh country in the world to have the technology to make titanium sponge. The breakthrough is a result of pooling of resources among state-run organizations and companies. The technology was developed by Defense Metallurgical Research Laboratory, a laboratory under Defense Research and Development Organization, or DRDO. It cost KMML Rs. 143 crore (INR) to set up the facility and the tab is being picked up by ISRO’s Vikram Sarabhai Space Centre in Kerala. The job of converting titanium sponge to titanium alloy will be done by the Hyderabad-based company.


External References