The individual responsible for this process was a gentleman by the name of M.A. Hunter. The basic process created by Mr. Hunter involved mixing TiO2 with coke and chlorine. When heat was applied to the TiO2 the resulting product was TiCl4. Then sodium was used to reduce the TiCl4. At this point in time, the titanium produced by this method was used as an alloying agent in the production of steel.
TiO2 was a bi-product of the process developed by Hunter and it was determined that it had the characteristics necessary to make it a great white pigment. As a result it was used in paint specifically for this reason.
Although the Hunter process was a viable method to extract the metal from the ore, it proved not conducive to large scale manufacturing efforts. A gentleman by the name of Dr. Wilhelm Kroll is the man credited with creating a process that reduced titanium effectively on a large scale basis. The process used magnesium as the reducing agent, as opposed to the sodium previously used by Hunter. This process was named after its founder and is known today as the Kroll process.
Although the Kroll Process was a major improvement in the extraction process, it did leave a chloride residue and it also did not recover the unreacted magnesium metal. This contamination was addressed very successfully with the application of vacuum distillation. Currently, the Kroll Process, combined with Vacuum Distillation is the typical method of extracting the metal from the ore.
In the mid 1940’s, the US Department of Defense determined titanium to be the “metal of choice” in military aircraft. This recognition was based on the facts that titanium was commercially available combined with the metallurgical characteristics of the metal, including the strength to weight ratio, the corrosion resistance as well as its ability to perform at high temperatures. The first aircraft titanium was designed into was the Douglas Aircraft X3 Stilletto.
For decades titanium was considered an “aerospace metal” and was used exclusively in this application. As time went on, the corrosion properties of the metal were explored in non-aerospace applications, specifically as a tubing product used in heat exchangers for power generation. This application proved to be extremely successful and the “industrial” market was created.
The corrosion resistance properties of titanium began the industrial application evolution of metal; however it did not stop there. As the market became more familiar with the metal, it was designed into other applications as well, all based on maximizing the unique characteristics of titanium. Chemical process equipment such as pressure vessels, heat transfer equipment, piping systems and reverse osmosis lead the way. Examples of applications that have emerged over the past 25 years include medical applications such as implants and wheelchairs. Titanium found its way into recreational applications such as golf clubs, tennis rackets, and bicycles. Titanium can be found in automotive and architectural applications. The Guggenheim Museum in Balboa Spain is a great example of this. Titanium jewelry is a common consumer item and can be worn by many people who have a reaction to other metals. The applications for titanium continue to evolve as people recognize the unique qualities this metal has to offer.
