The H.C. Starck Solutions centennial celebration is almost ending. During 2020, we have alternately reflected on the equipment, the facilities, and – indeed – the personnel who have helped build our global reputation for excellence in the field of refractory metals. It has also given us an opportunity to look back on some of our greatest successes with a view to understanding how all the largest milestones are reached in incremental steps.

This month, we are shining the spotlight on our expertise in the chemical process industry (CPI) with a focus on the extensive research and development (R&D) our teams have carried out into novel corrosion-resistant systems based on niobium and tantalum alloys.

Why Use Niobium & Tantalum Alloys in the CPI?

The CPI has grown dramatically and, that growth has yielded a host of new processes and supply-demand issues. Complicating the development pipeline for this already complex industry is the need to push the limits of materials science and achieving superior corrosion-resistant solutions for new processes. Modern chemical plants require materials that can deliver high-temperature and high-pressure service in increasingly concentrated acids with longer lifetime. Tantalum alloys continue to fill a niche in applications where long-life, reliability, maintenance-free and rapid heat transfer are required.

Tantalum alloys owe their exceptional corrosion resistant properties to a thin surface layer of tantalum oxide (Ta2O5) that forms on the metal’s surface when exposed to oxygen.  This adherent, self-passivating protective layer is extremely stable, defect-free, and capable of spontaneously reforming in the event of damage.

With similar properties but less resistance to chemical attack, lower mechanical strength, and a lower cost than that of tantalum, niobium covers an important niche in the world of CPI.

Since the early 1970s, the tantalum alloy Ta2.5W (patented in July 1971) became the standard CPI material, replacing pure tantalum due to its high mechanical strength and superior corrosion-resistant properties. Ta2.5W offers an exceptional combination of mechanical strength, high corrosion, hydrogen embrittlement resistance, and high thermal conductivity making it an ideal material for tubing or sheet used in heat exchangers, reactors, and other critical chemical equipment.

In 1976, H.C. Starck registered the trademark NRC®76 for Ta2.5W made in Newton, MA, USA (a suburb of Boston). Manufactured via in-house electron-beam, vacuum arc melting, and a combination of thermo-mechanical processes refined over decades, our signature NRC®76 welded tubing offers the customer a defect-free product with a tightly controlled composition and most importantly uniform wall thickness which is paramount in engineering calculations to secure safety for many years in operation.

Once our NRC®76 got the prestigious German TÜV certification the alloy became the undisputed leading tantalum alloy in the global CPI market.

A unique NRC76 (Ta2.5W) product of our plant in Newton, MA, the E-clad sheet is the only large tantalum sheet in the market which features excellent surface quality and best-in-class flatness, making it the choice solution for explosion cladding.

Our Research into Novel Tantalum Alloys

Around 2010, we pioneered research into new tantalum alloys with greater corrosion and hydrogen embrittlement resistance. Little progress had been made by other players in the industry since the genesis of Ta2.5W almost forty years prior. H.C. Starck Solutions developed and patented the ULTRA 76 tantalum alloy (US patent 9,725,793 issued April 2017) which shows dramatically improved corrosion and hydrogen embrittlement rates in hot and concentrated hydrochloric and sulphuric acids (which constitute the majority of applications for tantalum in the CPI).

Responding to market pressure to reduce the cost of ULTRA 76, additional work resulted in the development of ULTRA76+, a modified Ta2.5W alloy with significantly improved mechanical and anti-corrosion properties and a reduced cost when compared with the previous the generation (ULTRA76). ULTRA76+ is patented across the world and already generating value to customers in need of solutions in extreme corrosion environments.

Continuing the tradition of leadership in this field, H.C. Starck Solutions carried out advanced R&D into new alloying systems and have developed and patented a family of niobium alloys with superior properties compared with pure Nb for CPI (patent no. 9187802, Nov 2015).

As a key player in the industry, H.C. Starck Solutions contributed throughout the years to standardizing the material and product requirements for the CPI industry being an integral part of the ASTM B10 Committee (Reactive and Refractory Metals and Alloys – Subcommittee B10.03 Ta &Nb).

The Future of Niobium & Tantalum Alloys

We are keenly and actively engaged in the future of the CPI industry by constantly working with customers to develop creative solutions. Some of the most exciting work involves the creation of powders and wire used as feedstock in additive manufacturing but, even more exciting, the creation of advanced solutions for CPI by using 3D printing to develop and produce highly advanced equipment for extreme performance in challenging operational conditions.

Looking for tantalum alloys?

At H.C. Starck Solutions, it is incredibly important to us that all our growth be sustainable. Throughout the years, our vertical integration as well as continuous technical progress developed us into a manufacturer that champions societal progress through sustainable technological innovation. We recycle an ever-increasing percentage of the niobium and tantalum alloys we use for production ever year. Want to learn more? Contact a member of the team today. Or, refer back to our 100 Years of Refractory Metals Expertise page to learn more about our centennial celebration.