Zirconium and Titanium Flowformed Products Offer Myriad of Advantages

For years, large scale, economical production of thin-walled, seamless zirconium tubing has been little more than a pipe dream. Plant operators dreamed of a day when the use of ultra corrosion resistant zirconium alloys for applications like transfer piping would be feasible.

The reality is, that day is here? Using an advanced cold forming process called flowforming, Zircadyne Zirconium products, like 4 in. sch 5 zirconium pipe, are available today. Products from other alloys are also being developed.

Dynamic Machine Works (Billerica, Massachusetts) is a leading pioneer in the flowforming process, producing tube and pipe in lengths up to 22 feet and diameters from 1 inch to 25 inches, depending on the material. The company has been working with Oremet-Wah Chang since 1996 to develop and produce thin-walled zirconium and titanium products.

Today, flowforming of precise and seamless zirconium and titanium tubes and pipes with superior finishes and enhanced mechanical properties is not only a reality but a common occurrence. Dynamic and Oremet-Wah Chang are presently investigating market opportunities for a line of tubes and pipes made out of Titanium 6Al 4V, which has been successfully flowformed recently into net shapes.

From its founding as a precision machining business in 1973, Dynamic began its involvement with flowforming in the mid-1980s. A short time later, Ven Fonte, Dynamic's Founder and

Zirconium preform at the beginning of the flowforming process

President, decided to make flowforming his company's only business. Pushing the envelope with unique metals, such as zirconium alloys, is a challenge Mr. Fonte enjoys. Like so many other projects, Fonte and his Dynamic team have taken zirconium head-on and succeeded.

Mr. Fonte attributes this success in large-part to teamwork. "Oremet-Wah Chang's years of experience with zirconium was an important ingredient in Dynamic's ability to fully understand the behavior of this metal and subsequently develop the necessary flowforming parameters capable to routinely produce seamless, economical pipes with excellent metallurgical properties," he said. "Dynamic's success in flowforming pipes with integral stub ends, thus eliminating welding, was a direct result of our collaboration with Oremet-Wah Chang. Their intimate knowledge of zirconium products and applications teamed with a strong desire to develop and offer the market what was not available before, proved to be the guidance necessary in any technological advance."

"Although both companies have certainly gained from this close cooperation, I truly believe that, ultimately, the greatest benefit will go to the end-user: availability of superior, seamless pipe at or near the cost of rolled and welded products," Mr. Fonte said. Other important advantages offered through flowforming include:

• Highly precise, seamless construction to net shapes

• Increased mechanical properties

•Tubular, conical, ogival and contoured geometrics

• Uniform, axially-directional and stable grain structure

• Surface finishes to eight micro-inch

• Very high diameter-to-length ratios

•Repeatable accuracy - part to part, lot to lot

For the insatiably curious, here's a brief description of how all these benefits come about. Not to be mistaken with metal spinning, flowforming is the application of uniform power compression to the outside diameter of a cylindrical component using a combination of axial and radial forces from three computer-numerically controlled (CNC), hydraulically driven rollers. As the metal compresses and lengthens onto the surface of the rotating mandrel, the grains take on a directional and spiral formation. The mandrel has the geometry of the internal shape of the finished component. Under controlled forces, the metal compresses above its yield strength point into the plastic (permanent) deformation zone, ultimately setting into the desired shape.

The origins of flowforming are believed to have been in Sweden in the 1950's. Since then, due to stringent dimensional and metallurgical control requirements in the aerospace and military industries, flowforming has been widely accepted as a process of choice in the fabrication of tubular-type components, such as missile casings, flight and launch motor housings, rockets, and cartridge cases. Today thin-walled tubes and closed-end cylinders are also used for chemical processing, cryogenic, filtration, food, medical, nuclear, pharmaceutical, semiconductor, and superconductor applications. For more information on flowformed products or to discuss how seamless zirconium and titanium tube, pipe, and other forms might fit your application, contact Dynamic Machine Works at 978-667-0202 or Oremet-Wah Chang at 541-967-6906.

A seamless titanium CP2 8 in. sch 40 pipe, 18 ft. long, flowformed from a 53-in. long preform.

Inside: Focus on Total Corrosion Solutions

Oremet-Wah Chang is pleased to present this special, Total Corrosion Solutions issue of Outlook. Total Corrosion Solutions encompasses the product lines and resources of OWC and its sister companies Allegheny Ludlum and Allvac. Together the three Allegheny Teledyne Companies produce a wide range of metals to solve nearly any corrosion challenge. This issue of Outlook contains technical articles from each company on topics ranging from specialty steels to titanium-niobium alloys. It also discusses joint trade shows we will participate in, includes an abstract from the upcoming Reactive Metals In Corrosive Applications Conference, as well as a new column, CPI News. We hope you enjoy this unique Outlook.

Thirty-three Papers Scheduled for Corrosive Applications Conference

Thirty-three technical papers are scheduled to be presented at the Reactive Metals in Corrosive Applications (RMCA) Conference, the second in a series of international corrosion-related meetings sponsored by Oremet-Wah Chang. The event is set for September 12-16, 1999 at Sunriver, Oregon.

The conference is divided in to eight technical sessions: Session I Plant Applications; Session II Materials Applications 1; Session III Fabrication Techniques and Advances; Session IV Cladding Technology; Session V Properties of Materials; Session VI Material Production Methods; Session VII Materials Applications 2; and Session VIII Corrosion Performance. Each session contains at least four presentations.

RMCA kicks off with an optional golf scramble Sunday, September 12, then launches into 3-1/2 days of presentations and discussion that will bring together pulp and paper, chemical and mineral processing, as well as others whose jobs pit them against corrosion. The event also includes an exhibition hall, luncheons, and evening receptions. It should prove to be a very productive, interactive conference.

For a brochure with a detailed list of papers and a registration form, contact Conference Secretary, Sheryl Renzoni at 541-926-4211 ext: 6280. Sign up soon as space is limited and will be filled on a first-come, first-served basis. We look forward to seeing you in Sunriver this fall!

Ti-45Nb: A Material of Construction for Wet Oxidation Processes

Reactive Metals in Corrosive Applications Conference Abstract

Andreas Daunmeyer of Bertrams AG submitted the following abstract for a paper he will deliver at the Reactive Metals in Corrosive Applications Conference this fall at Sunriver, Oregon. Mr. Daunmeyer will deliver his presentation during the Plant Applications Session on Monday, September 13, 1999.

Wet oxidation is often used in the area of wastewater technology to pre-treat non-biodegradable wastewater prior to biological treatment systems. Such systems operate at elevated temperatures (<300°C) and pressures (<180 bar). The most common wet oxidation systems are working at low pH-values, using air or pure oxygen as the oxidant. The operational parameters and the presence of additional corrosive compounds in the wastewater, like Cl and F, complicate the selection of construction materials.

One material for wet oxidation processes that may work is titanium and its alloys. However, titanium could ignite spontaneously at room temperature in the presence of pure oxygen at pressures of approximately 25 bars (350 psi). The wet oxidation process, LOPROX^®, is working at temperatures <200°C and pressures <20 bars with pure oxygen and, therefore, in a very critical area regarding ignition of titanium.

To minimize the chance of ignition, the titanium-clad reactor is liquid-filled. The oxygen is injected via a two-phase nozzle at the bottom of the reactor. These oxygen injectors are the most critical part in the LOPROX system, as they are exposed to pure oxygen on one side and in direct contact with the hot reactor and the corrosive waste on the other. Materials selected for the oxygen injectors must therefore address both corrosion resistance and oxygen compatibility at the operating temperatures and pressures.

Bertrams AG considered several materials in designing injectors for a project. Commercially pure titanium (Grade 2) was rejected as a possible injector material because, in the given system parameters, it provides no ignition resistance. Materials like Hastelloy^® have proven useful due to their excellent corrosion and ignition resistance in many environments; however, in the presence of chlorides, the susceptibility to pitting and crevice corrosion limit the application of these alloys. As an alternative to Hastelloy injectors, tantalum was considered, but proved an uneconomical choice.

A solution was found in the niobium-containing titanium alloy, Ti-45Nb (55% titanium and 45% niobium). Niobium is corrosion resistant and also ignition resistant in oxygen environments. Therefore, alloying niobium with titanium should yield an alloy that is useful in highly oxidizing corrosive environments. It is known that niobium has a substantially low heat of combustion and a high thermal conductivity. Both parameters are very important for ignition resistance.

The combination of corrosion and ignition resistance of Ti-45Nb in the highly oxidizing environments present in LOPROX systems have solved the material selection issues for oxygen injectors.

Look for more Reactive Metals in Corrosive Applications Conference abstracts in coming Outlooks. For more information on the event, contact Conference Secretary, Sheryl Renzoni at 541-926-4211 ext: 6280.

Allegheny Teledyne Companies Offer Total Corrosion Solutions at NACE and NY Chem Shows

Allegheny Ludlum, Allvac, and Oremet-Wah Chang, all Allegheny Teledyne Companies, are joining together at NACE and the New York Chem Show this year as the Total Corrosion Solutions Team.

When the three Allegheny Teledyne Companies combine resources and capabilities, they truly do offer total corrosion solutions. Consider that Allegheny Ludlum produces a wide range of alloys, from tough stainless steels to high tech alloys to titanium and titanium base alloys. Then there is Allvac, which makes a variety of corrosion-resistant nickel- and cobalt-base alloys as well as an extensive line of titanium and titanium-base alloys. Oremet-Wah Chang rounds out the team offering its severe-environment-tested line of titanium, Zircadyne^® Zirconium, and niobium products. It's a one-stop metals shop!

You'll find Total Corrosion Solutions at booth #355 at NACE and booth//2663 at the New York Chem Show. Qualified technical personnel will be on-hand to answer visitors' questions on corrosion resistant materials, potential applications, as well as other topics. All of this will be packaged in a brand new tri-company exhibit that features a 16-foot video tower, a you've-got-to-see-it-to-believe-it stainless steel centerpiece, a product display, and more. We look forward to meeting you at both shows in 1999!

Stainless Steels for Concentrated HNO₃ Service

by Ron Polinski, Allegheny Ludlum, an Allegheny Teledyne Company

Within the past two years, Allegheny Ludlum began commercial production of high silicon stainless steels for service in concentrated nitric acid (90% and above).

Allegheny Ludlum can produce grades AL-610 and AL-611 alloys in sheet, strip, or plate, and the alloys have been successfully manufactured as welded tubing. The ASTM chemical composition limits that apply to AL-610 and AL-611 alloys are shown in Table 1.

Commodity grade stainless steels such as Type 304L have been used at low temperatures in nitric acid concentrations of up to 65%. Above 65%, however, the corrosion rate of 304L begins to increase rapidly. On the contrary, the corrosion rates of AL-610 and AL-611 are high at weak and intermediate concentrations and begin to drop rapidly in very concentrated nitric acid solutions. The relative performance of each of the materials is depicted in Figure 1.

Although the alloys were originally developed some 20 years ago, Allegheny Ludlum is the only company in North America that produces these alloys. The alloys are covered by ASTM specifications (A240 and others) and ASME code cases 1953 and 2125 for AL-610 and AL-611 material, respectively.

Figure 1 Relative Corrosion Rates of Type 304L, AL-610, and AL-611 Alloy in Nitric Acid

Table 1 ASTM Chemical Composition Limits of AL-610 and AL-611 Alloy

While AL-610 and AL-611 alloys are produced within the chemistry limits specified by ASTM and ASME, the material is vacuum melted to achieve very low levels of carbon and nitrogen. The carbon levels of the heats produced by Allegheny Ludlum have had carbon levels typically about one-half (or less) of the specified maximum, and nitrogen has been held to similar levels. Corrosion testing has confirmed that these low levels of carbon and nitrogen result in significantly lower corrosion rates in concentrated nitric acid versus levels that are closer to the ASTM maximums.

Allvac is currently directing product development of weld wire with the same levels of carbon and nitrogen to allow fabricators the opportunity to optimize the corrosion resistance of welds. The weld wire should be available very soon.

Some companies are currently considering the replacement of aluminum 3003 tanks and piping with high silicon Allegheny Ludlum stainless steel. Reported advantages include superior corrosion resistance, higher strength and fewer fabrication concerns.

The addition of AL-610 and AL-611 stainless steels to the Allegheny Ludlum product line is another example of how Allegheny Teledyne strives to offer the most diverse range of products to best serve your needs. Allegheny Ludlum, Allvac, and Oremet-Wah Chang are Allegheny Teledyne Companies. For additional information on the alloys, contact Ron Polinski at 724-226-5079.

High Purity 316L Stainless Steel for Semiconductor Gas Distribution Systems

by Michael Antony and Tucker Redford, Allvac, an Allegheny Teledyne Company

Stainless steels are so widely used and inexpensive that at first glance they seem to have no glamour. Compared to the exotic nickel-base superalloys used in jet engines and the rare earth alloys used in superconductors, stainless steels can appear low-tech. However, some of the most advanced high-tech applications in the semiconductor industry rely heavily on the unique chemical and physical properties of 316L stainless steel.

Allvac has been double vacuum melting 316L stainless steel for more than 25 years. Whether for nuclear, chemical, or biomedical applications, the alloy and melt process are by no means new. However, by applying proprietary high purity melt technologies originally developed for aerospace, Allvac has substantially improved the performance of a relatively common stainless steel. This is a big improvement for a big market. Globally, the semiconductor market is estimated to be $50 billion...and growing!

This growth in the microelectronics industry is directly related to a decrease in manufacturing cost per electronic function. The consumer realizes this through lower cost computers with greater memory. The key to cost reduction is the shrinkage of feature sizes in integrated circuits. Current technology allows feature sizes of 0.5 microns, while future sizes are expected to reach 0.1 microns (1/500 of a human hair). At these levels, dust particles can entirely block several circuit paths and render a semiconductor chip useless. Obviously, 0.1 microns can only be achieved in ultra clean environments, and that requires components manufactured from high purity materials.

Semiconductor fabrication facilities, or "Fabs," require tubes, fittings, regulators, and valves to deliver bulk and specialty gases. In the most critical applications, the gas delivery system carries highly toxic and pyrophoric gases. The surfaces of gas delivery system components that are in contact with the process gases must be smooth, defect-free, clean and passive in order to minimize the potential for contamination of these gases. The exposed surfaces of the tubing, fittings, and valves are therefore electropolished and Cr-passivated. Electropolishing completely removes all traces of worked metal and smoothes the surface to a mirror-like finish. Cr-passivation is used to produce a continuous layer of Cr₂ 0₃. Properly performed, the completed process produces a surface that resists corrosion and prevents the adsorption of moisture.

Surface defects as small as a few microns can act as sites for water adsorption on the surfaces of components exposed to process gases. Moisture is a primary concern since the halogen gases, such as hydrogen chloride or hydrogen bromide, will corrode stainless steel when moisture levels exceed only a few PPM. Corrosion generally results in corrosion scale, which can enter the gas stream and damage any number of semiconductor chips or circuits. In the most dangerous case, corrosion might progress through the thin wall of a valve or fitting, and toxic gases like arsine and phosphine can enter a fabrication clean room.

Considering the critical nature of this industry's requirements, there is a temptation to apply exotic materials, like the pure nickel grades or titanium. After all, there are a variety of materials that could provide better corrosion resistance and cleanliness than 316L stainless steel. However, the semiconductor industry changes so quickly, the average life of a gas delivery system is just two to three years! With such a short life span, systems fabricated with more expensive materials could never achieve a satisfactory return. When considering performance, material cost, and fabrication costs, the optimum solution is ultra high purity 316L stainless steel.

Ultra high purity describes a condition wherein the metal is free from non-metallic inclusions. It is well known that nonmetallic inclusions in standard 316L act as sites for pitting defects during electropolishing. Ultra high purity 316L will offer defect levels acceptable for semiconductor gas delivery systems. Commercially available 316L, however, would not be free from inclusions because of the difficulty in totally eliminating oxygen, sulfur, and nitrogen. Vacuum melting offers the best control of non-metallic inclusions, and vacuum melting is the method most commonly chosen for semiconductor gas delivery components. Vacuum melting is Allvac's forte. Allvac is a worldwide leader in vacuum melting technology, and one of only a few companies capable of producing ultra high purity 316L stainless steel.

Two consecutive vacuum melting steps are used to produce ultra high purity 316L. The first step involves melting raw materials and casting an electrode. The second step involves remelting the electrode at a controlled melt rate. The most common methods for melting ultra high purity 316L are Vacuum Induction Melting (VIM) + Vacuum Arc Remelting (VAR). VIM produces the exact chemistry required and refines the metal. VAR ensures that the ingot is sound as well as chemically and physically homogenous. In addition, a small amount of refining or inclusion removal occurs during VAR.

The standard method for measuring steel cleanliness is examination of steel samples under a light microscope at 100 times magnification. Though this method provides an adequate measurement, it is not sensitive to minor changes in cleanliness, particularly for high purity alloys. The standard method for measuring cleanliness of ultra high purity 316L uses a scanning electron microscope (SEM) and magnifications of 3,000 times. The SEM is used to examine electropolished surfaces for roughness and defects that are too fine to be seen by light microscopy. The surface flaws found are generally the result of excessive inclusion defects in the material or improper finishing and electropolishing.

Allvac Ultra High Purity 316L stainless steel offers excellent surface quality after electropolishing. Independent evaluations of surface smoothness and defects after electropolishing have shown Allvac Ultra High Purity 316L to be incredibly clean. In fact, one equipment manufacturer stated Allvac's 316L to be the cleanest material they had ever tested. Such evaluations indicate that Allvac's Ultra High Purity 316L can indeed meet the demanding requirements of the semiconductor industry. And, with the support of Allegheny Ludlum, this level of cleanliness can be produced in most every product form: forging billet, extrusion billet, forging bar, annealed machining bar, cold reduced bar, plate, sheet, and strip coil.

At Allvac, several research projects are currently focused on understanding non-metallic inclusions and further improving metal cleanliness. The small size of these inclusions makes continuous improvement a formidable goal. Allvac is constantly striving to improve metal cleanliness - in all products - through better process control and higher quality raw materials. Like the inclusions, the improvements will most likely be small. The long-term gains, however, will benefit the world.

For more information on Allvac and its alloys, call (704) 289-4511 or fax (704) 226-0446.

LaRoche Industries Inc. will host the 1999 Nitric Acid Producers Meeting at the Opryland Hotel in Nashville, Tennessee, June 28-30. Oremet-Wah Chang and a contingent of suppliers to the chemical process industries will be on hand to co-host a golf scramble and awards reception (June 28), a luncheon (June 29), and evening hospitality events (June 28 and 29). Most importantly, the exhibitor group will offer solutions to challenges facing plant operators and engineers.

For more information about attending the meeting (including registration), contact LaRoche's David Kelley at 256-359-7272 or Jennifer Sprague at 256-359-7211. LaRoche is also organizing entertainment events for the weekend preceding the conference (June 26 and 27) again, contact Mr. Kelley or Ms. Sprague for more information.

The exhibitor hall is currently sold out. To be put on a waiting list, contact Oremet-Wah Chang's Sheryl Renzoni at 541-926-4211 ext: 6280.

Finally, to make reservations at the Opryland Hotel, call 615-883-2211 and let them know you are with the Nitric Acid Producers Meeting group. We look forward to seeing you in Music City this summer?

The Mineral Processing Industry has a number of shows coming up this Spring. Oremet-Wah Chang will be offering its corrosion-resistant metals at three events in May alone. The month kicks off with the CIM Tradex '99 in Calgary, Alberta May 2-5. OWC will provide information on its corrosion /erosion resistant zirconium, titanium, and titanium-niobium products at booth #650. For more information on CIM Tradex '99, call 514-939-2710.

The busy month also includes a meeting in Perth, Australia. OWC will take part in the Alta Show, May 10-12, 1999 at the Hotel Rendezvous in Perth. Staff with a strong technical background will be in booth #2 to answer attendees’ questions and offer solutions for corrosion/erosion and other problems related to tough mineral processing environments. For information on the Alta Conference, call 61 3 98779335.

In addition, OWC will participate in the Randol Gold and Silver Forum '99. The Randol event will be held May 11-14, 1999 at the Hyatt Regency Denver Downtown. Again, the company will use the Forum to discuss its corrosion/erosion-resistant alloys like Ti-45Nb, which the industry has found particularly useful in pressure oxidation applications, where.... ignition is a concern. OWC will be in booth #25. For more information on the Randol Gold and Silver Forum, please contact Randol at 303-526-1626. We look forward to meeting with you at these excellent events!

Allvac, Allvac-SMP (UK), Allegheny Ludlum, and Oremet-Wah Chang will team up at the 43rd Paris Air Show, June 13-20, 1999. Their joint exhibit will be at Stand #D2 in the USA National Pavilion. These Allegheny Teledyne Companies manufacture a wide range of high performance metals, including stainless steels, specialty steels, superalloys, nickel and cobalt base alloys, titanium, and niobium for aerospace applications. Please stop by Stand #D2 to discuss your aerospace materials needs, and to obtain assistance from ATI's High Performance Metals specialists. We look forward to seeing you in Paris..

Q&A:

Ti-45Hb Corrosion Resistance

Laboratory since 1997, submitted this issue's Q&A, which focuses on Titanium-45Niobium's corrosion resistance. Mr. Tosdale has an M.S. in Metallurgy from Iowa State University. He has worked in the Metals Industry since 1966.

Question:

The 11-45% Nb alloy has been used successfully in autoclaves for leaching ores in a high oxygen pressure process because of its high resistance to ignition, is it useful as a corrosion resistant material in other media and applications?

Answer:

Previous issues of the Outlook (Vol. 13 No. 3, Vol. 14 No. 4 and Vol. 15 No. 2) addressed the favorable ignition resistance of the Ti-45%Nb (TiNb) alloy in pure oxygen. The original application for TiNb in the corrosion industry involved pressure oxidation of a sulfide ore to recover gold. TiNb performed significantly better than the previously used titanium and resulted in a much safer operation. In addition, TiNb was found to be very resistant to corrosion in the oxidizing sulfuric media in the autoclave based on results from test coupons placed in the vapor space of an operating autoclave. A nil corrosion rate was observed even after 180 days of exposure!

As shown in the following table, the strengths of TiNb as a material of construction are its low density and high strength along with superior ignition resistance in oxygen. It suffers from a lower thermal conductivity and modulus of elasticity and increased thermal expansion. Where heat transfer is important, such as heat exchangers, the lower thermal conductivity will partially offset the gains made in construction costs by the low density and high strength.

Since 1990, when the pressure oxidation application was first developed, Oremet-Wah Chang has measured TiNb's resistance to corrosion in various media. The alloying of titanium and niobium should build on the strengths of each constituent. Titanium is noted for its corrosion resistance in oxidizing environments. Its breakdown potential in seawater is high, at 9 volts, so seawater applications comprise a major market for titanium. Niobium has corrosion resistance similar to tantalum in many media. It also is very resistant in oxidizing acid conditions, and can also be useful in mildly reducing media. The niobium oxide film has a high dielectric property and very high breakdown potentials (115 volts in seawater). In reducing media, such as HCl, and dilute sulfuric acid, niobium is less resistant than tantalum. The addition of oxidizing species or an anodic potential in these acids improves niobium's resistance to corrosion. The rest of this answer addresses TiNb's resistance in various common media and compares it to titanium and niobium.

Sulfuric Acid - Titanium is not very resistant to sulfuric acid above about 25% concentration and room temperature. At the solution boiling point, titanium is not recommended for service for all concentrations. Niobium is resistant to sulfuric acid to 98% when the temperature is below about 50°C and may have limited service capability at concentrations less than 50% if the temperature exceeds about 50°C. At 10% sulfuric acid concentration in a boiling solution (123°C), the corrosion rates tested at Oremet-Wah Chang for Ti, Nb and TiNb all exceeded 140 mpy. Open circuit potentials were measured in this 10% solution at room temperature with TiNb's potential 67 mv higher than titanium and 75 mv lower than niobium. This supports the findings of the immersion tests, where TiNb's corrosion rate was similar to niobium's and lower than titanium's.

Hydrochloric Acid - Niobium is very resistant to boiling HCl at concentrations less than 20%. It can withstand concentrated hydrochloric acid if the solution is kept near room temperature. Titanium has little resistance to HCl above about 5 to 10% concentration, even near room temperature. For both niobium and titanium, the resistance to HCl is improved if oxidizing conditions are present to help repassivate the metal surface. TiNb was tested in a 20% solution with and without ferric at 100°C where the corrosion rates exceeded 200 mpy in both cases. We measured the corrosion rate of TiNb in a 37% solution at 60°C to be 1.8 mpy for HCl and 76 mpy for HCl with about 1% ferric chloride added. This may be due to the presence of other impurities in these process solutions. We have recently tested TiNb for its placement in the galvanic series for seawater. The galvanic potential for TiNb was identical to titanium and only 40 mv below niobium.

Nitric Acid - Niobium is very resistant to HNO₃ at concentrations to 90% to the boiling point. Above 90%, the temperature is limited to 60°C for adequate resistance. Titanium resists corrosion in solutions up to about 70% concentration at near boiling conditions. For temperatures above boiling and concentrations above 70%, titanium is not recommended.

We have tested TiNb in 40% HNO₃ with and without 5% NaCl and measured corrosion rates less than 5 mpy with NaCl at 150°C and less than 7 mpy without the NaCl at 105°C. We do not have corrosion data for TiNb in nitric acid above 40% concentrations. We did electrochemical testing on niobium and TiNb in HNO₃ + HCl and HNO₃ + H₂SO₄ solutions at 90°C, which showed the breakdown potential for TiNb to be greater than 3 volts, the same as niobium. Here again, these results support the immersion testing results.

6% Sodium Hypochlorite - At room temperature, all three metals show no corrosion. At 50°C, the measured rate in niobium was 31 mpy, in titanium was less than 5 mpy and in TiNb was less than 1 mpy.

Chlorine Dioxide - Corrosion of TiNb in ClO₂ was evaluated by immersion and electrochemical tests. TiNb is highly suitable for handling chlorine dioxide solutions at all concentrations. Immersion tests at room temperature showed a nil rate for TiNb and <1 mpy for titanium. For TiNb, pickled coupons performed better than mill condition surfaces. The breakdown potential for the pickled coupons was 1.1 volts higher than the mill condition coupons.

Summary - In sulfuric acid, the TiNb alloy may provide a slight improvement in resistance over titanium and offer resistance similar to niobium. The corrosion resistance of the TiNb alloy in HCl is somewhat better than titanium and similar to niobium at concentrations less than about 20%. TiNb may even raise the upper concentration limit above that of niobium. We have not done enough testing in nitric acid to establish TiNb's resistance profile. In sodium hypochlorite and chlorine dioxide, TiNb does not show a significant improvement over titanium. We will continue to fill in the holes in the resistance profile of TiNb. For more information or to ask about our corrosion lab services, contact Jack Tosdale at 541-917-6777.

OWC Sales Force Makes Strategic Moves

Oremet-Wah Chang, an Allegheny Teledyne Company, is pleased to announce a few important changes in its Sales Organization. In April, Mr. Barry Valder was named Business Development Manager, Niobium/Superconductivity. Mr. Valder started with Wah Chang in 1978 in its Purchasing Department.

He joined Sales in 1981 and has worked with zirconium, niobium, and hafnium product lines. Most recently he was Business Development Manager, Nuclear. Mr. Valder now reports to Mr. Gary Kneisel, Director of Sales.

In February, Mr. William Budd joined Oremet-Wah Chang's Corrosion Services Group. Mr. Budd has 24 years' experience in metals sales, starting his career with Titanium Industries, then working in metal sales at Oremet for 12 years. He was most recently Castings Sales Manager for Oremet. Mr. Budd now reports to Mr. Doug Brenizer, Business Development Director, Corrosion Services.

In January, Mr. Robert Marsh also joined the Corrosion Services Group. Mr. Marsh has 24 years' experience with metals production and sales. He began his career at Wah Chang working in zirconium production and, over many years, has also built in-depth knowledge of the company's niobium and titanium product lines. Mr. Marsh reports to Mr. Doug Brenizer, Business Development Director, Corrosion Services.

For further information or to purchase our metal products, contact Oremet-Wah Chang's Sales Department at 541-967-6977.

News in Review

by Molly Burger

Kvaerner was awarded a $60 million contract to construct a sulfuric acid plant for Codelco in Chile. Construction will begin in June 1999 and the plant will come on line in January of 2001. London (AFX)

Krupp Uhde was awarded a contract to build Egyptian Fertilizer Co.'s 1,200 t/d ammonia and 1,925 t/d urea complex. The ammonia plant will use Krupp technology, and the Urea plant will use Stamicarbon and Norsk Hydro technology. Fertilizer International 1/1/99

Sterling Chemicals and BP Amoco announced a project to increase capacity at Sterling's Texas City acetic acid plant by 25% to almost a billion pounds per year. This new project will employ BP Amoco's new process and catalyst technology. Chemical and Engineering News 2/22/99

BHP of Australia is still interested in going ahead with the ammonia/urea project at Phu My, Vietnam, even though the project has been delayed by feedstock gas price negotiations. The project should come on line in 2001/2002. Nitrogen and Methanol 1/31/99

Two new nitric acid projects are in the study phase, a 130,000 t/y plant in Shanghai, China by BASF and its Chinese partners and a 100,000 t/y in the UAE (United Arab Emeritas) by GOIC and partners. European Chemical News 3/15/99