In this ‘insights from industry’ interview, Dr Yuri Zhuk, Technical Director at Hardide Coatings Ltd., talks to AZoM regarding the importance of seal reliability, especially in adverse conditions.

GT: Could you please provide a brief overview of Hardide and some of the new coatings that Hardide is producing?

YZ: Hardide Coatings Ltd, an advanced surface coating company, is a leading innovator in the development and production of metal surface coatings based on Tungsten Carbide. The company is currently producing the Hardide range of chemical vapour deposition (CVD) tungsten carbide / tungsten hard coatings, which have exciting and wide-ranging applications in industries including oil and gas, valves, pumps, aerospace and advanced engineering..

GT: What are the primary applications of these coatings?

YZ: Applications where wear, erosion, corrosion or chemically aggressive media cause component and tool or equipment downtime, failure or loss of performance. The coatings are hard, tough, flexible, ductile and impact resistant and can coat internal surfaces and complex geometries so can be used in many applications where traditional hard coatings are not suitable.

An important application of these CVD coatings is their use on mechanical seals for heavy-duty rotating equipment.

Rotating equipment, including turbines, compressors and pumps, use mechanical face seals to prevent leakage, whilst also excluding any abrasive media and lubricating the mechanical assemblies. The importance of seal reliability cannot be overstated when looking at overall equipment reliability, because seal failure results in the damage of costly equipment, and would also cause higher downtime costs.

GT: Which industries benefit from these coatings?

YZ: Primarily the oil, gas and chemical processing industries will benefit from Hardide’s CVD coatings for mechanical face seals. However, any industry that employs heavy-duty mechanical face seals will benefit, especially if these are employed in adverse conditions.. In particular, these coatings are used to make the ‘primary’ sealing surface durable and capable of resisting three-body abrasion, erosion and corrosion.

 GT: What materials are traditionally used on mechanical seals and what are the limitations of these?

YZ: Solid hard materials, such as ceramic, silicon carbide, or sintered tungsten carbide are frequently used. However, these materials have several significant limitations and disadvantages, which are listed below:

    They are brittle
    They are expensive and difficult to produce (especially if there are finer features included in the seal design)
    The thermal expansion properties of these materials can differ significantly from steel, leading to jamming with a change in temperature.

HVOF, plasma spray coatings (such as WC/Co), DLC and other PVD coatings are already used on mechanical seals. However, these are often not effective for heavy-duty seal applications. For example, WC/Co HVOF and plasma spray coatings contain hard WC grains in a soft cobalt binder. These coatings can become very rough in abrasive/corrosive environments due to the selective leaching or abrasion of the binder.

GT: How do the Hardide coatings address these common problems?

YZ: An even wear pattern is ensured by the uniform structure of Hardide coatings, so an optimum finish can last for longer without hard asperities forming. Both tungsten carbide and tungsten have excellent resistance to chemically aggressive/corrosive media, particularly acids. The coating might be further alloyed with small amounts of Fluorine or Fluorocarbons (as disclosed in Hardide patents), which can further enhance its mechanical properties.

An alternative approach is to manufacture the mechanical seal components out of steel and then coat with a hard coating. Using steel is beneficial for the following reasons:

    It is tough
    It is inexpensive
    It can lead to improved and larger ranges of seal design
    It is relatively easy to machine

GT: How does using CVD tungsten carbide coatings effect the lifespan of machinery?

YZ: It has been shown that the coatings can triple the operational life of critical parts in abrasive conditions. Mechanical face seals display similar, long-lasting results.

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There are fresh hopes Cornwall's mining industry could be revived.

Test drills for tin and tungsten near Callington and Indian Queens are expected to start this year.

Companies New Age Exploration Limited and Treliver Minerals have acquired the rights to carry explore deposits underneath Kelly Bray near Callington and Treliver Manor Farm near Indian Queens respectively.

Similar work searching for tin, copper and zinc has already been carried out at South Crofty Mine in Camborne.

Chris Rogers, Mining Consultant for Redruth-based firm Cornwall Consultants, said: "It's to do with the economic heritage of the county, and obviously the future possible employment and wealth that might come from mining these deposits locally, and the benefit to the local communities.

"Obviously if they did find things, they'd have to go through mining and planning leases. They'd have to look at environmental constraints, they'd have to look at processing constraints, and the general viability of the deposits in these areas."

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BERLIN - Whether it is its solidly high price per ounce or maybe even the end-of-year visit of Her Majesty, Elizabeth II, to view British gold reserves at the Bank of England, conspiracy theories are proliferating around gold – particularly as (or so rumor has it) some kilo bars appeared in Great Britain that were filled with virtually valueless wolfram.

Some insiders even believe that a large portion of Germany’s gold reserves are in fact gold-coated wolfram (tungsten) bars. The sheer values involved – a standard 12.44 kg gold bar is presently worth 500,000 euros – go a long way to explaining the stubborn attachment to theories such as these, the spread of which are aided considerably by the Internet, reports Die Welt.

The precious metal had another strong week, with gold's spot price closing Friday at $1,687 per ounce.

Eugen Weinberg, who heads commodities research at Germany’s Commerzbank, says that he is certain that – if indeed there are any tungsten-filled bars at all out there – the number of them is exceedingly small.

German theorists’ fears are particularly fueled by the fact that, according to the German Federal Bank itself, only part of German gold reserves are actually in Germany: the bank says that “a good two thirds” of the 3,396 ton German reserves worth 145 billion euros are not actually stocked inside the country.

Among the rumors accompanying the nearly two-year upward trend in gold prices is that key national treasuries – not least Fort Knox in the United States – have now actually been emptied out. Another fashionable conspiracy theory sees price manipulation of the precious metal by a powerful international elite that controls the market.

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Several business groups challenging new rules that require companies to disclose whether their products contain minerals blamed for fueling violence in Africa said Wednesday regulators hadn’t adequately analyzed the rules’ impact.

The groups said in court papers that the Securities and Exchange Commission had itself admitted it didn’t know if the rules would benefit the people of the Democratic Republic of the Congo and its surrounding region, the stated intent of Congress in creating the provision.

“Thus, the Commission violated its statutory obligations to apprise itself of the costs and benefits of the rule and the available regulatory alternatives before saddling U.S. public companies with billions of dollars in regulatory burdens,” the groups said. “This failure of analysis infects the entire rule.”

The U.S. Chamber of Commerce, the National Association of Manufacturers and the Business Roundtable asked the U.S. Court of Appeals for the District of Columbia Circuit to vacate the “conflict-mineral” rules in October. The groups fully explained their arguments for the first time on Wednesday in a 75-page brief.

UPDATE: John Nester, a spokesman for the SEC, defended the Commission’s analysis in an email.

“We believe our legal interpretation and economic analysis are sound, and we look forward to defending the rule that Congress directed us to write,” Nester said.

The “conflict minerals” rules, which were mandated by the 2010 Dodd-Frank financial overhaul, have been a source of friction between the SEC and companies ever since the law was passed. Under the current rules, U.S.-listed companies are required to disclose whether their products have been manufactured with any tantalum, tin, gold or tungsten used to finance violence in central Africa.

Companies have said the requirement would be burdensome and expensive. In August, the SEC estimated the rules would cost companies a total of $3 billion to $4 billion upfront to comply, plus more than $200 million a year. The SEC also estimated around 6,000 U.S. and foreign companies would have to comply with the conflict-minerals rules, affecting manufacturers of a range of products, including smartphones, light bulbs and footwear.

On Wednesday, the groups said that the SEC’s estimates are actually low, and that a financial burden of that size shouldn’t be imposed without determining whether the rules will yield any benefits. The SEC’s lack of analysis, according to the groups, violates the Administrative Procedure Act and the agency’s heightened obligation under the Securities Exchange Act of 1934 to analyze the economic impact of its rules.

The groups also argued that the rules violate companies’ First Amendment rights by compelling them to publicly state their products are “not DRC conflict free,” that is, they contain conflict minerals.

“Even worse, this compelled disclosure will frequently be false,” the groups argued. “Many of the companies forced to make it will not be manufacturing products containing minerals that funded armed groups. Rather, the companies will simply be unable to trace their supply chains to determine the minerals’ origins.”

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