Technics

Cost-Effective Diamond-Like Carbon Coating

Institute scientists have successfully demonstrated a diamond-like carbon (DLC) coating that promises to be comparable in cost to physical vapor deposition coatings. First developed during the early 1980s at A.E.A. Harwell in Britain, the DLC is produced at low temperatures using an ion beam-assisted deposition process and can cover areas up to several square feet. The Institute maintains a large ion beam facility dedicated to applied research and development and batch processing.

Diamond-like carbon films have many of the same properties of diamond films -- extremely low friction, high hardness, and chemical inertness -- but are less expensive. For many friction and wear applications, DLC is considered superior to polycrystalline diamond because very smooth coatings can be deposited. The DLC coating offered by SwRI has a coefficient of friction below 0.1 under dry sliding conditions even at high relative humidity. Adhesion of the DLC coating to steel and other metal surfaces, a problem for many DLC methods, is excellent when an SwRI-developed bond coat (patent pending) is used.

Applications of the DLC coating already demonstrated at SwRI include friction and wear coatings for engine components and mold release coatings for compression and injection molding of plastic and rubber products. Other promising applications are tools and dies, pump components, bearings, and gears.

Continuing Quest for a Cleaner Diesel

A successful international cooperative industry research program known as the Clean Heavy-Duty Diesel Engine (CHDDE I) project, initiated by SwRI in 1991 to develop a low emissions diesel engine to meet proposed U.S. emissions and efficiency standards for the year 2000, has been extended for an additional four years.

"In the second phase of the program, we will try to meet standards that go beyond industry targets proposed for the year 2004," says Daniel W. Stewart, manager of Engine Development and Controls in the SwRI Engine and Vehicle Research Department. "CHDDE II goals call for the reduction of exhaust emissions for nitrogen oxide to levels of less than 1.0 gm/hp-hr and for particulate matter to less than 0.035 gm/hp-hr.

"There will be some changes in the focus of our research," he adds. "Key technologies to be addressed during the CHDDE II program include the effects on fuel injectors of higher pressure, smaller nozzle openings, and rate controls. We will also study exhaust aftertreatment using passive particulate traps, evaluate fuel reformulation as well as the use of water/fuel emulsions controlled in real time, and investigate the effects of exhaust gas recirculation in diesels, a technology that is already well-established in gasoline engines." A homogeneous charged compression ignition combustion system operating on diesel fuel will also be investigated, and engine efficiency levels will be maintained at industry-proposed 1998 levels.

"We will also try to develop design alternatives and strategies to optimize the effective use of new design technologies derived from the program into various product lines suggested by participants," notes Stewart.

Engine firms participating in the program to date include Cummins Engine Company, Columbus, Indiana; DAF Trucks N.V., Eindhoven, Netherlands; Iveco, Arbon, Switzerland; Hino Motors, Ltd., Tokyo, Japan; Mack Trucks, Inc., Hagerstown, Maryland; Volvo Truck Corporation, Gšteborg, Sweden; John Deere, Waterloo, Iowa; and Detroit Diesel, Detroit, Michigan. Component suppliers include Garret Automotive, Torrance, California; Zexel Corporation, Saitama, Japan; and Lucas Electronics, Gillingham, United Kingdom. Membership in the program remains open.

Cost-Effective Corrosion Detection

Southwest Research Institute engineers have launched a multiyear cooperative industry research program to develop a cost-effective and efficient field instrument to detect corrosion in insulated pipes. The instrumentation under evaluation relies on magnetostrictive sensor (MsS®) technology.

Corrosion of insulated steel pipes can cause safety and operational concerns, and the problem has become more frequent as the piping infrastructures age. Inspection of these pipes requires equipment shutdown and insulation removal, both of which are time-consuming and expensive.

"Defects in pipes such as corrosion or cracking are identified using MsS instruments that launch elastic waves in frequencies up to a few hundred kHz and detect the signals reflected from any defects," says Dr. Hegeon Kwun, a senior research scientist in the Institute's Nondestructive Evaluation Science and Technology Division and manager of the cooperative program. "The entire cross section of the pipe wall can be inspected for inside and outside surface flaws. A section of piping up to 100 feet long can be surveyed from a single sensor location, providing a fast and efficient means of 100-percent volumetric inspection."

In the first phase of the joint industry program, MsS sensors are being used to test various grades of ferromagnetic piping materials up to 16 inches in diameter, at temperatures ranging from -48 to 450 degrees Celsius, and at operating pressures up to 1,500 psi. The results of the first phase will be used to define specifications for the field instrument to be developed in subsequent program phases, which will involve specific instrument design, field trials, and commercialization.

Current members of the consortium include Chevron Research and Technology, Richmond, California; CTI Alaska, Inc., Anchorage, Alaska; the Electric Power Research Institute, Palo Alto, California; TEAM, Inc., Alvin, Texas; the Texaco Group, Inc., Port Arthur, Texas; the CXR Company, Ltd., Hiroshima, Japan; and the Tokyo Gas Company, Ltd., Tokyo, Japan.

All research information shared between members is confidential and proprietary. Program participants will derive the following benefits:

  • They can accelerate the commercialization of the technology for oil and chemical industry applications.
  • They can influence the directions, scope, and priorities of the program through active participation on the Technical Advisory Committee.
  • Operating companies will secure royalty-free rights to use SwRI patented technology (U.S. Patents No. 5,456,113 and 5,457,994) in plants worldwide.
  • Service companies can recover their membership fees through royalties paid to SwRI for the use of the patented technology.

Ion Beam Surface Modification Facility Upgrade

The Institute has added a 120-kilovolt plasma bucket ion source to its ion beam surface modification facility. The addition makes SwRI's ion beam facility the largest and most versatile commercial facility in North America for nitrogen ion implantation. Unlike conventional techniques such as plating or vapor deposition in which a coating is applied to the surface of a material, ion implantation bombards the surface with energetic atoms. Because ion implantation is not a coating process, there is no increased dimension, no surface change, and no thermal deformation of the workpiece. Ion implantation can be used to harden the metal surfaces of tools such as stamping dies, knives, and molds.

The plasma bucket source allows Institute scientists to carry out nitrogen ion implantation over large areas. "We can treat surfaces up to four square feet or as many as 100 tools per batch depending on their size," explains Dr. James Arps, a research scientist in SwRI's Materials and Structures Division.

The Institute added the plasma bucket ion source as part of a pilot program to demonstrate to industry that ion implantation and other surface modification processes are viable and economical on a large scale.

"We hope to show that what we do in our facility on a small scale can be extrapolated to industry for a wide range of industrial tools and equipment," Arps notes.

Published in the Fall 1996 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.

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