A laser cladding process has been developed and is now in production for the cladding of new aircraft carrier catapult components. The Service Life Extension program (SLEP) Office of Naval Sea Systems Command (NavSea)...
A laser cladding process has been developed and is now in production for the cladding of new aircraft carrier catapult components. The Service Life Extension program (SLEP) Office of Naval Sea Systems Command (NavSea) suggested that this process be utilized for the refurbishment of catapult tracks. Early experiments were conducted by the Naval Surface Warfare center in conjunction with the IIT Research Institute. The program was then transitioned to the Applied Research Laboratory, Pennsylvania state University (ARL Penn state) under the sponsorship of the Naval Air Systems Command (NavAir)/Navy MANTECH program, thus providing an effective solution to a NavSea/NavAir interface hardware problem. ARL Penn state was responsible for the production and evaluation of six laser clad aircraft carrier catapult tracks as part of a program sponsored and funded by NavAir Code 5512. Six catapult tracks that had been taken out of service because of excessive wear were laser clad at the Westinghouse Electric Research and Development center (Now ''science and Technology center'') for ARL Penn state. The composition of the clads was Inconel 625, Stellite 6/Stainless Steel 304, and Ferrelium 255. The tracks were machined and installed on the USS Constellation. Wear measurements were taken for the laser clad tracks and standard tracks ahead and behind the clad tracks. After 7,161 launches, the tracks were removed and returned to ARL Penn state for evaluation. The evaluation indicated that impact damage was observed on one track. No additional defects related to operations were found. Wear data indicated that the wear rate for it was 25%-50% less than non-clad. The results indicated that rejectable tracks (and one piece trough covers) could be successfully laser clad for extended operating life at acceptable costs. With emphasis for the future on a more affordable Navy, the need for viable refurbishment processes will be necessary for extending life and performance for the 21st century
作者：
MITTLEMAN, JSWAN, LJohn Mittleman:is a mechanical engineer at the Naval Surface Warfare Center
Dahlgren Division Coastal Systems Station in Panama City Florida. His Primary Responsibilities are in the development of underwater nondestructive testing equipment for use by fleet divers and inspectors. He also performs research in the characterization of metal microstructure through ultrasonic scattering measurements. Mr. Mittleman received his BS from Cornell University in 1969 and science master's in ocean engineering from the Massachusetts Institute of Technology in 1970. His research currently supports doctoral studies with Iowa State University. Mr. Mittleman received the American Society of Naval Engineer's Solberg Award in 1981 for his contributions to underwater ship hull inspection. Mr. Mittleman is a member of ASNE
ASNT ASTM IoD Sigma Xi Tau Beta Pi and Phi Kappa Phi. Lisa Swan:is a mechanical engineer at the Naval Surface Warfare Center in Panama City
Florida. She is involved in nondestructive testing engineering primarily in the underwater arena. Ms. Swan holds a bachelor of science in materials engineering from North Carolina State University. She is a graduate of the Federal Women's Executive Leadership Program. Ms. Swan is a member of ASNT.
Significant progress has been made in making underwater ultrasonic thickness gauging and magnetic particle inspections available to the fleet. Under sponsorship from the Naval Sea Systems Command, Director of Ocean En...
Significant progress has been made in making underwater ultrasonic thickness gauging and magnetic particle inspections available to the fleet. Under sponsorship from the Naval Sea Systems Command, Director of Ocean engineering, Underwater Ship Husbandry Division (NavSea 00C5), the Coastal Systems Station has developed complete hardware packages supporting these two nondestructive test methods, and has introduced them to military inspectors at a shore intermediate maintenance activity, a destroyer tender, and a naval shipyard. Performance trials conducted prior to taking the systems to the field have been accepted by NavSea, Ships' Concepts Group, materials Subgroup, Metals Division (NavSea 5142) as evidence that these inspections can reliably be performed underwater. Avenues for certifying specially trained divers and inspectors are being developed;for the first time the Navy will have all of the elements in place for underwater inspections satisfying the requirements of Mil-Std-271 (Requirements for Nondestructive Testing Methods) and the Naval Ships' Technical Manual Chapter 074. Underwater ultrasonic thickness gauging has also been slated for use in the fleet, as data from laboratory and field trials have consistently shown that reliable results can be obtained by a team comprising a certified topside inspector and a diver. In tests performed at the Ship Repair Facility (SRF), Yokosuka, underwater readings were compared to those taken in dry dock by SRF inspectors, and independently by contract inspectors. On the basis of approximately 800 locations, differences between the data sets were found to be randomly distributed, with a standard deviation on the order of 0.02''. This level of accuracy is largely sufficient to distinguish plate which will need replacement during overhaul, or plate which is thick enough to weld on.
We show that the principal axes for absorption and cmission in the monoclinic crystals Nd doped BaY2F8 and La2Bc2O5 do not coincide with cither the crystallography axes or the axes of the index elipsoid, and also that...
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Thin films of titanium, platinum, and hafnium were deposited on single crystal n-type, (0001) 6H-SiC at room temperature in UHV. Microstructure and chemistry of their interfaces were analyzed by high spatial resolutio...
Thin films of titanium, platinum, and hafnium were deposited on single crystal n-type, (0001) 6H-SiC at room temperature in UHV. Microstructure and chemistry of their interfaces were analyzed by high spatial resolution TEM imaging and spectroscopy. Ti5Si3 and TiC were the two phases found in the reaction zone of Ti/SiC specimens annealed at 700°C. A carbon-containing amorphous layer formed between Pt and SiC when the annealing temperature went up to 750°C. There was no apparent reaction zone in Hf/SiC specimens annealed at 700°C for 60 min.. The change of electrical properties of metal/6H-SiC devices was attributed to these new product phases.
Cr3+:LiSrGaF6 is a new promising candidate for flash-lamp pumped laser due to very low scattering loss. We will discuss our work on the material preparation and crystal growth of large transparent boules of Cr3+ :LiSr...
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Transparent and uniform thin films of crystalline KNbO3 were synthesized on different substrates such as SrTiO3, ZrO2, MgO and Pt by the dip-coating method using a double alkoxides solution. The film was epitaxially c...
Transparent and uniform thin films of crystalline KNbO3 were synthesized on different substrates such as SrTiO3, ZrO2, MgO and Pt by the dip-coating method using a double alkoxides solution. The film was epitaxially crystallized at the temperature around 750°C for 3 hours in air on SrTiO3 single crystal substrate. The structure of the films has been studied with X-ray and electron diffraction, and transmission electron microscopy. Different molar ratios of 2-ethylhexanoic acid (2EHA) to alkoxides were applied to control the hydrolysis rate of the sol-gel solution. Dense films were obtained after modification of the alkoxides solution.
We present results on the synthesis of a-C:N films deposited by pulsed excimer laser ablation of graphite in a nitrogen gas ambient. Analysis with RBS and forward recoil spectrometry show that the films are hydrogen-f...
We present results on the synthesis of a-C:N films deposited by pulsed excimer laser ablation of graphite in a nitrogen gas ambient. Analysis with RBS and forward recoil spectrometry show that the films are hydrogen-free and nitrogen can be incorporated upto 40% by varying the nitrogen gas pressure. Electron microscopy has identified these films to be amorphous. Raman spectroscopy, infrared spectroscopy, and electron energy loss spectroscopy have revealed carbon-nitrogen bonding structures. Compared to a-diamond films prepared by the same technique, the C:N films still possess the properties of high mechanical hardness, chemically inertness and good wear resistance, but incorporation of nitrogen into the films generally degrades their diamondlike properties. The results suggest that nitrogen doping effect is resulted in the films under the present process, instead of carbon-nitrogen compound formation.
Small crystallites of CdTe have been produced using a new solution synthetic method. In this technique, Cdl2 and Na2Te are each dissolved separately in methanol before rapid mixing. The product of this reaction is pur...
Small crystallites of CdTe have been produced using a new solution synthetic method. In this technique, Cdl2 and Na2Te are each dissolved separately in methanol before rapid mixing. The product of this reaction is pure, stoichiometric CdTe with interesting electronic and optical properties. Photoluminescence studies of this material show a blue shift due to the quantum confinement, indicating the presence of small crystallites. Transmission electron microscopy confirms the presence of nanocrystals. Reaction temperature and processing conditions can be varied to change the crystallite sizes produced. This synthesis can also produce nanocrystalline HgTe.
The growth of CuCl/CaF2 heterostructures has been studied with an atomic force microscope (AFM). We have grown by molecular beam epitaxy (MBE) CuCl thin films at various substrate temperatures and thicknesses on CaF2(...
The growth of CuCl/CaF2 heterostructures has been studied with an atomic force microscope (AFM). We have grown by molecular beam epitaxy (MBE) CuCl thin films at various substrate temperatures and thicknesses on CaF2(111) substrates. AFM studies reveal that islanding is the dominant growth mechanism. We calculated the height-height correlation function, 〈lh(qt)¦2〉, for each of our films and compared them to the predictions made by the Shadowing Growth Theory, a preexisting growth model that enabled us to extract the important kinetic parameter of surface diffusion length for the growth condition of each of the four films.
The technique of high-resolution electron microscopy represents a powerful method for characterizing the microstructure of thin films and surfaces. We demonstrate its usefulness by reference to some recent studies of ...
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