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Dry sliding wear of laser-clad high-vanadium Crucible Powder Metallurgy (CPM) 3V, 9V, and 15V tool steel coatings was investigated in “as-clad” and “heat-treated” conditions against cemented WC-6%Co ball, where a hardened wrought AISI H13 hot-work tool steel substrate was used as a baseline for comparison. The 15V coating demonstrated a superior sliding wear resistance; the 9V coating possessed a better sliding wear resistance than the 3V coating, but was inferior to the 15V coating, and all the laser-clad CPM coatings showed a better sliding wear resistance than the hardened H13 substrate. The sliding wear resistances of the 3V and 15V coatings were further improved after double tempering at 540 and 550 °C (corresponding to their respective “secondary hardening”), respectively. By contrast, the sliding wear resistance of the 9V coating after double tempering at 550 °C (beyond its “secondary hardening” temperature) was slightly dropped instead, ascribed to the reduced hardness. The microstructures of the coatings, the morphologies, and chemical compositions of the worn surfaces were studied, revealing that the adhesion and oxidation played important roles in the dry sliding wear, depending upon the hardness of the martensitic matrices of the coatings and the morphologies and amount of (V, Cr)8C7 vanadium carbides dispersed on the matrices.

Incompatibilities of thermo-physical-mechanical as well as metallurgic properties between dissimilar Ti and Ni metals present technical challenges to their fusion joining. In this manuscript, using a high power continuous wave (CW) YAG laser, a direct butt welding of Ti and Ni plates was performed with a relatively large beam offset from the contact interface between two base metals (BMs) toward either side of the BMs. As a result, a large amount of rapidly solidified non-equilibrium solid solution occurred in the main fusion zone (FZ); while the total amount of prior intermetallic compounds (IMCs) such as Ti2Ni, Ni3Ti and NiTi significantly decreased, most of which were primarily located as a band (less than 200 μm wide) along one of the fusion interfaces with the BMs. When the laser beam was shifted 0.5 mm toward the Ni side, the toughness of the FZ was sufficiently improved, leading to a crack-free joint. In this study, the microstructures, chemical compositions, and microhardness in the laser-welds thus obtained were examined to learn the influences of beam offset on laser weldability of Ti to Ni metals.

The nickel interlayer improved the laser weldability of Zr-2.5Nb to AISI 410 stainless steel. The fusion zone contained a large amount of refined and tough dendritic γ-Ni(Fe, Cr) solid solution (182 ∼ 268 HV), while the brittle Zr(Fe, Cr)2 intermetallic compound (1171 ∼ 1460 HV), which was the main phase as the result of direct welding of Zr-2.5Nb to SS410 as well as the source responsible for the welding cracks, disappeared. Only limited quantities of Zr2(Ni, Fe), Zr7Ni10 (and/or Zr2Ni7) intermetallics were present mainly in the form of thin layers (less than 200 μm thick in total) near the fusion interface with Zr-2.5Nb. Those Zr-Ni based intermetallics showed relatively higher toughness and lower hardness (301 ∼ 497 HV) than the brittle Zr(Fe, Cr)2, which reduced the overall cracking sensitivity of the laser-weld.

There are many advantages in the Isolated Bidirectional DC-DC Converter with Dual-Active-Bridge (IBDC-DAB) such as zero voltage switch, good power system reliability and high power density. This circuit topology has been used in the power grid, electric motor, etc. This paper present the numerical and simulation modeling and analysis to the IBDC-DAB. Four working modals of the circuit topology is discussed and the current expression is established. The simulation model is carried out in Saber and the simulated waveform is attained. Finally, IBDC-DAB circuit is fabricated in experiment and the waveforms are verified.

In this article, laser cladding process with a blown powder feeding was used to deposit nickel-based IN-625 superalloy, cobalt-based hardfacing Stellite 6 alloy and high-vanadium CPM 10V tool steel onto a similar or dissimilar base material, respectively, to investigate the development and controllability of process-induced residual stresses in the clad and to analyse their correlation with microstructural evolutions of the clad and heat-affected zone (HAZ) during cladding and post-heat treatments. The residual stresses were evaluated using the hole-drilling method as per ASTM E837-95, whereas the microstructures were studied using X-ray diffractometer, optical microscope and scanning electron microscope. A particular attention was paid to combined effect of both clad and HAZ on the build-up of residual stresses in the clad. It is expected that the experimental results will form a useful addition to the existing knowledge with respect to the topic and, more significantly, to promote confidence on industrial applications of laser-clad IN-625, Stellite 6 and CPM 10V materials.

A new system, (La 0.8 Sr 0.2 ) 1 − x Ag x MnO 3+ δ (LSAM, x ≤ 0.2), is developed as current collector for solid oxide fuel cell (SOFC). LSAM is prepared by a modified sol–gel method and presents a single phase. The shrinkage temperature reduces from 1150 °C to 800 °C with an addition of 15 mol% Ag to La 0.8 Sr 0.2 MnO 3+ δ (LSM20). The contact resistance between the current collector and the cathode is measured, and the influence of Ag content on the contact resistance is investigated. The result shows that the contact resistance using (La 0.8 Sr 0.2 ) 0.85 Ag 0.15 MnO 3+ δ (LSAM15) as current collector is about 12 mΩ cm 2 at 750 °C, which is close to the value using expensive Pt paste as current collector. This new system is a promising current collecting material for the practical application of SOFC.

Laser consolidation (LC) is a laser cladding based material additive process that could fabricate a “net-shape” functional metallic part through a “layer-upon-layer” deposition directly from a CAD model. The LC process can produce nickel-base IN-738 superalloy with metallurgical soundness. Nevertheless, due to process-induced rapid directional solidification, the LC IN-738 alloy demonstrates certain unique microstructural characteristics, such as, the presence of non-uniform coarse columnar grains (a majority of the grains is in the range of about 56–158 μm in diameter; but their lengths could vary from several hundred μm to the height of the wall being built up) in combination with exceptionally fine directionally solidified dendrites inside (the secondary dendritic arm spacing is about 1.7 μm). Moreover, the “as-consolidated” LC IN-738 alloy, in nature, is a supersaturated γ solid solution, and any precipitation of γ′ particles from the γ matrix is effectively suppressed. Post heat treatment, thus, is essential to achieve the required operational microstructure. On the other hand, the nature and role of conventional “solution plus aging” treatment to the LC IN-738 alloy seem to be different as compared to “as-cast” or wrought IN-738 alloy. In this paper, process-induced microstructural characteristics of the LC IN-738 alloy and its development brought by post heat treatment were fully investigated. The implication on high-temperature mechanical performance of the LC alloy was discussed as well.

Objective The aim of the study was to construct recombinant type 5 adenovirus expressing the human DBC2 (deleted in breast cancer 2) gene for in vitro and in vivo assay in human bladder cancer research.

Laser consolidation (LC) is a novel additive manufacturing process being developed by the National Research Council Canada (NRC) at its London facility. LC offers unique capabilities in the production of net-shape functional metallic parts requiring no further post-machining. NRC’s LC technology has achieved dimensional accuracy of up to +/−0.05 mm with a surface finish up to 1 μm Ra (depending on the materials used in the manufacturing process). The LC process differs from other additive manufacturing technologies by its high precision deposition system that can build functional parts or features on top of existing parts using various high performance materials and alloys. In this paper, laser consolidation of various high performance materials (such as Ni-base super alloys and Ti-6Al-4V alloy) will be discussed and the examples will be given on building complex functional components and repairing parts otherwise unrepairable for gas turbine and other applications., ASME Turbo Expo 2015: Turbine Technical Conference and Exposition, June 15–19, 2015, Montreal, QC, Canada

AISI H13 hot-work tool steel has a wide application for mold/die of die casting, hot forging, hot extrusion, hot stamping and plastic injection molding, due to its high toughness, high hot hardness and high thermal fatigue resistance. Laser cladding, a material additive technology, can be used to apply various functional coatings and to repair/reconfigure tool/die. H13 tool steel was successfully laser-clad on carbon steel substrates at room temperature. The microstructure of as-clad coating showed a refined dendritic structure due to fast cooling and rapid solidification. X-ray diffraction (XRD) phase identification revealed that the coating consisted of a majority of martensite phase plus certain amount of retained austenite phase (∼ 20 vol%). Tensile residual stresses were measured in the as-clad H13 coating. The average value of Vickers hardness in the as-clad coating is about 575 Hv0.05. Wear resistance evaluation using pin-on-disc sliding wear testing showed that the wear resistance of as-clad H13 steel coating was similar to or slightly better than that of hardened wrought H13 steel (HRC 54) plate under the wear test condition used in this study, but the wear mechanisms are significantly different., 142nd Annual Meeting and Exhibition: Linking Science and Technology for Global Solutions, March 3-7 2013, San Antonio, TX, USA

As a novel computer-aided materials additive manufacturing process, the freeform laser consolidation (LC) can directly produce functional shapes (features or structures) through a "layer-upon-layer" deposition. In this research, LC processability of both H13 and CPM 9V tool steels and their mechanical performance thus obtained were investigated. Both laser-consolidated tool steels were metallurgically sound with no crack, exhibiting layer-wise refined solidified structures with dominated martensite and small amount of retained austenite, as well as composition-dependent carbides. Laser-consolidated H13 could outperform its wrought counterpart mechanically as measured by tensile strength/strain, and bonding strength as well as sliding wear resistance; laser-consolidated CPM 9V could provide excellent sliding wear resistance superior to the conventional widely used tool steel (such as wrought D2). These unique microstructures and mechanical properties could be tailored for niche applications in additive manufacturing of tools, molds, and dies. © 2013 Her Majesty the Queen in Right of Canada.

National Research Council Canada (NRC) has developed precision laser additive repair of worn gas turbine components. The repair system uses integrated 3D mapping and laser additive deposition. The integrated inspection and repair system is capable of inspecting and repairing a worn gas turbine injector in less than one hour. This innovative system dramatically improves repair time and cost of high value gas turbine components. In this paper, a case study will be presented as a joint effort by NRC and UTC Aerospace Systems to evaluate the feasibility of repair of worn fuel injectors from a land based gas turbine engine. The project evaluated the use of laser cladding of cobolt alloy L-605 for repair of worn engine components on a Rolls Royce 501K engine. Test results reveals that laser clad L-605 on wrought L-605 substrate demonstrates comparable or even substantially improved fatigue life as compared to the baseline L-605 specimens at elevated temperature. Laser clad L-605 also shows comparable wear resistance. The paper will demonstrate the improved repair of the fuel injectors via laser cladding repair and the metallurgical evaluation of the repair. The paper documents the improvement of the repair from several weeks and fabrication of several placement componenets to a matter of only a few hours to inspect and repair using the NRC laser additive manufacturing system., On CD-ROM, 32nd International Congress on Applications of Lasers and Electro-Optics (ICALEO), 2013, Miami FL, USA

Laser consolidation (LC) developed by National Research Council's Industrial Materials Institute (NRC-IMI-London) since mid-1990s, is a laser cladding based rapid manufacturing and material additive process that could fabricate a "net-shape" functional metallic shape through a "layer-upon-layer" deposition directly from a computer aided design model without using molds or dies. In order to evaluate the LC processability of different materials, some representative nickel-based superalloys (IN-625, IN-718, IN-738, and Waspaloy), stainless steels (austenitic SS316L and martensitic SS420), and lightweight alloys (Ti-6Al-4V titanium alloy and Al-4047 aluminum alloy) have been investigated. Like other laser cladding based processes, due to process-induced rapid directional solidification, the LC alloys have demonstrated certain unique morphological characteristics. Moreover, the "as-consolidated" LC alloys, in nature, are in the "as-quenched" state, and some precipitation processes from their matrices, which are sometimes critical to the development of mechanical performance of the materials, could be effectively suppressed or retarded. Post-heat treatments, therefore, could necessarily facilitate the process of achieving their required operational microstructures. In this article, a comprehensive investigation was performed including metallurgical soundness and process-induced morphological characteristics of the LC materials, and microstructure development brought by post-LC heat treatments using optical microscope, scanning electron microscope, and X-ray diffraction. The implications on the mechanical performance of the LC materials were discussed as well in order to provide essential information for potential industrial applications of the LC materials. © 2011 Her Majesty the Queen.

Pratt and Whitney Canada specializes on the design and manufacturing of aerospace gas turbine engines, which requires advanced technologies to extend components life to reduce maintenance cost. Laser cladding provides unique capabilities for repairing damaged components that currently are difficult or even impossible to be repaired using conventional methods. In this paper, laser cladding of IN-625 alloy was investigated. Testing results reveals that laser clad IN-625 on wrought IN-625 substrate demonstrates comparable or even substantially improved fatigue life as compared to the baseline IN-625 specimens at the room temperature as well as at elevated temperature. Laser clad IN-625 also shows slightly improved wear resistance. Therefore, laser cladding of IN-625 is very attractive for repairing various damaged wrought IN-625 components for aerospace gas turbine engines. A case study will also be presented on laser cladding of IN-625 to repair damaged fuel nozzles that currently can not be repaired using conventional method., 28th International Congress on Applications of Lasers and Electro Optics, November 2-5 2009, Orlando, FL, USA

Laser consolidation (LC) is a laser cladding based novel manufacturing process that produces net-shape functional components directly from a CAD model. As an alternative to conventional machining processes, the LC process builds complete net-shape functional parts or features on existing parts by adding instead of removing material. In this paper, laser consolidation of Waspalloy and IN-718 alloys is demonstrated. The LC process successfully built metallurgically sound Waspalloy and IN-718 alloy samples. The microstructures of as-consolidated and heat-treated Waspalloy and IN-718 materials were examined. Their tensile properties were evaluated and compared with reference data. In addition, several LC Waspalloy and IN-718 samples that are difficult or impossible to make using conventional manufacturing technologies were produced to demonstrate the capability of the process., ICALEO 2008, 27th International Congress on Applications of Lasers and Electro-Optics, Congress Proceedings, October 20th to 23rd, 2008, Temecula, CA, USA

A comparative study of the abrasive wear behaviour has been conducted on several tool steel coatings that were deposited by laser cladding process using a CW CO 2 laser in combination with a blown powder feed technique. The laser-clad CPM 15V and CPM 10V coatings exhibit superior abrasive wear resistance as compared with the reference material, AISI D2 tool steel. In contrast, the wear resistance of the CPM 9V and M4 coatings is inferior to that of the D2 steel. As multiple overlapping clad-tracks are used to produce a coating covering relatively large area, a thin layer of a pre-deposited clad-track will be “over-heated” while depositing the next adjacent one. Depending on the coating material, this re-heated zone (RHZ) can exhibit different wear rate compared with the other area of the track in the as-clad condition, which is especially significant for the CPM 10V coating. For coatings with a large proportion of retained austenite, post heat-treatment promotes the transformation of the retained austenite to martensite, improving the wear resistance. The wear resistance of tool steel coatings is dependent upon the matrix microstructure and the features of dispersed carbides, such as their type, proportion, shape, size and distribution.

Laser consolidation (LC) is a novel manufacturing process that produces net-shape functional and metallurgically sound components by adding material based on a CAD model. In this paper, laser consolidation of Al 4047 alloy is demonstrated. The LC process successfully built metallurgically sound Al 4047 alloy samples on a Al 6061 substrate. The microstructure of LC Al 4047 material was examined in detail using optical microscope, scanning electron microscope (SEM) and x-ray diffraction (XRD) techniques, while its chemical composition was analysed by x-ray energy dispersive spectroscopy (EDS). The tensile properties of the LC Al 4047 material were evaluated and compared with similar wrought and cast aluminum alloys. In addition, several LC Al 4047 samples were produced to demonstrate the capability of the process. Laser consolidation of Al alloys has many potential applications in aerospace, mold-making and other industries for rapid tooling, small quantity production, and repair of expensive components., ICALEO 2005, October 31st to November 3rd 2005, Miami Florida

Laser consolidation is an emerging novel computer-aided manufacturing process that produces net-shape functional parts layer by layer directly from a CAD model by using a laser beam to melt the injected powder and re-solidifying it on the previous pass. As an alternative to the conventional machining process, this novel manufacturing process builds complete net-shape functional parts or features on an existing part by adding instead of removing material. Ti-6Al-4V alloy is widely used in the aerospace, medical and other industries. In this work, functional properties of laser consolidated Ti-6Al-4V have been investigated. The laser consolidated Ti-6Al-4V material is metallurgically sound and free of cracks and porosity. The components built by the laser consolidated Ti-6Al-4V show good surface finish and dimensional accuracy. The mechanical properties of laser-consolidated Ti-6Al-4V samples are evaluated. The microstructure is analyzed in details using optical microscope, scanning electron microscope (SEM) and x-ray diffraction (XRD). Composition of the laser-consolidated Ti-6Al-4V material is also analyzed by energy dispersive spectroscopy (EDS).Laser consolidation is an emerging novel computer-aided manufacturing process that produces net-shape functional parts layer by layer directly from a CAD model by using a laser beam to melt the injected powder and re-solidifying it on the previous pass. As an alternative to the conventional machining process, this novel manufacturing process builds complete net-shape functional parts or features on an existing part by adding instead of removing material. Ti-6Al-4V alloy is widely used in the aerospace, medical and other industries. In this work, functional properties of laser consolidated Ti-6Al-4V have been investigated. The laser consolidated Ti-6Al-4V material is metallurgically sound and free of cracks and porosity. The components built by the laser consolidated Ti-6Al-4V show good surface finish and dimensional accuracy. The mechanical properties of laser-consolidated Ti-6Al-4V samples are evaluated. The microstructure is analyzed in details using optical microscope, scanning electron microscope (SEM...