SFF Papers from UCONN Sponsored by ONR/ARPA

Note: The following 5 articles appear in the Proceedings of the 1995 Solid Freeform Fabrication Symposium at the University of Texas at Austin

Selective Laser Sintering Preparation And Tribological Testing Of Nanostructured Tungsten Carbide-Cobalt Composites by Rand D. Cottle, Britton Birmingham, and Zwy Eliezer Center for Materials Science and Engineering and The Department of Mechanical Engineering The University of Texas at Austin Austin, TX 78712 and Harris L. Marcus Institute of Materials Science The University of Connecticut 97 North Eagleville Road Storrs, Connecticut 06269-3136 ABSTRACT This paper describes the results to date of research done to compare and contrast the tribological properties of nanostructured tungsten carbide-cobalt composites consolidated by selective laser sintering (SLS) and conventional grain size composites of the same chemical composition consolidated by conventional commercial methods. The powder preprocessing and selective laser sintering methods will briefly be described. The tribological testing methods will be discussed, and the tribological properties of the selective laser sintered and commercially consolidated materials will be compared. It will be seen that the nanosized WC-CO composites have far superior harness and wear resistance compared to their microsized counterparts. Densification Behavior Of Sls Processed Al₂O₃/Al Composite by T. Srinivasa Rao Regional Engineering College Trichy-620 015, India and D.L. Bourell Center for Materials Science and Engineering The University of Texas at Austin Austin, TX 78712 and Harris L. Marcus Institute of Materials Science The University of Connecticut 97 North Eagleville Road Storrs, Connecticut 06269-3136 ABSTRACT Production of structurally sound parts by any rapid prototype technique is essential, because fully function features are necessary where application testing is required. In the present work, a powder blend of Al₂O₃/Al (3:1 by weight) was mixed with ammonium dihydrogen phosphate and subjected to selective laser sintering (SLS) using a CO₂ laser. An attempt has been made to increase the powder bed density by introducing vibration to the part cylinder. These SLS processed preforms were than subjected to a secondary heat treatment in a hydrogen atmosphere and to hot isostatic pressing. Densification behavior of these Al₂O₃/Al composite preforms is discussed. Fundamentals Of Liquid Phase Sintering During Selective Laser Sintering by D.E. Bunnell, S. Das, D.L. Bourell, and J.B. Beaman Center for Materials Science and Engineering The University of Texas at Austin Austin, TX 78712 and Harris L. Marcus Institute of Materials Science The University of Connecticut 97 North Eagleville Road Storrs, Connecticut 06269-3136 Introduction

One of the advantages of the Selective Laser Sintering (SLS) process is that a variety of materials can br processed. However, the goal of being able to produce fully dense metal parts with no post processing has been elusive. Using Selective Laser Sintering to produce metal parts with full density without post processing poses a challenge since both the processing conditions and the metal system must be controlled. This article describes two metallurgical mechanisms by which loose metal powder beds could be sintered to nearly full density using a scanning laser beam. The mechanisms are particle rearrangement during liquid phase sintering (LPS) and in-situ infiltration. Some of the particles, when heated by the laser radiation, melt and form a liquid. If this liquid has certain physical properties (e.g., low viscosity and high surface tension) and wets the other solid particles, then the SLS process can in theory produce dense layers by either mechanism. The purpose of this study is to determine the process and material selection parameters required to achieve fully dense parts during direct Selective Laser Sintering of metal.

Selective Laser Sintering Of Alumina-Zinc Borosilicate Glass Composites Using Monoclinic Hbo₂ As A Binder by Insup Lee, and A. Manthiram Center for Materials Science and Engineering, ETC 9.104 The University of Texas at Austin Austin, TX 78712 and Harris L. Marcus Institute of Materials Science The University of Connecticut, U-136 97 North Eagleville Road Storrs, Connecticut 06269-3136 ABSTRACT

Selective Laser Sintering (SLS) process has been employed to fabricate alumina-glass composites using as an inorganic binder monoclinic HBO₂. Subsequent post-thermal processing of green SLS parts at various temperatures yielded glass-ceramic composites. The crystalline phases and microstructural evolution at each firing temperature were identified by X-ray diffraction analysis and Scanning Electron Microscopy. The role of glass content, firing temperature, and alumina particle size on the densification and bend strength of fired samples were studied. In addition, further densification was made through infiltration of colloidal silica into the fired, porous samples.

Solid Freeform Fabrication Of Silicon Nitride Shapes By Selective Laser Reaction Sintering (SLRS) by B.R. Birmingham Center for Materials Science and Engineering The University of Texas at Austin Austin, TX 78712 and Harris L. Marcus Institute of Materials Science The University of Connecticut 97 North Eagleville Road Storrs, Connecticut 06269-3136 ABSTRACT Selective Laser Reaction Sintering is a variation of selective laser sintering that incorporates an in-situ reaction under the scanned beam to fabricate shapes from materials not directly accessible by traditional SLS. This paper describes an investigation into the production of silicon nitride (Si₃N₄) shapes by laser sintering silicon powder in an ammonia (NH₃) atmosphere. The effect of gas pressure and the importance of gas/laser interactions are discussed. Single and multiple layer shapes are fabricated. The material is analyzed by X-ray diffraction spectroscopy (XRDS) for phase content and scanning electron microscopy (SEM) for macrostructure. Data is presented that demonstrates conversion rates from silicon to silicon nitride on the order of 85%.

The following article appeared in the French review "Vigie Prototypage Rapide", published by the Agence pour la Diffusion de l'Information Technologique.

Gas Phase Solid Freeform Fabrication Techniques Harris L. Marcus, Shay Harrison, and James E. Crocker Institute of Materials Science University of Connecticut Storrs, CT 06269-3136 Introduction

Gas phase solid freeform fabrication (SFF) is a distinct subset of SFF that uses gas phase precursors as the sources for the deposited material. Selective Laser Reaction Sintering (SLRS), Selective Area Laser Deposition (SALD), and Selective Area Laser Deposition Vapor Infiltration (SALDVI) are all gas phase SFF procedures, which are carried out in an environmental chamber to ensure the quality and content of the materials in the deposits. Each has unique features that lead to three dimensional fabricated shapes in a wide variety of materials.

The following article appeared in the special anniversary edition of The Journal of Engineering for Industry

Rapid Prototyping and Solid Freeform Fabrication by James G. Conley McCormick School of Engineering and Applied Science Northwestern University Evanston, Illinois 60208-3111 and Harris L. Marcus Institute of Materials Science The University of Connecticut, U-136 97 North Eagleville Road Storrs, Connecticut 06269-3136 ABSTRACT This article will address a brief review of the state-of-the-art in commercial practice and advanced research in the field of Rapid Prototyping with special attention to the additive methods of Solid Free Form Fabrication. Recent applications of this technology in computer integrated manufacturing environments will be outlined. Future applications and research in new materials will also be addressed.

The following papers are found in the 1996 Solid Freeform Fabrication Symposium Proceedings

Solid Freeform Fabrication at The University of Connecticut by Shay Harrison, James E. Crocker, Tariq Manzure, and Harris L. Marcus Institute of Materials Science University of Connecticut Storrs, CT 06269-3136 ABSTRACT Gas phase solid freeform fabrication research at The University of Connecticut focuses on two main procedures, Selective Area Laser Deposition (SALD) and Selective Area Laser Deposition Vapor Infiltration (SALDVI). A SFF research laboratory is under construction at UCONN, with two new operation systems. These systems possess temperature control, data acquisition capabilities, in-situ video monitoring, and the ability to fabricate SALDVI parts up to four inches wide by four inches long. The procurement of a harmonic generating Nd:YAG six watt laser, capable of producing output at 532, 355, and 266 nanometer wavelengths, as well as a coupled effort with the Photonics Center at the University providing laser diodes at a variety of wavelengths, presents the opportunity to explore interactions involved in gas reactions driven by lasers. Investigations of material systems will include ceramic carbides, nitrides, and their composites, as well as metals. SFF Using Diode Lasers Tariq Manzur, Chandra Roychoudhuri, and Harris L. Marcus Photonics Research Center and the Insitute of Materials Science Institute of Materials Science University of Connecticut Storrs, CT 06269-3136 ABSTRACT Rapid prototypings using direct selective laser sintering(SLS) of metal/ceramic powders have a great potential for design and fabrication of near net shape of metal/ceramic parts. At present, CO2,Nd:YAG and excimer lasers are the only possible solutions for heavy duty manufacturing applications. At the University of Connecticut, researchers advanced the concept of rapid prototyping and other desktop manufacturing tasks such as welding, sintering, drilling, marking, soldering of electronic components, face hardening of metal and other materials applications by use of high power diode lasers.

Utilizing SLS techniques and approaches designed to harness the full potential of diode lasers, a computer controlled sintering sytem was developed. The system is capable of producing complex three dimensional shapes of metal ceramic parts from CAD/CAM solid model data files. In the paper, direct sintered iron-bronze parts using high power laser diodes has been demonstrated. The system comprises of high power laser diodes(25 watts CW, wavelength of 980 nanometers, and a 60 watt pulse or cw, wavelength of 810 nanometers), beam scanning systems, atmospheric controlled chamber, and CAD/CAM software.

The following paper was published in the IMECE Symposium on Rapid Response Manufacturing, ASME Manufacturing Division, held in November, 1996

Solid Freeform Fabrication: An Overview Harris Marcus, Shay Harrison, and James E. Crocker Institute of Materials Science University of Connecticut Storrs, CT 06269-3136 ABSTRACT Solid freeform fabrication (SFF) has become a prominent area of interest and research in the last 10 years. SFF produces parts directly through additive procedures, without any part-specific tooling. The design for the part originates in a Computer Aided Modelling (CAD) file which is a three dimensional representation of the part that is sectioned into thin two dimensional layers from which the part is built. SFF vastly enhanced the prototype production process, and now looks to make advacnes for short run productions and tool and dies. This paper presents an overview of SFF, in terms of where it has been, what it is today, and where it will go in the future.

The following paper was published in the 7th International Conference on Rapid Prototyping Proceedings, in April, 1997,

Recent Advances In SALD And SALDVI by B.R. Birmingham, M.S. Shaarawi, J.V. Tompkins, and J. Sanchez Center for Materials Science and Engineering The University of Texas at Austin Austin, TX 78712 and K.J. Jakubenas, S. Harrison, J.E. Crocker, and Harris L. Marcus Institute of Materials Science The University of Connecticut 97 North Eagleville Road Storrs, Connecticut 06269-3136 ABSTRACT This paper describes the recent advances in SALD/SALDVI that have occurred in the cooperative University of Texas/University of Connecticut projects. The paper includes a discussion of efforts to model the SALD and SALDVI processes, including both thermodynamic and kinetic based approaches. Also included is a discussion of equipment changes and additions that have been made in order to address processing difficulties discovered by past experimentation and to facilitate future investigations of new variations of the processes. Finally, applications that are currently being researched will be discussed.

The following article appeared in the 1997 TMS Materials Week Proceedings, Symposium on Joining and Repair of Gas Turbine Components

Joining of Silicon Carbide by Selective Area Laser Deposition(SALD) by K.J. Jakubenas, S. Harrison, J.E. Crocker, and H.L. Marcus Institute of Materials Science University of Connecticut, U-Box 136 Storrs, CT 06269-3136 And B.R. Birmingham, J.V. Tompkins, and J.M. Sanchez Center for Materials Science and Engineering The University of Texas at Austin Mail Code C2201 Austin, TX 78712 ABSTRACT

Selective Area Laser Deposition (SALD) is a gas phase technique being evaluated for joining ceramic materials, especially silicon carbide. In joining by SALD, a laser is used to selectively heat the joint and decompose a reactant gas to produce a filler material. Joining by SALD has the potential to form monolithic ceramic joints because the use of braze materials is avoided.
This paper provides a process overview, description of equipment, and the results of experiments in joining by SALD to create monolithic silicon carbide joints.
This work is supported by ONR under Grant # N00014-95-1-0978 and by United Technologies - Pratt & Whitney.

The following paper appears in the 6th European Conference on Rapid Prototyping and Manufacturing, Nottingham, England, in July, 1997 and also will be published in the Rapid Prototyping Journal

Selective Area Laser Deposition(SALD) of Titanium Oxide by K.J. Jakubenas and H.L. Marcus Institute of Materials Science University of Connecticut, U-Box 136 Storrs, CT 06269-3136 And M.S. Shaarawi and J.M. Sanchez Center for Materials Science and Engineering The University of Texas at Austin Mail Code C2201 Austin, TX 78712 And Y.L. Lee Samsung Motors Inc. Testing and Development Team 493 Banwol-Ri, Taean-Eup, Hwasung-Kun Kyungki-Do, Korea 445-970 ABSTRACT

A methodology for study of Selective Area Laser Deposition (SALD), a gas based solid freeform fabrication technique, has been developed that proceeds through three steps: selection of a precursor, thermodynamic calculations for deposition conditions, and experimentation. Proof of the usefulness of these three steps in depositing high quality (transparent) titanium oxide is presented. This paper stresses the connections between the steps and shows how this approach can be applied to SALD of other materials, including complex ceramics, intermetallics, and / or composite systems.

The following 4 papers appear in the 1997 Solid Freeform Fabrication Symposium Proceedings

The Use of VRML to Integrate Design and Solid Freeform Fabrication by Yanshuo Wang and Harris L. Marcus Institute of Materials Science Solid Freeform Fabrication Laboratory University of Connecticut, U-Box 136 Storrs, CT 06269-3136 And Jian Dong Boeing North American Inc. Space Systems Division Downey, CA 90242 ABSTRACT

The Virtual Reality Modeling Language (VRML) was created to put interconnected 3D worlds onto every desktop. The 3D VRML format has the potential for 3D fax and Tele-Manufacture. An architecture and methodology of using VRML format to integrate a 3D model and Solid Freeform Fabrication system are described in this paper. The prototype software discussed in this paper demonstrates the use of VRML for Solid Freeform Fabrication process planning. The path used from design to part will be described.

Fabrication of In-situ SiC/C Thermocouples by Selective Area Laser Deposition by Lianchao Sun, Kevin J. Jakubenas, James E. Crocker, Leon L. Shaw, and Harris L. Marcus Institute of Materials Science University of Connecticut, U-Box 136 Storrs, CT 06269-3136 ABSTRACT

With the intrinsic nature to process relatively small features, selective area laser deposition (SALD) is a potential technique to fabricate complex shaped macro-components with in-situ high-resolution micro-devices. In this study, SALD was used to deposit in-situ silicon carbide/carbon (SiC/C) thermocouples on alumina and silicon carbide substrates with a CO2 laser. Tetramethylsilane (TMS) and acetylene (C2H2) were chosen as precursors for deposition of the silicon carbide and carbon lines respectively. The electromotive force (emf) of the deposited thermocouple was measured and found to respond sensitively to temperature variations from room temperature to 8000C. The effect of the deposition parameters on the product morphology was also investigated.

Gas Phase SFF Control System for Silicon Nitride Deposition by SALD/SALDVI by Shay Harrison, Kevin J. Jakubenas, James E. Crocker, Chris E. Costa, and Harris L. Marcus Institute of Materials Science Solid Freeform Fabrication Laboratory University of Connecticut, U-Box 136 Storrs, CT 06269-3136 ABSTRACT

A closed-loop laser scanning and temperature control system has been developed for SALD/SALDVI. Temperature control is especially important in SALD/SALDVI because temperature plays a defining role in both composition and deposition rate. The control system for SALD/SALDVI is presented which provides .STL file interpretation, real time temperature control, and laser response modeling, all on a PC. This control system was utilized with the SALD/SALDVI techniques for depositing silicon nitride. Characteristics of Si3N4 fabricated shapes are discussed, including composition, morphology, and electrical properties.

SALDVI Optimization for the Tetramethylsilane-Silicon Carbide System by James E. Crocker, Kevin J. Jakubenas, Shay Harrison, and Harris L. Marcus Institute of Materials Science Solid Freeform Fabrication Laboratory University of Connecticut, U-Box 136 Storrs, CT 06269-3136 ABSTRACT

Selective Area Laser Deposition Vapor Infiltration (SALDVI) of silicon carbide powder infiltrated with silicon carbide deposited from tetramethylsilane (TMS) has been studied. The effects of deposition time and temperature and starting substrate powder are discussed. The discussion centers on the efforts to properly balance theses parameters to produce multi-layered shapes with structural integrity, particularly for use as the matrix material for shapes containing embedded devices. This includes optimizing scan speed, deposition temperature, and initial powder properties to maximize infiltration to increase density and layer to layer bonding, and minimize excessive deposition to maintain critical dimensions. Initial powder properties are also optimized to minimize bulk motion in the powder bed during deposition which was observed and identified as a mechanism that reduces inter-layer bonding. We acknowledge the support of ONR/ARPA.

The following paper has been accepted for publication in the December, 1998 issue of JOM

Gas (SALD) and Gas/Powder (SALDVI) Solid Freeform Fabrication (SFF) James E. Crocker, Shay Harrison, Lianchao Sun, Leon L. Shaw, and Harris L. Marcus Institute of Materials Science University of Connecticut, Storrs ABSTRACT Two techniques for Solid Freeform Fabrication using gas precursors and localized laser heating are Selective Area Laser Deposition (SALD) and Selective Area Laser Deposition Vapor Infiltration (SALDVI). The concepts, capabilities, and processing issues of the two techniques are described. An example of a multiple material structure fabricated using SALD and SALDVI illustrates the versatility of these developing processes.

The following paper has been accepted for publication in the Naval Research Reviews

Gas Phase Solid Free-Form Fabrication and Joining of Ceramics by K.J. Jakubenas, J.E. Crocker, S. Harrison, L. Sun, L. Shaw, H.L. Marcus Institute of Materials Science, University of Connecticut Abstract Structural ceramic materials are finding growing use in a wide range of applications, particularly advanced power generation and propulsion systems. Yet, applications of ceramics are being limited by the very properties that make them desirable, high temperature stability and high hardness. Conventional forming techniques are severely tested by materials that do not melt, are harder than tool bits, and are not ductile. Even techniques specifically devised for forming ceramics, such as hot isostatic pressing, have strong limitations. Gas phase Solid Free-form Fabrication (SFF) technologies offer the potential to form complex shapes from ceramics and other materials without the restrictions of conventional forming techniques.
Two similar yet distinct gas phase SFF techniques are being investigated as well as a related spinoff technology that complements both SFF and conventional forming techniques. The techniques are Selective Area Laser Deposition (SALD), SALD-Vapor Infiltration (SALDVI), and SALD Joining. The common thread linking the techniques is the use of a laser to create a localized reaction zone which decomposes a reactant gas to deposit material in a spatially controlled manner.
Development and control of gas phase SFF techniques, including shape, composition, and material properties, requires an understanding of the governing physical processes. This paper begins with a description of the underlying physical processes of thermodynamics, kinetics, and heat / mass transport and then shows the experimental effects of these processes. The goals and continuing development of gas phase SFF technology are discussed in light of the governing physical process and experimental results.

The following 3 part paper has been accepted for publication in Materials and Manufacturing Processes, issue #1, vol. 14, 1998

In-Situ Thermocouples in Macro-Components Fabricated Using SALD and SALDVI Techniques: Part I. Thermochemical Modeling Lianchao Sun, Kevin J. Jakubenas, James E. Crocker, Shay Harrison, Leon L. Shaw and Harris L. Marcus Institute of Materials Science University of Connecticut, Storrs, CT 06269-3136 Abstract To fabricate macro-structural SiC components containing an in-situ SiC/C thermocouple using an integrated SALD and SALDVI technique, thermodynamic analyses on the involved reactant gases have been performed with the CET89 code based on the minimization of the system free energy. The gaseous precursors considered include tetramethylsilane (TMS) and methyltrichlorosilane (MTS) for the deposition of silicon carbide, and methane, ethylene and acetylene for the deposition of carbon. Reactions between disilane and acetylene and between TMS and ammonia have also been thermodynamically calculated for the deposition of silicon carbide and silicon nitride (for use as an insulation layer between the thermocouple and the matrix), respectively. Based on these analyses, four characteristic temperature zones have been defined for the decomposition of silicon carbide from TMS. A silicon nitride deposition map has been built for the TMS and ammonia system. The deposition temperature range of silicon nitride is found to increase with the total pressure of TMS plus ammonia and the addition of hydrogen, and be affected by the ratio of TMS to ammonia. The addition of hydrogen also introduces a stable silicon carbide and silicon nitride mixture zone that otherwise does not exist. The co-deposition of graphite with silicon carbide and silicon nitride is found in the TMS-containing systems at certain conditions. However, the threshold temperature at which graphite co-deposition occurs can be increased by the addition of hydrogen, thereby eliminating or reducing the graphite co-deposition. Based on these thermodynamic analyses, the gaseous precursors for the deposition of silicon carbide, silicon nitride and carbon have been selected for further experimental evaluation, the result of which is reported in part II of this series. In-Situ Thermocouples in Macro-Components Fabricated Using SALD and SALDVI Techniques: Part II. Evaluation of Processing Parameters Lianchao Sun, Kevin J. Jakubenas, James E. Crocker, Shay Harrison, Leon L. Shaw and Harris L. Marcus Institute of Materials Science University of Connecticut, Storrs, CT 06269-3136 Abstract

In order to fabricate well-controlled in-situ SiC/C thermocouples embedded within macro-structural SiC components using an integrated Selective Area Laser Deposition (SALD) and the Selective Area Laser Deposition & Vapor Infiltration (SALDVI) technique, the major processing parameters affecting the crystal structure, the deposition rate, surface morphology of deposits, and shapes and sizes of the cross section of deposited lines are evaluated. It is found that the growth rate of SiC deposits increases with temperature and TMS gas pressure over the temperature and pressure range studied. The apparent activation energy for depositing SiC from TMS is 61 kJ/mole in the temperature range from 700 to 12000C and independent of the TMS gas pressure ranging from 20 to 60 torr. The shape and size of the cross section of SiC lines depend strongly on the deposition temperature. XRD examination indicates that the deposition product using a C2H2 precursor at 900oC is crystalline graphite. The crytallinity of Si3N4 deposits is affected by the substrate material even though the deposition temperature and other process parameters are the same. These phenomena have been explained in terms of the growth-controlling mechanisms of deposits, the temperature distribution induced by an incident laser beam, and the thermal conductivity of the substrate.

In-Situ Thermocouples in Macro-Components Fabricated Using SALD and SALDVI Techniques: Part III. Fabrication and Properties of the SiC/C Thermocouple Device Lianchao Sun, Kevin J. Jakubenas, James E. Crocker, Shay Harrison, Leon L. Shaw and Harris L. Marcus Institute of Materials Science University of Connecticut, Storrs, CT 06269-3136 Abstract Fabrication of a SiC/C thermocouple embedded in an arbitrarily-shaped SiC macro-component has been demonstrated using an integrated Selective Area Laser Deposition (SALD) with the closely related Selective Area Laser Deposition Vapor Infiltration (SALDVI) process. SALD is used to make the embedded thermocouple devices in-situ and SALDVI to fabricate the macro-components. The thermocouple elements, silicon carbide and carbon lines, and the electrical insulation layer, Si3N4, have been deposited from tetramethylsilane (TMS), acetylene, and a gas mixture of TMS and ammonia, respectively. It is found that the fabricated in-situ thermocouples respond sensitively to temperature variation. Furthermore, the electric signal of the embedded thermocouple is very stable and reproducible in response to thermal cycling. This is not the case when the thermocouple is not embedded in the SiC matrix because of the oxidation of the thermocouple elements.

The following two papers will appear in the Proceedings of the 1998 Solid Freeform Fabrication Symposium

Preparation and Properties of In-Situ Devices Using the SALD and SALDVI Techniques James E. Crocker, Lianchao Sun, Leon L. Shaw, and Harris L. Marcus Institute of Materials Science University of Connecticut Storrs, CT Abstract

One of the many advantages of Selective Area Laser Deposition (SALD) and Selective Area Laser Deposition Vapor Infiltration (SALDVI) is that they can be used to embed in-situ micro-sensors within macro-components. A single-point SiC/C thermocouple sensor embedded within a SiC macro-component and electrically insulated with silicon nitride layers has been demonstrated1. In many applications, multi-point sensors within a single component are needed, e.g., in monitoring the temperature gradient and distribution at different positions. In this paper, multi-point thermocouple devices are demonstrated. The macro-component is a SiC bulk shape made by infiltrating vapor deposited silicon carbide into a silicon carbide powder bed using the SALDVI technique. Multiple SiC/C thermocouples are embedded in-situ in the SiC bulk shape using the SALD technique. The transient and steady state responses of the embedded thermocouples are compared to reference thermocouples probing the surfaces of the bulk shape.

Gas-Phase Selective Area Laser Deposition(SALD) Joining of SiC Tubes with SiC Filler Material by S. Harrison and H.L. Marcus University of Connecticut Institute of Materials Science 97 North Eagleville Road, U-Box 136 Storrs, CT 06269-3136 (860) 486-4410 Abstract The laser-driven, gas-phase based SFF technique for joining together ceramic components with ceramic filler material, known as Selective Area Laser Deposition(SALD) Joining, was utilized in fabricating joined silicon carbide structures. Specifically, silicon carbide tubes were ‘welded’ together by depositing silicon carbide from a gas phase reaction. Two different precursor environments were examined, one a tetramethylsilane/hydrogen mixture and the other composed of methyltrichlorosilane. The quality of the joints were examined by bend tests and hermeticity measurements. In addition, the composition and morphology of the silicon carbide deposit was studied and is discussed here.