SEARCH · Engineering Papers

Results for “surface finish”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23

All sources NASA NTRS DOE OSTI

DOE OSTI2022

Electron beam surface remelting enhanced corrosion resistance of additively manufactured Ti-6Al-4V as a potential in-situ re-finishing technique

This study explores the effect of surface re-finishing on the corrosion behavior of electron beam manufactured (EBM) Ti-G5 (Ti-6Al-4V), including the novel application of an electron beam surface remelting (EBSR) technique. Specifically, the relationship between material surface roughness and corrosion resistance was examined. Surface roughness was tested in the as-printed (AP), mechanically polished (MP), and EBSR states and compared to wrought (WR) counterparts. Electrochemical measurements were performed in chloride-containing media. It was observed that surface roughness, rather than differences in the underlying microstructure, played a more significant role in the general corrosion resistance in the environment explored here. While both MP and EBSR methods reduced surface roughness and enhanced corrosion resistance, mechanical polishing has many known limitations. The EBSR process explored herein demonstrated positive preliminary results. The surface roughness (R a ) of the EBM-AP material was considerably reduced by 82%. Additionally, the measured corrosion current density in 0.6 M NaCl for the EBSR sample is 0.05 µA cm –2 , five times less than the value obtained for the EBM-AP specimen (0.26 µA cm –2 ).

42 ENGINEERING↗

NASA NTRS1994

Poly(arylene ether imidazole) surfacing films for flat and parabolic structures

Films of thermoplastic poly(arylene ether imidazole)s (PAEIs) are used as surface modifiers for neat resin panels and composite resin panels. The PAEI polymer contains imidazole groups along the backbone which co-cure, i.e., react chemically, with epoxies or bismaleimides during processing and thereby provide excellent adhesion between the PAEI film and an epoxy or bismaleimide neat resin or composite resin facesheet. The film provides good adhesion and a smooth surface to the finished part and acts as a release agent from the mold. The as-processed integral structures have very smooth (specular) surfaces, and since the film releases readily from a glass mold, no release agent is necessary. The PAEI film is thermally stable, resistant to electron radiation, and adheres tenaciously to the facesheet. The film maintains good adhesion even after thermal cycling from room temperature to approximately -196 C.

Connell, John W.↗

NASA NTRS1996

Poly(arylene ether imidazole) surfacing films for flat and parabolic structures

Films of thermoplastic poly(arylene ether imidazole)s (PAEI)s are used as surface modifiers for neat resin panels and composite resin panels. The PAEI polymer contains imidazole groups along the backbone which co-cure, i.e., react chemically, with epoxies or bismaleimides during processing and thereby provide excellent adhesion between the PAEI film and an epoxy or bismaleimide neat resin or composite resin facesheet. The film provides good adhesion and a smooth surface to the finished part and acts as a release agent from the mold. The as-processed integral structures have very smooth (specular) surfaces, and since the film releases readily from a glass mold, no release agent is necessary. The PAEI film is thermally stable, resistant to electron radiation, and adheres tenaciously to the facesheet. The film maintains good adhesion even after thermal cycling from room temperature to .about. -196.degree. C.

Connell, John W.↗

NASA NTRS1934

Effect of the Surface Condition of a Wing on the Aerodynamic Characteristics of an Airplane

In order to determine the effect of the surface conditions of a wing on the aerodynamic characteristics of an airplane, tests were conducted in the N.A.C.A. full-scale wind tunnel on the Fairchild F-22 airplane first with normal commercial finish of wing surface and later with the same wing polished. Comparison of the characteristics of the airplane with the two surface conditions shows that the polish caused a negligible change in the lift curve, but reduced the minimum drag coefficient by 0.001. This reduction in drag if applied to an airplane with a given speed of 200 miles per hour and a minimum drag coefficient of 0.025 would increase the speed only 2.9 miles per hour, but if the speed remained the same, the power would be reduced 4 percent.

AIRPLANES - FAIRCHILD 22 (Amer ) WIND TUNNEL TEST↗

NASA NTRS2002

Properties of M40J Carbon/PMR-II-50 Composites Fabricated with Desized and Surface Treated Fibers. Characterization of M40J Desized and Finished Fibers

To increase performance and durability of high temperature composites for potential rocket engine components, it is necessary to optimize wetting and interfacial bonding between high modulus carbon fibers and high temperature polyimide resins. It has been previously demonstrated that the electro-oxidative shear treatments used by fiber manufacturers are not effective on higher modulus fibers that have fewer edge and defect sites in the surface crystallites. In addition, sizings commercially supplied on most carbon fibers are not compatible with polyimides. This study was an extension of prior work characterizing the surface chemistry and energy of high modulus carbon fibers (M40J and M60J, Torray) with typical fluorinated polyimide resins, such as PMR-II-50. A continuous desizing system which utilizes environmentally friendly chemical- mechanical processes was developed for tow level fiber and the processes were optimized based on weight loss behavior, surface elemental composition (XPS) and morphology (FE-SEM) analyses, and residual tow strength of the fiber, and the similar approaches have been applied on carbon fabrics. Both desized and further treated with a reactive finish were investigated for the composite reinforcement. The effects of desizing and/or subsequent surface retreatment on carbon fiber on composite properties and performance including fiber-matrix interfacial mechanical properties, thermal properties and blistering onset behavior will be discussed in this presentation.

Allred, Ronald E.↗

NASA NTRS1971

Refrigerated cutting tools improve machining of superalloys

Freon-12 applied to tool cutting edge evaporates quickly, leaves no residue, and permits higher cutting rate than with conventional coolants. This technique increases cutting rate on Rene-41 threefold and improves finish of machined surface.

Dudley, G. M.↗

NASA NTRS1985

Innovative research in the design and operation of large telescopes for space: Aspects of giant telescopes in space

The capability and understanding of how to finish the reflector surfaces needed for large space telescopes is discussed. The technology for making very light glass substrates for mirrors is described. Other areas of development are in wide field imaging design for very fast primaries, in data analysis and retrieval methods for astronomical images, and in methods for making large area closely packed mosaics of solid state array detectors.

Angel, J. R. P.↗

NASA NTRS1988

Erosion-Resistant Water-Blast Nozzle

Design of nozzle reduces erosion of orifice by turbulent high-pressure water flowing through it. Improved performance and resistance to erosion achieved by giving interior nozzle surface long, gradual convergence before exit orifice abrupt divergence after orifice and by machining surface to smooth finish.

Roberts, Marion L.↗

NASA NTRS2001

Solid Lubrication Fundamentals and Applications: Abrasion: Plowing and Cutting - Chapter 5

Chapter 5 discusses abrasion, a common wear phenomenon of great economic importance. It has been estimated that 50% of the wear encountered in industry is due to abrasion. Also, it is the mechanism involved in the finishing of many surfaces. Experiments are described to help in understanding the complex abrasion process and in predicting friction and wear behavior in plowing and/or cutting. These experimental modelings and measurements used a single spherical pin (asperity) and a single wedge pin (asperity). Other two-body and three-body abrasion studies used hard abrasive particles.

Miyoshi, Kazuhisa↗

NASA NTRS2015

Low Cost, Upper Stage-Class Propulsion

The low cost, upper stage-class propulsion (LCUSP) element will develop a high strength copper alloy additive manufacturing (AM) process as well as critical components for an upper stage-class propulsion system that will be demonstrated with testing. As manufacturing technologies have matured, it now appears possible to build all the major components and subsystems of an upper stage-class rocket engine for substantially less money and much faster than traditionally done. However, several enabling technologies must be developed before that can happen. This activity will address these technologies and demonstrate the concept by designing, manufacturing, and testing the critical components of a rocket engine. The processes developed and materials' property data will be transitioned to industry upon completion of the activity. Technologies to enable the concept are AM copper alloy process development, AM post-processing finishing to minimize surface roughness, AM material deposition on existing copper alloy substrate, and materials characterization.

Vickers, John↗

DOE OSTI2022

Additive manufacturing of complex objects using refractory matrix materials

A method for the manufacture of a three-dimensional object using a refractory matrix material is provided. The method includes the additive manufacture of a green body from a powder-based refractory matrix material followed by densification via chemical vapor infiltration (CVI). The refractory matrix material can be a refractory ceramic (e.g., silicon carbide, zirconium carbide, or graphite) or a refractory metal (e.g., molybdenum or tungsten). In one embodiment, the matrix material is deposited according to a binder-jet printing process to produce a green body having a complex geometry. The CVI process increases its density, provides a hermetic seal, and yields an object with mechanical integrity. The residual binder content dissociates and is removed from the green body prior to the start of the CVI process as temperatures increase in the CVI reactor. The CVI process selective deposits a fully dense coating on all internal and external surfaces of the finished object.

Terrani, Kurt A.↗

DOE OSTI2024

Additive manufacturing of complex objects using refractory matrix materials

Terrani, Kurt A.↗

NASA NTRS1994

Neutral Ion Figuring of Chemical Vapor Deposited SiC

Ion figuring of optical components is a relatively new technology that can alleviate some of the problems associated with traditional contact polishing. Because the technique is noncontacting, edge distortions and rib structure print through do not occur. This investigation was aimed at determining the effect of ion figuring on surface roughness of previously polished or ductile ground ceramic optical samples. This is the first step in research directed toward the combination of a prefinishing process (ductile grinding or polishing) with ion figuring to produce finished ceramic mirrors. Multiple, chemical vapor deposited silicon carbide (CVD SiC) samples were polished or ductile ground to specular or near-specular roughness. These samples were then characterized to determine topographic surface information. The surface evaluation consisted of stylus profilometry, interferometry, and optical and scanning electron microscopy. The surfaces were then ion machined to depths from 0 to 5 micron. The finished surfaces were characterized to evaluate the effects of the ion-machining process with respect to the previous processing methods and the preexisting subsurface damage. This study provides some of the information required to effectively utilize a combined ductile grinding or polishing with ion machining as a procedure for figuring optical components.

Fawcett, Steven C.↗

NASA NTRS1997

ETP-0474: Evaluation of Electroless Nickel Coatings to Achieve Interference Fit in the RSRM Without Fretting

Part of the redesign of the SRMs for the Space Shuttle involved the substitution of three new capture cylinders for three of the previously used cylinders. These new cylinders mate with the old standard case segments in each of the three field joints. The new capture cylinders contain an integral capture latch on the tang end which mates with a case clevis during stackup at KSC. The capture cylinders also contain a groove in the capture latch to provide for a third 0-ring in the joint and are designed to achieve a metal-to- metal interference fit between the capture latch and the mating clevis. An unexpected fretting problem has occurred on the tang capture feature and the inner clevis leg interference fit surfaces on flight hardware since STS-26. Varying degrees of fretting damage have been found on the case segments from different flight motors. Fretting is a wear phenomena that occurs when two tightly fitting metal surfaces are subject to cyclic relative motion of extremely small amplitudes (generally less than 0.010-inch) in the absence of adequate lubrication. It is adhesive ("cold" - welding) in nature and vibration is its essential causative factor. This problem has manifested itself on the flight motors as a series of pits and axial gouges on the inside diameter (ID) surfaces of the inner clevis legs and the outside diameter (OD) surfaces of the tang capture features. The problem occurs in varying degrees of severity in all of the field joints. It is not believed that fretting is a flight safety issue. However, it could become a reusability issue if left unattended. Fretting has been encountered in other industries for many years and measures that will prevent or reduce it have been devised. These include: elimination or reduction of vibration (amplitudes and/or frequencies), elimination of slip, improved lubrication between parts, increased surface separation, increased interference, inducing residual compressive stresses in the surfaces of the mating parts, and employing non-fretting interference shims. Looking at each of these separately; vibration and slip occur in varying degrees and magnitudes in the field joints (as part of the roll-out, launch, flight, splashdown, flotation, and/or tow back) and are difficult to define or eliminate. Improved lubrication is something that was evaluated since it would be the simplest change to incorporate, but little or no improvement was found. Increasing surface separation would defeat the purpose of the interference fit. The effect of increasing the interference fit is unknown. Additional shot peening and/or surface rolling to impart residual compressive stresses in the joints undoubtedly would alter the characteristics and finish of the sealing surfaces of the motor cases. Also, experimental data' indicate that the tangs and clevises already have residual compressive stress fields on their surfaces yet fretting occurs. These stresses probably result from the case machining and the glass beading used to clean these surfaces.

Schaffnit, William O.↗

NASA NTRS1991

Fabrication Of Lightweight Mirrors Via CVD

New chemical-vapor deposition (CVD) process developed for fabricating lightweight Si/SiC mirrors. Process involves three CVD steps: to produce faceplate of mirror; to form lightweight back structure deposited integrally with faceplate; and to deposit layer of optical-grade material onto front surface of faceplate. Figure and finish of mirror fabricated into this latter material. Produces dense, highly pure polycrystalline materials polished to surface figures of high precision and finish.

Goela, Jitendra S.↗

NASA NTRS2007

Diamond Smoothing Tools

Diamond smoothing tools have been proposed for use in conjunction with diamond cutting tools that are used in many finish-machining operations. Diamond machining (including finishing) is often used, for example, in fabrication of precise metal mirrors. A diamond smoothing tool according to the proposal would have a smooth spherical surface. For a given finish machining operation, the smoothing tool would be mounted next to the cutting tool. The smoothing tool would slide on the machined surface left behind by the cutting tool, plastically deforming the surface material and thereby reducing the roughness of the surface, closing microcracks and otherwise generally reducing or eliminating microscopic surface and subsurface defects, and increasing the microhardness of the surface layer. It has been estimated that if smoothing tools of this type were used in conjunction with cutting tools on sufficiently precise lathes, it would be possible to reduce the roughness of machined surfaces to as little as 3 nm. A tool according to the proposal would consist of a smoothing insert in a metal holder. The smoothing insert would be made from a diamond/metal functionally graded composite rod preform, which, in turn, would be made by sintering together a bulk single-crystal or polycrystalline diamond, a diamond powder, and a metallic alloy at high pressure. To form the spherical smoothing tip, the diamond end of the preform would be subjected to flat grinding, conical grinding, spherical grinding using diamond wheels, and finally spherical polishing and/or buffing using diamond powders. If the diamond were a single crystal, then it would be crystallographically oriented, relative to the machining motion, to minimize its wear and maximize its hardness. Spherically polished diamonds could also be useful for purposes other than smoothing in finish machining: They would likely also be suitable for use as heat-resistant, wear-resistant, unlubricated sliding-fit bearing inserts.

Voronov, Oleg↗

NASA NTRS1982

Feasibility of SPF/DB titanium sandwich for LFC wings

The feasibility of fabricating SPF/DB titanium structures of sufficient smoothness to be used for laminar flow wing surfaces was demonstrated. Two methods of fabricating panels which meet the surface smoothness criteria were demonstrated. The first consists of superplasticity forming/diffusion bonding a panel using steel dies, then machining the surface to the required flatness and finish after forming. This approach, however, was estimated to be more costly than the second approach, in which the panel is formed against ceramic platens which produce the desired surface smoothness without subsequent finishing. Four panels were fabricated, and their surface quality was evaluated. The specified criteria for waviness compared with actual measured values on the panels is shown. The acceptable surface quality as well as feasibility of the laminar flow control surface design, in which separate strips incorporating the boundary layer bleed provisions are bonded into slots on the surface, was also demonstrated.

Mcquilkin, F. T.↗

DOE OSTI2023

Study of Cathode and Cavity Geometries in Electropolishing (EP): Electric Field Simulation

Niobium (Nb) superconducting radio frequency (SRF) cavities require electropolishing surface treatment to reach high acceleration gradient. EP performed in the plateau region of an I-V curve [1] leads to a smooth finish of the cavity surface including the equator surface. The equator surface is vital because a rough equator surface leads to premature quench and limit the cavity performance. Previous experimental work was performed to optimize EP parameters for low-beta (LB) 650 MHz Nb cavity [1]. It was found that different cathode surface areas vary the plateau onset voltage. A lower onset voltage was achieved for HB650 cavity with an enlarged cathode surface area. The aim of the study is to perform electrostatic and electrochemical simulation to understand the impact of both cavity geometry and cathodes. This report covers an initial result on electric field simulation performed with HB and LB 650 MHz cavities.

Loer, Bereket↗