Johnson, G. A. | Engineering Papers

NASA NTRS1989

Adhesion, friction, and wear of plasma-deposited thin silicon nitride films at temperatures to 700 C

The adhesion, friction, and wear behavior of silicon nitride films deposited by low- and high-frequency plasmas (30 kHz and 13.56 MHz) at various temperatures to 700 C in vacuum were examined. The results of the investigation indicated that the Si/N ratios were much greater for the films deposited at 13.56 MHz than for those deposited at 30 kHz. Amorphous silicon was present in both low- and high-frequency plasma-deposited silicon nitride films. However, more amorphous silicon occurred in the films deposited at 13.56 MHz than in those deposited at 30 kHz. Temperature significantly influenced adhesion, friction, and wear of the silicon nitride films. Wear occurred in the contact area at high temperature. The wear correlated with the increase in adhesion and friction for the low- and high-frequency plasma-deposited films above 600 and 500 C, respectively. The low- and high-frequency plasma-deposited thin silicon nitride films exhibited a capability for lubrication (low adhesion and friction) in vacuum at temperatures to 500 and 400 C, respectively.

Miyoshi, K.↗

NASA NTRS1988

Adhesion, friction, and wear of plasma-deposited thin silicon nitride films at temperatures to 700 C

The adhesion, friction, and wear behavior of silicon nitride films deposited by low- and high-frequency plasmas (30 kHz and 13.56 MHz) at various temperatures to 700 C in vacuum were examined. The results of the investigation indicated that the Si/N ratios were much greater for the films deposited at 13.56 MHz than for those deposited at 30 kHz. Amorphous silicon was present in both low- and high-frequency plasma-deposited silicon nitride films. However, more amorphous silicon occurred in the films deposited at 13.56 MHz than in those deposited at 30 kHz. Temperature significantly influenced adhesion, friction, and wear of the silicon nitride films. Wear occurred in the contact area at high temperature. The wear correlated with the increase in adhesion and friction for the low- and high-frequency plasma-deposited films above 600 and 500 C, respectively. The low- and high-frequency plasma-deposited thin silicon nitride films exhibited a capability for lubrication (low adhesion and friction) in vacuum at temperatures to 500 and 400 C, respectively.

Miyoshi, K.↗

NASA NTRS1985

The role of mock-ups in the development of Orbital Replaceable Units (ORU)

Orbital Replaceable Units (ORU) is defined as any unit designed for replacement while in orbit. Two types are given. The number of ORU and the ratio of types is given as a function of the particular spacecraft. The purpose of the study is to develop and validate hardware design and operations for on orbit replacement of large modular ORU's. Two types of of testing are outlined; 1-G tests and neutral buoyancy tests.

Johnson, G. A.↗

NASA NTRS1983

Development of aircraft lavatory compartments with improved fire resistance characteristics. Phase 4: Sandwich panel decorative ink development

Five chemically different resin systems with improved fire resistance properties were studied for a possible screenprinting ink application. Fire resistance is hereby defined as the cured ink possessing improvements in flammability, smoke emission, and thermal stability. The developed ink is for application to polyvinyl fluoride film. Only clear inks without pigments were considered. Five formulations were evaluated compared with KC4900 clear acrylic ink, which was used as a baseline. The tests used in the screening evaluation included viscosity, smoke and toxic gas emission, limiting oxygen index (LOI), and polyvinyl fluoride film (PVF) printability. A chlorofluorocarbon resin (FPC461) was selected for optimization studies. The parameters for optimization included screenprinting process performance, quality of coating, and flammability of screenprinted 0.051-mm (0.002-in.) white Tedlar. The quality of the screenprinted coating on Tedlar is dependent on viscosity, curing time, adhesion to polyvinyl fluoride film, drying time (both inscreen and as an applied film), and silk screen mesh material and porosity.

Jayarajan, A.↗

NASA NTRS1982

Development of a new low cost antireflective coating technique for solar cells

The goal of this study was the development of an antireflective (AR) coating technique that has the potential for high throughput and low cost yet is capable of producing films of good optical quality. Previous efforts to develop sprayed AR coatings had utilized titanium isopropoxide mixed with volatile solvents. These films worked well on smooth surfaces but when applied to etched semi-crystalline silicon surfaces yielded inconsistent results with more than 20 percent of the AM1 incident light being reflected. In this program titanium isopropoxide was sprayed directly onto heater wafers (410 C) to produce a uniform AR coating even on highly textured surfaces. Tests on various types of solar cells yielded performance improvements for the hot sprayed AR cells that are equivalent to that observed for evaporated TiOx AR coated cells. As an extension of this effort a new double layer AR consisting of a bottom layer of hot sprayed titanium isopropoxide and a top layer of hot sprayed aluminum isopropoxide in methylene chloride has resulted in more than 10 percent improvement in cell output as compared to a single layer AR cell.

Wohlgemuth, J. H.↗

NASA NTRS1979

Conference on Fire Resistant Materials: A compilation of presentations and papers

The proceedings of the NASA IRE Resistant Materials Engineering (FIREMEN) Program held at Boeing Commercial Airplane Company, Seattle, Washington, on March 1-2, 1979 are reported. The conference was to discuss the results of research by the National Aeronautics and Space Administration in the field of aircraft fire safety and fire-resistant materials. The program topics include the following: (1) large-scale testing; (2) fire toxicology; (3) polymeric materials; and (4) fire modeling.

Kourtides, D. A.↗

NASA NTRS1979

FIREMEN program

An overview of the program to improve fire retardant interior panels is presented. The sandwich panel makeup for different components, and the burn test results are presented.

Anderson, R. A.↗

NASA NTRS1979

Development of aircraft lavatory compartments with improved fire resistance characteristics. Phase 2: Sandwich panel resin system development

A NASA-funded program is described which aims to develop a resin system for use in the construction of lavatory wall panels, sidewall panels, and ceiling panels possessing flammability, smoke and gas emission, and toxicity (FS&T) characteristics superior to the existing epoxy resin. Candidate resins studied were phenolic, polyimide, and bismaleimide. Based on the results of a series of FS&T as well as mechanical and aesthetic property tests, a phenolic resin was chosen as the superior material. Material and process specifications covering the phenolic resin based materials were prepared and a method of rating sandwich panel performance was developed.

Anderson, R. A.↗

NASA NTRS1978

Development of aircraft lavatory compartments with improved fire resistance characteristics

The Boeing's participation in a NASA-funded program (FIREMEN) included developing materials for use as lavatory wall panels, sidewall panels, and ceiling panels possessing flammability, smoke, and toxicity (FS&T) characteristics superior to current materials of construction is described. A sandwich panel system is developed for improving FS&T characteristics and acceptable cost, processing requirements, aesthetic qualities, abrasion resistance, strain resistance, scuff resistance, and washability.

Anderson, R. A.↗

NASA NTRS1978

Development of aircraft lavatory compartments with improved fire resistance characteristics, phase 1: Fire containment test of a wide body aircraft lavatory module

A test was conducted to evaluate the fire containment characteristics of a Boeing 747 lavatory module. Results showed that the fire was contained within the lavatory during the 30-minute test period with the door closed. The resistance of the lavatory wall and ceiling panels and general lavatory construction to burn-through under the test conditions was demonstrated.

Anderson, R. A.↗

NASA NTRS1977

Aircraft interior sandwich panel development

Three resin systems (bismaleimide, polyimide and modified phenolic) and several decorative films for use in aircraft interior panelling were subjected to flammability, smoke and gas emission, and toxicity testing. Cost, weight and appearance were also taken into account in assessing the feasibility of the materials for applications in passenger seating areas as well as in unoccupied compartments (galleys, lavatories, closets). Heat release studies and burn-through tests provided an additional measure of the fire safety characteristics of the panelling. A modified phenolic resin system and Tedlar-polycarbonate decorative film were selected as the most promising candidates for replacing conventional epoxy resin-impregnated fiberglass materials.

Anderson, R. A.↗