1、N76-11253 EVALUATION OF LOW COST/HIGH TEMPERATURE INSULATION Em Lm STRAUSS MARTIN MARIETTA AEROSPACE DENVER, COLORADO NOVEMBER 1975 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-.- NASA CR-134902 I EVALUATION OF LOW COST/HIGH TEMPERATURE INSULATION
2、 by E. L. Straust MARTIN MARIETTA AEROSPACE Denver, Colorado November 1975 prepared for NATIONAL AERONAUTICS AND SPACE ADMINISTRATION NASA Lewis Research Center Contract NAS3-18900 _. -. REPOOCED 1 . NATIONAL TECHNICAL INFORMATION SERVICE I,. S. DEPARTMENT OF COMMERCE SPRINGFIELD, VA. 22161 Provided
3、 by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NOTICE THIS DOCUM.ENT HAS BEEN REPRODUCED FROM THE BEST COPY FURNISHED US BY THE SPONSORING AGENCY. ALTHOUGH IT IS RECOGNIZED THAT CERTAIN PORTIONS ARE ILLEGIBLE, IT IS BEING RELEASED IN THE INTEREST OF MAKING
4、AVAILABLE - - AS MUCH INFORMATION AS POSSIBLE. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-1. Report No. 2. Government Accession No. CR- 134902 4. Title and Subtitle EVALUATION OF LOW COST/HIGH TEMPERATURE INSULATION 3. Recipients Catalog No. 5.
5、Report Date 6. Performing Organization Code November 1975 Martin Marietta Aerospace 1 P.O. Box 179 7. Author(s1 E. L. Strauss 9. Performing Organization Name and Address I 11. Contract or Grant No. 8. Performing Organization Report No. XCR 75-262 10. Work Unit No. I Denver, Colorado 80201 NAS3-18900
6、 I 12. Sponsoring Agency Name and Address National Aeronautics and Space Administration Washington, D.C. 20546 13. Type of Report and Period Covered Contractor Report July 1974 to June 1975 14. Sponsoring Agency Code I 15. Supplementary Notes Project Manager - John P. Merutka, Materials and Structur
7、es Division NASA Lewis Research Center, Cleveland, Ohio 44135 16. Abstract Six fiber products and six insulation blankets comprising silica, alumina, zirconia, mullite, and mixed ceramic systems were subjected to furnace exposures up to 500 hours at temperatures of 1000“ to 1600C and evaluated for c
8、hemical and dimensional stability and for changes in thermal conduc- tivity. Alumina, zirconia, and mullite fibers were fabricated into Reusable Surface Insulation (RSI) tile by water-felting and reimpregnation with ethyl silicate. Specimens were exposed to 25 thermal cycles at 12OOOC and 14OOOC and
9、 a pressure of 10 and 32 torr, respectively. Production costs for 930 m2 (10,000 ft2) of blanket insulation and of alumina RSI tile were developed. 19. Security Classif. (of this report) Unclassified -I_- 18 Distribution Statement -1- - .-_ 17 Key Words (Suggested by AuthorW) Ceramic Fibers Felted F
10、iber Cakes insuiation ij idrinets High Temperature Insulation Reusable Surface Insulation 20. Security Classif. (of this page) Unclassified For sale by the National Technical Information Service, Springfield. Virginia 22151 NASA-C-I68 (Rev. 6-71) Provided by IHSNot for ResaleNo reproduction or netwo
11、rking permitted without license from IHS-,-,-FOREWORD This report was prepared by the Denver Division, Martin Marietta Aerospace under Contract NAS3-18900 for the Lewis Research Center, National Aeronautics and Space Administration. The work was ad- ministered under the direction of the Lewis Resear
12、ch Centers Materials and Structures Division with Mr. John P. Merutka acting as Project Manager. The program was conducted by the Structures and Materials Depart- ment of the Engineering, Research and Technology organization during the period from 25 June 1974 to 30 June 1975. Mr. Eric L. Strauss of
13、 Martin Marietta Aerospace was the Program Manager and was also responsible for its technical direction. ii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-CONTENTS .- . SUMMARY I . INTRODUCTION . I1 . FIBER AND BLANKET MATERIALS rn I11 . A . B* . C
14、. IV . A . . B . C . D . V . EXPERIMENTAL PROCEDURES . FIBER CAKES AND BLANKETS . Furnace Exposure . Specimen Configuration Visual Observations SPECIMEN MEASUREMENTS AND MATERIAL CHARACTERIZATION . Weight. Dimensional and.Density Changes Scanning Electron Microscopy . X-Ray Diffraction . Room Temper
15、ature Thermal Conductivity . INDIVIDUAL FIBER CAKE AND BLANKET PERFORMANCE SUMMARY VI . EXPERIMENTAL PROCEDURES AND TESTING . RSI . VI1 . RSI TEST RESULTS . A . Weight. Dimensional and Density Changes B . Scanning Electron Microscopy . C . X-Ray Diffraction . D . Flexural Properties F . Individual R
16、SI Performance Summary E . Room Temperature Thermal Conductivity . 1 thru 5 6 7 and 8 9 9 10 10 11 11 12 12 13 and 14 15 thru 19 20 thru 23 24 24 24 24 25 25 25 and 26 iii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-VI11 . FABRICATION COST ANALYS
17、IS e . IX . SUMMARY OF RESULTS A . Fiber Cakes B . Blanket Haterials . C . RSI Materials . D . Fabrication Cost Analysis . X . A . B . CONCLUSIONS AND RECOMI4ENDATIONS Conclusions Recommendations XI . REFERENCES . . . 1 2 3 4 5 6 7 8 9 io 11 12 13 14 15 APPENDIX A FIGURE APPENDIX B TABLE . . . Figur
18、e . SEM photograph (1150X) of Irish Refrasil fibers SEM photograph (330X) of Fiberfrax H fibers showing shot content . SEN photograph (1040X) of Saffil Alumina HT fibers . SEM photograph (1040X) of Saffil Zirconia HT fibers . SEN photograph (320X) of B Task I1 - RSI Tile Manufacture, Thermal Exposur
19、e, and Evaluation. 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-II. FIBER AND BLANKET MATERIALS Six oxide fiber products and six blanket insulation systems were procured for this program. Table 1 describes the 12 materials and their suppliers an
20、d unit costs. Additional data on the materials systems are contained in vendor data (refs. 1 through 6). The materials range from fully commerical sys tern (Fiberf rax H, Microquartz, Fiberchrome, Kaowoal) to new commercial fibers (Saffil Alumina and Zirconia HT) , to experimental fibers (Mullite, I
21、rish Refrasil type SS-19-A5). Fiber diameter and shot content of the six fiber products were determined by scanning electron microscopy at magnification of approximately 330X and lOOOX, using a Cambridge high-resolution SEM unit. The fiber samples were gold-plated to accentuate the individual fibers
22、 and shot particles. Representative SEM photo- graphs are shown in Figures 1 through 6. The photographs show an uniform fiber diameter for Irish Refrasil, Saffil Alumina HT, and Saffil Zirconia HT. Fiberfrax H and the Mullite samples show a wide dispersion of fiber diameters. observed in the Irish R
23、efrasil and Saffil Alumina HT samples and only a single isolated shot particle was noted in Saffil Zirconia HT. Fiberfrax H and the two Mullite materials contained signifi- cant shot concentrations. A summary of fiber diameter and shot content data is presented in Table 2. No shot particles were To
24、facilitate furnace testing of the fiber products, water-felted fiber cakes were produced. Thermal testing of the fiber cakes would indicate the suitability of the fibers for use in reusable surface insulation systems. The target density for the fiber cakes was 0.12 g/cc (7.5 lb/ft3), which would pro
25、duce a 0.15 g/cc (9 lb/ft3) SI tile after addition of a binder. fiber bundles were dispersed and cleaned by using the technique described in NASA Tech Brief B73-10438 (ref. 7). Fiber clumps that were still held together by mechanical interlocking or by electrical charges were further dispersed by bl
26、ending with dis- tilled water in a Hobart mixer for 30 minutes. The amount of water used was lOC0 cc per 25 g of fibers. Separan AP 30 defloc- culating agent (ref. 8) was added to the water in a concentration of 0.05%. To dissolve Separan AP 30, the water was heated to near its boiling point and Sep
27、aran AP 30 was added slowly, while the water was stirred vigorously. To felt 3 Micron Mullite fiber cakes, the alkalinity of the Separan AP 30 water solution was raised to pii-i2 by addition of NHOti. Before felting, Fiber cakes were felted to a thickness of approximately 2.54 cm (1 in.) in a rectan
28、gular 15.2x6.4 cm (62% in.) felting rig equipped with a close fittlng plunger. Excess water was drained from the felts by vacuum aspiration. After removal from the felting rig, the fiber cakes were dried at 65C (150F) in a circulating air oven 7 Provided by IHSNot for ResaleNo reproduction or networ
29、king permitted without license from IHS-,-,-Densities of the Irish Refrasil, Saffil Alumina HT, Saffil Zirconia HT, and B and (2) a natural gas-fired kiln of 1538C (2800F) peak temperature and a 94x99 cm (37x39 in.) interior floor size. The electric kiln was an ECS furnace of 1510C (2750F) peak temp
30、erature and a 30x46 cm (12x18 in.) interior floor size. Individual fiber cakes and blankets were exposed for time periods listed in Table 3. The 3 Micron Nullite fibers, Saffil Alumina HT blanket, and Saffil Zirconia HT blanket were received after the start of furnace testing. The 3 Micron Mullite f
31、iber cakes were introduced into the test sequence at 25 hours into the 1400C gas- fired furnace run. Exposure data of 1000 and 1200C for this material were obtained in the 100-hour electric kiln runs. The Saffil Alumina HT blanket was introduced into the test sequence at the beginning of the 1200C g
32、as-fired furnace run. exposure data were obtained in the 100-hour elzctric kiln TU;:. The Saffil Zirconia HT blanket was introduced into the test se- quence at 75 hours into the 1200C gas-fired furnace run and measured after exposures of 25 and 425 hours. The 100-hour expo- sure data at 1000C and 12
33、00C were obtained in electric kiln runs. The Saffil Alumina and Zirconia HT blankets were laboratory- produced samples supplied by IC1 United States, Inc. After The 1000C 9 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-completion of the test sequen
34、ce, 10 lb each of a production lot of alumina and zirconia blanket were delivered. These materials were evaluated and compared with the earlier blanket samples by testing for 25 hours at 1400C in the electric kiln. The two material. lots were found to be equivalent. Irish Refrasil fiber cake, Fiberf
35、rax H blanket and Microquartz blanket were not tested beyond 100 hours at 1200C since visual examination indicated that these materials would be unsuitable for more severe exposures. Irish Refrasil suffered extensive loss of chromia while Fiberfrax H and Microquartz blankets be- came rigid and defor
36、med. SPECIMEN CONFIGURATIONS Three types of specimens were tested. They were 15.2x6.4x2.5 cm (622x1 in.) densityfshrinkage samples, 6.4x3.2x2.5 cm (22xl specimens are difficult to measure and the tabulated dimensional change data are therefore not precise. Since the deformation in these materials ca
37、n be affected by furnace gradients and heating rates, the blanket materials were retested in the electric kiln. Fiberchrome blanket was also retested at 1000C and Kaowool 1400 was retested at 1000 and 1200C in the electric kiln to determine the reproducibility of dimensional and weight change data f
38、or materials that remain flexible, flat, and square. Dimensional and weight change data of samples heated in the gas-fired and the electric kilns are compared in Table 23. Dimensional changes as determined in the two furnaces differed significantly for Fiber- frax H and Microquartz (materials which
39、hardened and deformed), but differed by lesser amounts for the Kaowool 1400 and Fiber- chrome samples that remained flat and square. Twisted 11 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Tables 24 through 27 categorize the temperature-exposed fi
40、ber cakes and blanket materials by percent weight loss and dimensional change into three categories : 1) Increase or 0 to 2X decrease; 2) 2 to 6/! Jecresse; 3) Greater than 6% decrease. These summary charts are for 500 hours of exposure. Where speci- mens had been exposed for only 100 hours, the cla
41、ssification is based on an extrapolation to 500 hours. Note, however, that most materials had undergone a major portion of the measured change after 25 hours of exposure as illustrated by the plot of length change at 1200C (Fig. 23). 6. SCANNING ELECTRON MICROSCOPY Scanning electron micrographs at l
42、OOOX magnification were taken of controls and thermally exposed fiber cakes and blanket mater- ials. SEM observations are summarized in Table 28. Photomicro- graphs are shown in Figure 47 through 56. In summary, no changes were observed in fiber morphology after exposure to 100 or 500 hours at 1000C
43、. The 1200C exposure produced grain growth and fiber sintering in Saffil Alumina HT fiber cake (old fiber mater- ial) and some slight evidence of grain growth in Saffil Alumina HT blanket. Grain growth occurred in all fiber materials at 14OO0C, ranging from moderate (3 Micron Mullite, Fiberfrax fibe
44、r- cake, Kaowool, and Saffil Alumina HT Blanket), to severe with fiber sintering or embrittlement (Saffil Alumina HT fiber cake, Saffil Zirconia HT fiber cake. Fiberchrome blanket, and Saffil Zirconia HT blanket). Severe grain growth with fiber fusion, sintering or embrittlement was observed in all
45、materials after exposure at 160OOC. C. X-RAY DIFFRACTION X-Ray diffraction of controls and thermally exposed fiber cakes and blanket materials were obtained with a Norelco Model 12045 unit. Results are summarized in Table 29. Control samples Were generally noncrystalline or exhibited weak crystallin
46、e peaks (Saffil Alumina HT; B green color (chromia) completely faded after 350 hours at 1000C. Material was noncrystalline after 500 hours at 1000C but exhibited a strong crystobalite peak after 50 and 100 hours at 1200C. Crystobalite formation has been shown to cause dimensional distortion and crac
47、king in silica RSI tile. Consequently, Refrasil fiber cakes were not tested beyond 1200C. Thickness increase at 1200C. Saffil Alumina HT Fiber Cake - Apparent fiber sintering with large shrinkage, yielding a hard RSI-like material with a ceramic ring. Shrinkage was 4 to 6% at 1000C with little chang
48、e beyond 25 hours; material was rigid and bowed after 350 hours. at 120OOC; material had board-like consistency after 25 hours. Shrinkage was greater than 15% at 1400C; samples were rigid and bowed after 5 hours. the order of 25% and weight loss was about 3%. Large sample-to- sample variations in shrinkage at 1200“ and 1400C. Material readily absorbed vaporized chromia from Irish Refrasil and Fiber- chrome. Retest of a different fiber batch for 25 hours at 1400C yielded much lower weight loss and shrinkage values, indicating that the poor thermal stability
