This paper describes a process of production of high-quality aluminum-filled epoxy replica mirrors using a glass master in a two-step process. From photometric data using a circle-of-confusion tester, optical data is given which evaluates the performance of these mirrors, cast by different methods and subjected to various environmental conditions. The data indicate that the mirrors can undergo significant thermal shock, thermal cycling, nuclear radiation, and change in moisture content without being severely degraded. Results of research on some of the physical properties of polymerized epoxy resins, which are pertinent in design and application of the mirrors, are presented.
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Epoxy used is Epon 828; catalyst is metaphenylenediamine; “cured” refers to second-stage cure at 70°C.
Density is by volume-mass method. (For conversion one gm/cc=0.03613 lb/in3).
Room-temperature value. Damping (Q−1) is by transverse-vibration method.20Q−1=Δf/f0 where f0 is the resonant frequency and Δf is the half-power width in cycles per second. For damping values which are not too large, this is related to the logarithmic decrement, δ, by δ=πQ−1.
Dynamic modulus is by transverse vibration method where the modulus and geometry determine the resonant frequency.20 These are room-temperature values.
Table VIII
Ultimate tensile strength (psi) of a series of irradiated and unirradiated epoxy mixtures.
Values in above table are based on original cross-sectional area. Series “a” were irradiated (PSU) for 20 000 sec (see irradiation data).
Samples cured at 70°C. All samples previously room curved (see text).
Values marked in this manner have large limits of error.
Table IX
Irradiation data for epoxy samplesa of Table VIII.
Reactor power level
100 kw
Irradiation time
20 000 sec or 5 hr, 33 min
Position
Horizontal centerline of maximum flux, 1.5 in. from core face
Thermal neutron flux
5×1012 neutrons/cm2-sec
Thermal neutron dose (total)
1.0×1016 neutrons/cm2 (nvt)
Gamma dose rate
5.5×106 r/hr
Gamma dose (total)
30×106 r
Tables (9)
Table I
Photometric optical performance of replica mirror while cooling from 73°C.
Detector aperture (inches)
Percent of reflected energy through detector aperture while mirror is cooling
41°–32°C
32°–30°C
29°–26°C
26°–25°C
0.010
97
96
94
91
0.009
91
96
91
90
0.008
88
92
90
90
0.005
80
88
89
88
0.004
74
85
82
86
Table II
Photometric optical performance of glass mirror while cooling from 73°C.
Detector aperture (inches)
Percent of reflected energy through detector aperture while mirror is cooling
45°–42°C
45°–37°C
37°–34°C
34°–30°C
24°–23°C
0.010
93
96
96
94
94
0.009
93
91
92
88
92
0.008
81
82
80
82
80
0.005
75
72
73
71
75
0.004
70
69
67
69
69
Table III
Photometric optical performance of glass mirror before and after heating to 73°C.
Percent of reflected energy through detector aperture
Detector aperture (inches)
Mirror before Heating to 73 °C
Mirror at room temperature after heating to 73°C
0.010
98
94
0.009
95
92
0.008
94
80
0.005
89
75
0.004
77
69
Table IV
Photometric optical performance of replica mirror before and after heating.
Percent of reflected energy through detector aperture
Detector aperture (inches)
First measurement at room temperature
After heating to 73°C and cooling to room temperature
After heating to 99°C and cooling to room temperature
0.010
89
91
90
0.009
89
90
90
0.008
86
90
85
0.005
84
88
82
0.004
73
86
73
Table V
Photometric optical performance of replica mirror over extended period of time.
Percent of reflected energy through detector aperture at given age
Detector aperture (inches)
0
2 hr
42 hr
13 days
15 days
43 days
Soaked in
of water
Baked in oven at 73°C for 30 hr
0.010
98%
89
89
91
93
89
87
90
0.009
88
88
88
89
90
87
87
88
0.008
86
86
87
88
88
86
84
86
0.005
74
76
79
77
77
83
79
73
0.004
59
65
67
59
59
73
71
55
Table VI
Comparison of photometric optical performance of replica mirrors with commercial glass mirrors.
Comparison of glass mirrors with filled-epoxy replica
Detector aperture
Commercial glass mirrors f/0.9, 6-in. diameter
Glass master f/9.9, 6-in. diameter
Filled- epoxy replica
#1
#2
#3
#4
#5
0.010
98
100
100
98
95
96
89
0.009
97
98
96
95
91
94
89
0.008
93
93
95
94
87
91
86
0.005
73
83
93
89
80
85
84
0.004
61
67
90
77
67
68
73
Table VII
Average values for density, damping, and dynamic modules of epoxy mixtures.
Epoxy used is Epon 828; catalyst is metaphenylenediamine; “cured” refers to second-stage cure at 70°C.
Density is by volume-mass method. (For conversion one gm/cc=0.03613 lb/in3).
Room-temperature value. Damping (Q−1) is by transverse-vibration method.20Q−1=Δf/f0 where f0 is the resonant frequency and Δf is the half-power width in cycles per second. For damping values which are not too large, this is related to the logarithmic decrement, δ, by δ=πQ−1.
Dynamic modulus is by transverse vibration method where the modulus and geometry determine the resonant frequency.20 These are room-temperature values.
Table VIII
Ultimate tensile strength (psi) of a series of irradiated and unirradiated epoxy mixtures.
Values in above table are based on original cross-sectional area. Series “a” were irradiated (PSU) for 20 000 sec (see irradiation data).
Samples cured at 70°C. All samples previously room curved (see text).
Values marked in this manner have large limits of error.
Table IX
Irradiation data for epoxy samplesa of Table VIII.
Reactor power level
100 kw
Irradiation time
20 000 sec or 5 hr, 33 min
Position
Horizontal centerline of maximum flux, 1.5 in. from core face
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