ASNT Level III- Visual & Optical Testing

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5.2 Silicone Rubber Replicas Silicone impression materials have been used extensively in medicine, dentistry and in the science of anthropology. In nondestructive testing, silicone materials are used as tools for documenting macroscopic and microscopic material detail. Quantitative measurements can be obtained for depth of pitting, wear, surface finish and fracture surface evaluation. Silicone material is made with varying viscosities, setting times and resolution capabilities. Compared to an acetate replica, the resolution characteristics of a silicone replica is limited. With a medium viscosity compound, fine features visible at 50 x can be resolved but difficulties are encountered at higher magnifications. With a low viscosity compound, slightly better resolution is obtained but curing times are long and not suited to field applications. The lower viscosity medium is also known to creep with time and is not recommended for applications where very accurate dimensional studies are needed. Charlie Chong/ Fion Zhang
5.2.1 Use of Silicone Replicating Materials Silicone replicating materials are supplied in two parts: a base material and an accelerator. Although it is best to follow the recommended mixing ratios, these can be altered slightly to change the working time of the material. The two parts are mixed thoroughly and spread over the subject area. Additional material can he added to thicken the replica. Molding clay can also be used to build a dam around a replicated area. The dam supports the replica as its sets and allows thicker replicas to be made. Measurements of pit depth and surface finish can be obtained easily because of the silicone's ability to flow into crevices on the test object. To evaluate pit depth and surface finish, the replica is cut and the cross section is examined with a microscope or a macroscopic measuring device (a micrometer or an optical comparator). Charlie Chong/ Fion Zhang
Page 1 and 2: ASNT Level III- Visual & Optical Te
Page 3 and 4: At works Charlie Chong/ Fion Zhang
Page 5 and 6: Charlie Chong/ Fion Zhang Fion Zhan
Page 7 and 8: SECTION 4: BASIC AIDS AND ACCESSORI
Page 9 and 10: PART 4: MACHINE VISION TECHNOLOGY 4
Page 11 and 12: PART 6: TEMPERATURE INDICATING MATE
Page 13 and 14: PART 4: MACHINE VISION TECHNOLOGY 1
Page 15 and 16: 5.1 Cellulose Acetate Replication A
Page 17 and 18: 5.1.2 Fracture Surface Analysis The
Page 19 and 20: Replicas, in the as-stripped condit
Page 21 and 22: Microstructural replication is done
Page 23 and 24: If analysis with the scanning elect
Page 25 and 26: Sputter deposition is a physical va
Page 27 and 28: Sputtering http://en.wikipedia.org/
Page 29 and 30: Sputtering http://clearmetalsinc.co
Page 31 and 32: Sputter Deposition Charlie Chong/ F
Page 33 and 34: 5.1.4 Strain Replication The replic
Page 35 and 36: FIGURE 56. Principles of acetate ta
Page 37 and 38: Fatigue striations Charlie Chong/ F
Page 39 and 40: FIGURE 59. Documentation of creep d
Page 41 and 42: FIGURE 60. Documentation of stress
Page 43 and 44: TABLE 14. Action required for creep
Page 45 and 46: Cellulose Acetate Replication http:
Page 47 and 48: Replication Microscopy Techniques f
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Page 53 and 54: FIGURE 63. Silicon replicas used to
Page 55 and 56: Brittle Failure Chevron Marking Cha
Page 57 and 58: PART 6: TEMPERATURE INDICATING MATE
Page 59 and 60: Temperature indicating sticks were
Page 61 and 62: Levels of Charlie Chong/ Fion Zhang
Page 63 and 64: 6.2 Certification of Temperature In
Page 65 and 66: 6.3 Applications for Temperature In
Page 67 and 68: 6.3.2 Verifying Oven Temperatures T
Page 69 and 70: 6.3.4 Process Control Applications
Page 71 and 72: 6.3.6 Precise Post forming Heat Con
Page 73 and 74: Another example of handforrning is
Page 75 and 76: 6.3.7 Pipeline Coatings Epoxy powde
Page 77 and 78: The most common use for temperature
Page 79 and 80: FIGURE 67. Temperature indicating s
Page 81 and 82: PART 7: CHEMICAL AIDS 7.0 General T
Page 83 and 84: 7.1 Test Object Selection Figure 68
Page 85 and 86: 7.2 Surface Preparation Preparation
Page 87 and 88: 7.2.2 Removing Rust and Scale Rust
Page 89 and 90: If the required finish cannot be ac
Page 91 and 92: FIGURE 70. Example of contrast reve
Page 93 and 94: 7.3.2 Safety Precautions Etchants a
Page 95 and 96: Etchant Safety Charlie Chong/ Fion
Page 97 and 98: Etchant Safety Charlie Chong/ Fion
Page 99 and 100: 7.3.3 Containers Containers used wi
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1. add the acid or alkali to the wa
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7.3.6 Disposal Before disposing of
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7.4.2 Swabbing Etching may also be
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7.4.4 Test Object Preservation Rins
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7.5 Conclusion Visual testing is pe
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Cellulose Replica Sheets Charlie Ch
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Charlie Chong/ Fion Zhang
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