1768087
Description
Flashcards by cathy_shona, updated more than 1 year ago
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Created by cathy_shona
over 9 years ago
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| Question | Answer |
| General material response to temperature? | As the temperature increases materials expand, the elastic modulus decreases as well as strength upon approaching the m.p. One melted the material has lost all strength and stiffness. |
| Maximum Service Temperature | The maximum temperature a material can reach before risk of oxidation, chemical changes or excessive deformation. |
| Minimum Service Temperature | The minimum temperature before a material becomes unsafe to use or too brittle to handle. |
| Glass Transition Temperature | Temperature where the amplitude of vibration becomes so large that the VDW bonds become ineffective (amorphous) |
| Heat Capacity | The energy required to raise the temperature of 1kg of material by 1K. (J/kg. K) |
| Linear Thermal Expansion Coefficient | Measures the thermal strain per degree of temperature (K-1) |
| Thermal Conductivity | Measures the flow of heat through a solid material in a steady-state (W/m .K) |
| How do you measure Thermal Diffusivity? | can be calculated directly from the time taken for a known temperature pulse to travel a set thickness when the heat is applied briefly on one side. |
| What makes a good Heat Exchanger? | must be able to transfer heat and withstand internal pressure from the fluids. (high thermal conductivity and yield strength) |
| What makes a good insulator? | Minimize power loss (low thermal conductivity) |
| What is the objective for a Storage Heater? | store as much heat per unit cost as possible. (also consider Tmax) |
| What are the 3 processing families? | Shaping, Joining and Finishing |
| What are the lower limits of Casting and Moulding? | Section thickness imposed by the physics flow. lrg SA=heat loss= premature cooling and solidification. |
| How could you get very thin materials? | Either rolling or high pressure die-casting and molding methods. |
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