Investigating And Testing Materials Flashcards
How to test for abrasive wear in terms of the Hardness of a material?
Running a file over the material using the same force on each material sample - the one with the fewest sctraches is the most hardest
What is ultrasonic testing? States the benefits of this testing? Applications of use?
A transducer generates sound which travels into the material and reflects back to the signal generator. If there are any defects the waves that travel will partially refract and and will be shown on the display
It is portable and can be tested on any materials
Has a high accuracy of flaw detection
Used in aerospace or in the construction industry to detect any faults in strength of materials fused together under soldering pipes
What is x-ray testing? What can it be used for?
Used to observe tiny details in the material and can detect and hairline fractures within a material
It can be used to check for circuit boards and micro-voids in composite materials e.g. Formula 1
Used in aerospace as well
Electrical conductivity:
a four-point probe method can be used to determine the electrical conductivity of materials. Four small-diameter wires are stretched, parallel to each other across a non-conductive polymer block, held in place and connected to copper terminal blocks. Two leads are attached to the inner wires and two to the outer wires. The outer leads are connected to a precise current and the two inner leads measure the voltage drop. Ohm’s law (V=IR) can then be used to calculate the resistance of the material sample.
How to test for thermal conductivity
using a heat flow meter, a square-shaped material test piece is placed between two temperature controlled plates. The temperature is increased at a controlled rate and the heat flow through the material is measured by heat flow sensors placed on the surface of the material. As the material is heated to a specific temperature, the sensors measure and record the rate of thermal conductivity.
