Coefficient of Thermal Expansion

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Abstract

In this lab we attempted to identify various materials by calculating their density and then the Coefficient of Thermal Expansion or CTE of the samples. We completed this by first measuring the linear dimensions and then by cooling the samples to find the CTE expansion rate. We were able to determine the identity of 11 samples in this lab.

Purpose

The purpose of the lab was to identify the sample materials based on their density and CTE.

Materials and Methods

In the first part of the lab in order to determine the density, we first had to find the linear dimensions of each sample to calculate their volume. We used a digital caliper to measure the length, width and height of symmetrical samples and utilized water displacement to measure the volume of irregular samples.

In the second part of the lab, we sought to determine the CTE of each sample. To do this we first measured the samples length using a micrometer to a tolerance of .0001 of an inch. Once the measurements were complete we utilized dry ice to dramatically decrease the sample’s temperature. The samples were placed on the dry ice until they had a layer of frost on them. Since we did not have an accurate way of measuring the temperature of the sample we just estimated them at -100°F. Once the layer of frost was present we picked up the samples opposite the sides we measured from and quickly wiped off the frost and the re-measured the samples using the micrometers. At this point we now had the initial measurement and the final measurement and we then could figure out the CTE by using the following formula;

CTE= ΔL/Lᴵ/Δ°F
CTE=.0003/.7987/175
CTE=.0000021

Data and Results

Below are the graphs for Density and CTE based off the calculations on the following pages which have the actual data collected and calculated.

Conclusion

From this lab we were able to determine what types of materials we were testing by using the reference data sheet that was given to us and...
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