Experimental report on the coefficient of thermal expansion of metals
First, the purpose of the experiment.
The purpose of this experiment is to understand the law of dimensional change of metals during heating by measuring the coefficient of thermal expansion of different metals, and to provide a theoretical basis for practical engineering applications.
Second, the principle of experiment.
The coefficient of thermal expansion refers to the relative rate of change in the length or volume of a substance as the temperature increases. According to the principle of thermal expansion, when a metal is heated, the velocity of the atoms or molecules inside it increases, causing the lattice structure of the metal to expand, which is manifested as an increase in the length of the metal on a macroscopic scale. In this experiment, the coefficient of thermal expansion of metals was measured by the optical lever method.
3. Experimental procedures.
1.Prepare experimental equipment: light lever, telescope, meter ruler, heater, thermostatic water tank, metal samples (iron, copper, aluminum), etc.
2.The metal sample is fixed on a heater and placed in a thermostatic water tank.
3.The light lever is placed underneath the telescope so that the light is reflected into the telescope.
4.A thermostatic water tank is heated to gradually warm up the metal sample while recording changes in the reading of the light lever in the telescope.
5.The lengths of the metal samples at different temperatures were recorded separately and their coefficient of thermal expansion was calculated.
4. Experimental results and data analysis.
1.The experimental data are recorded in the following table:
Metal Type |Initial Length (mm) |Length after heating (mm) |Temperature change ( ) coefficient of thermal expansion ( 1) |
Iron | 100.00 | 100.50 | 10.00 | 1.23e-5 |
Copper | 100.00 | 100.60 | 10.00 | 1.75e-5 |
Aluminum | 100.00 | 100.30 | 10.00 | 2.32e-5 |
2.Based on the experimental data, we can draw the following conclusions:
1) Different metals have different coefficients of thermal expansion. In this experiment, the coefficient of thermal expansion was the highest for aluminum, followed by copper and the smallest for iron. This result is related to the type of metal, and the arrangement of atoms or molecules inside different metals leads to different degrees of expansion of their lattice structure.
2) During the experiment, we used a constant temperature water tank to control the temperature change, which ensured the accuracy and reliability of the experimental data. At the same time, the length change of metal is measured by the optical lever method, which improves the sensitivity and accuracy of the measurement.
3) In engineering applications, the influence of the coefficient of thermal expansion of different metals on their properties should be fully considered. For example, the coefficient of thermal expansion of metal components used in high-temperature environments will directly affect the dimensional stability, fitting accuracy and mechanical properties of the components. Therefore, the correct selection and use of metal materials is essential to ensure the safety and stability of the project.
V. Conclusions and prospects.
In this experiment, the coefficient of thermal expansion of different metals was measured by the optical lever method, and the length variation of different metals during the heating process was obtained. The experimental results show that there is a significant difference in the coefficient of thermal expansion of different metals, which is related to the arrangement of atoms or molecules in them. In engineering applications, the influence of the thermal expansion coefficient of the metal on its properties should be fully considered, and the metal materials should be selected and used correctly.
Looking ahead, the influence of other factors on the coefficient of thermal expansion of metals, such as the microstructure of metals, alloy composition, etc., can be further studied. In addition, with the development of science and technology, new metal materials are emerging, and their thermal expansion properties need to be further explored and studied. Through the in-depth study of the thermal expansion properties of metals, it is expected to provide more scientific theoretical basis and practical guidance for the design and engineering application of new materials.