Discussion on the Method of Measuring Modulus of Molecules and Metal Films by Bubble Method

Discussion on the Method of Measuring the Young's Modulus of Polymers and Metal Films by Bubble Method YAN Xinhua, REN Fengzhang, ZHOU Genshu, XU Kewei, ZHAO Wenji (The key point of metal material strength of Xi’an Jiaotong University. The tested sample was placed in the sample holder and the screws were tightened. Solid, gasket sealed.Apply air pressure from one side of the membrane through the air-blowing device, the size is measured by the Pressure Sensor, resolution lkPa.Maximum measurement rangeIMPa.Deflection of the film center is measured by infrared laser displacement sensor. Resolution 2|jim.Data Computer processing.

Bubbling. P is the loading pressure, R is the radius of the spherical cap, a is the radius of the circular hole, and ft is the central deflection of the film (bulging height). Let a be the film loading stress, s the strain to the film thickness, according to the mechanical balance conditions have received the first draft date: 2001-06-11: received revised date: 2001-10-29 Fund Project: National Natural Science Foundation of China Project Funding (59831040 and 59931010) Rare Metal Materials and Engineering 32 rolls The intercept and slope of this line can be obtained from the residual stress in the film a. and the 2D elastic modulus F. When the residual stress is compressive, the film is relaxed. The state of wrinkles and the state of mechanics are relatively complex. At present, there is no suitable mechanical model.

2.3 Sample preparation 2.3.1 Macromolecule film sample Heart-cutting concentric rounding, circular zigzag diameter range of 3mm ~ 7mm. Smooth the substrate with sandpaper, acetone cleaning; the thickness of 55pm commercial plastic tape paper ( Polyarylether) is stretched onto the substrate. Eight samples are prepared for each aperture. Sample preparation process diagram.

The schematic diagram of the spherical cap substitutes the pressure P and the deflection ft value measured in the experiment into (l), and (2) can be used to obtain the stress and strain values. When the material is in the linear elastic state, the pressure-deflection relationship is here: F=*/(:1-v), which is the two-dimensional elastic modulus. * is the one-dimensional elastic modulus, ie Young's modulus is Poisson's ratio.

2.2.2 When the separation membrane is under tension or relaxation, the separation membrane is in a state of no stress and flatness. In most cases, there is residual stress in the membrane and the membrane is in crease (residual compressive stress) or in tension (residual tensile stress). When the film is in the tensioned flat state, the expression of the loading stress in the film remains unchanged, and the strain e of the film is the sum of the residual strain and the external strain. At this time, the equation u) is still applicable. If it is still assumed that the material is in a linear elastic state, the pressure-burning relationship is: As can be seen from (7), jP//i and /i2 follow a linear relationship. From 2.3.2 metal film (nickel film) sample special metal substrate pretreatment with a special method, placed in the electroplating solution nickel plating. Plating solution pH = 4, r = 328K, current density / = 4A/dm2. After the completion of the removal, the entire media H (6mmX4mm) was peeled off from the substrate. A nickel film having a film thickness of 10, 15, 20, and 25 μm, respectively, was stretched and attached to the pretreated steel substrate. Prepare 8 samples for each film thickness, and the substrate diameter is 5mm. 3 Experimental results and analysis 3.1 Polymer film samples In this experiment, the polymer film was under tension, and the ball under tension in the separation film was used. The crown model calculates the elastic modulus of the film. The typical P-ft curve for a polymer film at different pore sizes is the corresponding p/ft-/ curve. Because the measurement accuracy of the deflection in the small deformation region is relatively low, and the deformation of the film in the large deformation region has deviated from the linear elasticity, the two parts of the data are not given. As can be seen from the figure, the polymer film-/I2 curve is basically linear, and the slope (8Yf/3a4) decreases as the aperture increases. The y-axis intercept (4f"./a2) is a quantity related to the residual stress. Since the polymer film is artificially attached, only the residual stress is tensile stress, but the size is not necessarily the same, so its cut The distribution of the distance has no obvious regularity, which is the curve of the polymer film under different pore sizes.It can be seen that after removing the influence of the pore size, the fitting slope (8Ff/3) of the curves at different pore sizes is basically the same, ie, the polymer at different pore sizes. The elastic modulus of the film is maintained for a period of 4 years, Xinhua Xin et al.: Method of measurement of the elastic modulus of macromolecules and metallic films by the bubbling method is discussed 315, indicating that the aperture has no effect on the measurement of the elastic modulus of the film. According to formula (7), The two-dimensional elastic modulus of the polyaryl ether film is calculated to be 2.7*0.2 GPa. The Young's modulus of this polymer film is reported to be 1.8 GPa, and when the Poisson's ratio is 0.42, the two-dimensional elastic modulus is 3 This polymer film was modified to obtain a dense two-dimensional elastic modulus of 6.84*0.77 GPa and a porous type of 3.53*0.7 GPa. This experimental result is compared with the reported results. Low, the difference may come from two aspects First, the thickness of the polyarylether film used in this experiment is one order of magnitude higher than the thickness of the film in the experiment. Second, the tape made of polyaryl ether film is used in this experiment. Adhesive adhesive is on the back of the film. The elastic modulus of the polyaryl ether films was reduced, and the data obtained in this experiment was very good in terms of stability and repeatability, and the rules were also very strong.

The PA curve of the polymer film at different pore sizes 3.2 Nickel film sample is the typical ft curve of the nickel film. It can be seen that the measurement data of the nickel film is relatively scattered, and the curve is fit to the equation (6). The R2 is only 0.90. Other measurements of the nickel film are also dispersive, and the fitting curves are all less than 0. 92. The calculated two-dimensional elastic modulus of the nickel film is 269*65 GPa, and the dispersion is quite large. The two-dimensional elastic modulus of the nickel bulk material is quite different by 329±15 GPa. Therefore, this measurement data cannot be used to calculate the elastic modulus of the nickel film. The elastic modulus of the nickel film is more than 100 times larger than that of the polymer film. According to formula (3), it can be concluded that when the applied pressure P is the same, the higher the elastic modulus, the smaller the deflection ft of the film. For the polymer thin film and the nickel film, when the other initial conditions are the same, when the same pressure is applied, the flexibility ft of the polymer thin film is more than 100 times that of the nickel film. Bubbler displacement measurement accuracy is 2|Jim, less than 2|Jim can't be measured. In the middle, when the pressure changes in a certain range, the deflection does not change, only when the deflection accumulates more than 2|Jim. There will be changes in /i. P//iV Curves for Polymer Films at Different Pore Sizes Wmm 7 p-curves for towns and membranes Rare Metal Materials and Engineering Volume 32 This developed bubbler can be used to measure thin films with low elastic modulus, such as high Molecular films, in their current state, are difficult to measure thin films with high elastic modulus, such as metal films.

4 Conclusions 1) The 2-D elastic modulus of the polyaryl ether film measured by the bubbling method was 2.7*0.2 GPa, and the aperture had no effect on the measurement of the film's elastic modulus.

2) In order to apply the bubbler to measure the elastic modulus of the metal film, the displacement measurement accuracy must be further improved.