How do you perform a scratch test on materials?

A scratch test is a simple and widely used method to measure the hardness and adhesion of materials, such as coatings, films, or composites. It involves dragging a sharp tip across the surface of a material under a controlled load and observing the resulting damage. In this article, you will learn how to perform a scratch test on materials and what factors to consider for accurate and reliable results.

1 Prepare the sample and the tip

Before you start the scratch test, you need to prepare the sample and the tip. The sample should be clean, dry, and flat, and mounted on a rigid support. The tip should be made of a harder material than the sample, such as diamond, and have a well-defined geometry, such as a cone or a sphere. You also need to calibrate the tip to ensure that the applied load is consistent and accurate.

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Farhad Khorasani

Sales Manager at Mana Polymer
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**** **** 1. Select a Testing Tool: Choose an appropriate tool for the scratch test, such as a calibrated indenter or a testing machine with a known load. 2. Prepare the Material: Ensure the material surface is clean and flat. Polish if necessary to eliminate any irregularities that may affect the scratch test. 3. Apply Initial Load: Gradually apply the initial load to the testing tool, maintaining a constant force on the material surface. 4. Perform Scratch: Move the tool across the material surface, applying a consistent force. Observe any deformation, scratches, or changes in the material during this process. 5. Evaluate Results: Assess the scratch characteristics, including length, depth, and any visible damage. Compare the results.

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2 Set the test parameters

The next step is to set the test parameters, such as the scratch length, the scratch speed, and the load profile. The scratch length should be long enough to cover the entire thickness of the material or coating, but not too long to cause excessive wear on the tip. The scratch speed should be constant and moderate, to avoid thermal effects or vibrations. The load profile can be either constant or progressive, depending on the purpose of the test. A constant load can measure the critical load at which the material or coating fails, while a progressive load can measure the load range over which the material or coating resists damage.

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Zeeshan Hassan Saeed

Mechanical, Energy System Engineer|Energy Storage System| Nano Materials|Ambassador @Skills Quest | 6Sigma Certified| Graphic Designer| Blogger|
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In any test, parameters, constraints, variables are most important. Thus they play important role in identifying the unknown. Here for scratch test, variables are length, thickness, load applied, load range, material coating, etc. By defining the variable, and test tool we easily find unknowns., for example as said "constant load" can measure the critical load at which the material or coating fails., "progressive load" can measure the load range over which material fail. All the material designed for specific loads. Any mirror mistakes leading failure of martial for desired options.

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3 Perform the scratch and record the data

The third step is to perform the scratch and record the data. You need to align the tip with the sample and initiate the scratch at the desired load and speed. You also need to monitor the friction force, the acoustic emission, and the displacement of the tip during the scratch. These data can provide information about the onset and progression of damage, such as cracking, delamination, or spalling. You should also record the visual appearance of the scratch using a camera or a microscope.

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4 Analyze the data and the scratch

The final step is to analyze the data and the scratch. You need to plot the data as a function of the load or the scratch distance, and identify the critical points where the damage occurs. You can also calculate the hardness and the adhesion of the material or coating from the data, using empirical formulas or models. You should also examine the scratch morphology and depth, and compare them with the data and the expected behavior of the material or coating.

By following these steps, you can perform a scratch test on materials and obtain useful information about their mechanical properties and performance. A scratch test can help you evaluate the quality and durability of materials or coatings, as well as optimize their design and application.

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5 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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Dr. Dragos Petrescu

Executive, Investor, Entrepreneur • Renewables, Minerals, Infrastructure, Housing, Data Centres
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Performing a scratch test on materials involves subjecting a sample material to controlled scratching to evaluate its hardness & resistance to abrasion. General procedure involves: • Select Testing Equipment—calibrated hardness tester or a set of reference materials with known hardness values • Prepare the Sample—ensure sample material is clean & free from any surface contaminants • Apply Scratch—choose apply a controlled force to the surface of the material • Observe & Measure, and Record Results • Repeat Test • Analysis & Interpretation—compare observed scratch characteristics with reference materials or standards to evaluate material's performance • Reporting—document scratch test procedure, results, findings, & include relevant details.

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How do you perform a scratch test on materials?

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1 Prepare the sample and the tip

2 Set the test parameters

3 Perform the scratch and record the data

4 Analyze the data and the scratch

5 Here’s what else to consider

Materials Science

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