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Scratch Resistance of Cellphone Screen Protectors
Scratch Resistance of Cellphone Screen Protectors
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Importance of Testing Screen Protectors
Although phone screens are designed to resist shattering and scratching, they are still susceptible to damage. Daily phone usage causes them to wear and tear, e.g. accumulate scratches and cracks. Since repairing these screens can be expensive, screen protectors are an affordable damage prevention item commonly purchased and used to increase a screen’s durability.
Using the Nanovea PB1000 Mechanical Tester’s Macro Module in conjunction with the acoustic emissions (AE) sensor, we can clearly identify critical loads at which screen protectors show failure due to scratch1 testing to create a comparative study between two types of screen protectors.
Two common types of screen protector materials are TPU (thermoplastic polyurethane) and tempered glass. Of the two, tempered glass is considered the best as it provides better impact and scratch protection. However, it is also the most expensive. TPU screen protectors on the other hand, are less expensive and a popular choice for consumers who prefer plastic screen protectors. Since screen protectors are designed to absorb scratches and impacts and are usually made of materials with brittle properties, controlled scratch testing paired with in-situ AE detection is an optimal test setup for determining the loads at which cohesive failures (e.g. cracking, chipping and fracture) and/or adhesive failures (e.g. delamination and spallation) occur.
Measurement Objective
In this study, three scratch tests were performed on two different commercial screen protectors using Nanovea’s PB1000 Mechanical Tester’s Macro Module. By using an acoustic emissions sensor and optical microscope, the critical loads at which each screen protector showed failure(s) were identified.
Test Procedure and Procedures
The Nanovea PB1000 Mechanical Tester was used to test two screen protectors applied onto a phone screen and clamped down to a friction sensor table. The test parameters for all scratches are tabulated in Table 1 below.
Results and Discussion
Because the screen protectors were made of a different material, they each exhibited varying types of failures. Only one critical failure was observed for the TPU screen protector whereas the tempered glass screen protector exhibited two. The results for each sample are shown in Table 2 below. Critical load #1 is defined as the load at which the screen protectors started to show signs of cohesive failure under the microscope. Critical load #2 is defined by the first peak change seen in the acoustic emissions graph data.
For the TPU screen protector, Critical load #2 correlates to the location along with the scratch where the protector began to visibly peel off the phone screen. A scratch appeared on the surface of the phone screen once Critical load #2 was surpassed for the remainder of the scratch tests. For the Tempered Glass screen protector, Critical load #1 correlates to the location where radial fractures began to appear. Critical load #2 happens towards the end of the scratch at higher loads. The acoustic emission is a larger magnitude than the TPU screen protector, however, no damage was done to the phone screen. In both cases, Critical load #2 corresponded to a large change in depth, indicating the indenter had pierced through the screen protector.
Conclusion
In this study we showcase the Nanovea PB1000 Mechanical Tester’s ability to perform controlled and repeat-able scratch tests and simultaneously use acoustic emission detection to accurately identify the loads at which adhesive and cohesive failure occur in screen protectors made of TPU and tempered glass. The experimental data presented in this document supports the initial assumption that Tempered Glass performs the best for scratch prevention on phone screens.
The Nanovea Mechanical Tester offers accurate and repeatable indentation, scratch, and wear measurement capabilities using ISO and ASTM compliant Nano and Micro modules. The Mechanical Tester is a complete system, making it the ideal solution for determining the full range of mechanical properties of thin or thick, soft or hard coatings, films, and substrates.
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Lubricating Eye Drop Comparison using the Nanovea T50 Tribometer
Importance of Testing Eye Drop Solutions
Eye drop solutions are used to alleviate symptoms caused by a range of eye problems. For example, they can be used to treat minor eye irritation (e.g. dryness and redness), delay the onset of glaucoma or treat infections. Eye drop solutions sold over-the-counter are mainly used to treat dryness. Their effectiveness in lubricating the eye can be compared and measured with a coefficient of friction test.
Dry eyes can be caused by a wide range of factors, for example, computer eye strain or being outdoors in extreme weather conditions. Good lubricating eye drops help maintain and supplement the moisture on the outer surface of the eyes. This works to alleviate the discomfort, burning or irritation and redness associated with dry eyes. By measuring the coefficient of friction (COF) of an eye drop solution, its lubricating efficiency and how it compares to other solutions can be determined.
Measurement Objective
In this study, the coefficient of friction (COF) of three different lubricating eye drop solutions was measured using the pin-on-disk setup on the Nanovea T50 Tribometer.
Test Procedure and Procedures
A 6mm diameter spherical pin made of alumina was applied to a glass slide with each eye drop solution acting as the lubricant between the two surfaces. The test parameters used for all experiments are summarized in Table 1 below.
Results and Discussion
The maximum, minimum, and average coefficient of friction values for the three different eye drop solutions tested are tabulated in Table 2 below. The COF v. Revolutions graphs for each eye drop solution are depicted in Figures 2-4. The COF during each test remained relatively constant for most of the total test duration. Sample A had the lowest average COF indicating it had the best lubrication properties.
Conclusion
In this study we showcase the capability of the Nanovea T50 Tribometer in measuring the coefficient of friction of three eye drop solutions. Based on these values, we show that Sample A had a lower coefficient of friction and therefore exhibits better lubrication in comparison to the other two samples.
Nanovea Tribometers offers precise and repeatable wear and friction testing using ISO and ASTM compliant rotative and linear modules. It also provides optional high temperature wear, lubrication, and tribo-corrosion modules available in one pre-integrated system. Such versatility allows users to better simulate the real application environment and improve fundamental understanding of the wear mechanism and tribological characteristics of various materials.
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Multi Scratch Automation of Similar Samples using the PB1000 Mechanical Tester
Introduction :
Coatings are widely used in various industries because of their functional properties. A coating’s hardness, erosion resistance, low friction, and high wear resistance are just some of the many properties that make coatings important. A commonly used method to quantify these properties is scratch testing, this allows for a repeatable measurement of a coating’s adhesive and/or cohesive properties. By comparing the critical loads at which failure occurs, the intrinsic properties of a coating can be evaluated.
Comparing Abrasion Wear on Denim
Introduction
The form and function of a fabric is determined by its quality and durability. Daily usage of fabrics cause wear and tear on the material, e.g. piling, fuzzing, and discoloration. Subpar fabric quality used for clothing can often lead to consumer dissatisfaction and brand damage.
Attempting to quantify the mechanical properties of fabrics can pose many challenges. The yarn structure and even the factory in which it was produced can result in poor reproducibility of test results. Making it difficult to compare test results from different laboratories. Measuring the wear performance of fabrics is critical to the manufacturers, distributors, and retailers in the textile production chain. A well controlled and reproducible wear resistance measurement is crucial to ensure reliable quality control of the fabric.
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Rotative or Linear Wear & COF? (A Comprehensive Study Using the Nanovea Tribometer)
Wear is the process of removal and deformation of material on a surface as a result of the mechanical action of the opposite surface. It is influenced by a variety of factors, including unidirectional sliding, rolling, speed, temperature, and many others. The study of wear, tribology, spans many disciplines, from physics and chemistry to mechanical engineering and material science. The complex nature of wear requires isolated studies toward specific wear mechanisms or processes, such as adhesive wear, abrasive wear, surface fatigue, fretting wear, and erosive wear. However, “Industrial Wear” commonly involves multiple wear mechanisms occurring in synergy.
Linear reciprocating and Rotative (Pin on Disk) wear tests are two widely used ASTM-compliant setups for measuring sliding wear behaviors of materials. Since the wear rate value of any wear test method is often used to predict the relative ranking of material combinations, it is extremely important to confirm the repeatability of the wear rate measured using different test setups. This enables users to carefully consider the wear rate value reported in the literature, which is critical in understanding the tribological characteristics of materials.
Nano Mechanical Characterization of Spring Constants
A spring’s ability to store mechanical energy has a long history of use. From bows for hunting to locks for doors, spring technology has been around for many centuries. Nowadays we rely on springs, be it from mattresses, pens, or automotive suspension, as they play a vital role in our daily lives. With such a wide variety of use and designs, the ability to quantify their mechanical properties is necessary.
High Speed Characterization of an Oyster Shell
Large samples with complex geometries can prove difficult to work with due to sample preparation, size, sharp angles, and curvature. In this study an oyster shell will be scanned to demonstrate the Nanovea HS2000 Line Sensor’s capability to scan a large, biological sample with complex geometry. While a biological sample was used in this study, the same concepts can be applied to other samples.
Mechanical Broadview Map Selection Tool
We’ve all heard the term, time is money. Which is why many companies constantly seek methods of expediting and improving various processes, it saves time. When it comes to indentation testing, speed, efficiency and precision can be integrated into a quality control or R&D process when using one of our Nanovea Mechanical Testers. In this application note, we will be showcasing an easy way of saving time with our Nanovea Mechanical Tester and Broad View Map and Selection Tool software features.
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Surface Finish Inspection of Wood Flooring
Importance of Profiling Wood Finishes
In various industries, the purpose of a wood finish is to protect the wooden surface from various types of damage such as chemical, mechanical or biological and/or provide a specific visual aesthetic. For manufacturers and buyers alike, quantifying surface characteristics of their wood finishes can be vital to the quality control or optimization of finishing processes for wood. In this application, we will explore the various surface features that can be quantified using a Nanovea 3D Non-Contact Profilometer.
Quantifying the amount of roughness and texture that exists on a wooden surface can be essential to know in order to ensure it can meet the requirements of its application. Refining the finishing process or checking the quality of wooden surfaces based on a quantifiable, repeatable and reliable surface inspection method would allow manufacturers to create controlled surface treatments and buyers the ability to inspect and select wood materials to meet their needs.
Measurement Objective
In this study, the high-speed Nanovea HS2000 profilometer equipped with a non-contact profiling line sensor was used to measure and compare the surface finish of three flooring samples: Antique Birch Hardwood, Courtship Grey Oak, and Santos Mahogany flooring. We showcase the capability of the Nanovea Non-Con-tact Profilometer in delivering both speed and precision when measuring three types of surface areas and a comprehensive in-depth analysis of the scans.
Test Procedure and Procedures
Results and Discussion
Sample description: Courtship Grey Oak and Santos Mahogany flooring are laminate flooring types. Courtship Grey Oak is a low gloss, textured slate gray sample with an EIR finish. Santos Mahogany is a high gloss, dark burgundy sample that was prefinished. Antique Birch Hardwood has a 7-layer aluminum oxide finish, providing everyday wear and tear protection.
Antique Birch Hardwood
Courtship Grey Oak
Santos Mahogany
Discussion
There is a clear distinction between all the samples’ Sa value. The smoothest was Antique Birch Hardwood with a Sa of 1.716 µm, followed by Santos Mahogany with a Sa of 2.388 µm, and significantly increasing for Courtship Grey Oak with a Sa of 11.17 µm. P-values and R-values are also common roughness values that can be used to assess the roughness of specific profiles along the surface. The Courtship Grey Oak possess-es a coarse texture full of crack-like features along the wood’s cellular and fiber direction. Additional analysis was done on the Courtship Grey Oak sample because of its textured surface. On the Courtship Grey Oak sample, slices were used to separate and calculate the depth and volume of the cracks from the flatter uniform surface.
Conclusion
In this application, we have shown how the Nanovea HS2000 high-speed profilometer can be used to inspect the surface finish of wood samples effectively and efficiently. Surface finish measurements can prove to be important to both manufactures and consumers of hardwood flooring in understanding how they can improve a manufacturing process or choose the appropriate product that performs best for a specific application.
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Precise Localized Glass Transition with Nanoindentation DMA
Precise Localized Glass Transition with Nanoindentation DMA
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Imagine a scenario where a bulk sample is uniformly heated at a constant rate. As a bulk material heats up and approaches its melting point, it will start to lose its rigidity. If periodic indentations (hardness tests) are conducted at the same target force, the depth of each indent should be constantly increasing since the sample is becoming softer (see figure 1). This continues until the sample begins to melt. At this point, a large increase in the depth per indent will be observed. Using this concept, phase change in a material can be observed by using dynamic oscillations with a fixed force amplitude and measuring its displacement, i.e. Dynamic Mechanical Analysis (DMA).
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Stress Relaxation Measurement using Nanoindentation
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