--- title: Solutions by Material Thermal Spray Coatings url: https://www.buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-thermal-spray-coatings/ date: 2024-05-01T17:06:42+00:00 modified: 2025-02-10T19:56:44+00:00 lang: en_US --- # Solutions by Material Thermal Spray Coatings Solutions By Materials: # Thermal Spray Coatings ## Metallographic Preparation Solutions by Material Use this guide for advice on where to start when performing metallographic preparation and analysis on thermal spray coatings. Included are tips for achieving the best results for your metallographic application. [![Sectioning Products Hexagon](https://buehler.com/wp-content/uploads/2023/04/Sectioning-Products-Hexagon.png)](#cutting) [Thermal Spray Coating Cutting](#cutting) [![Mounting Products Hexagon](https://buehler.com/wp-content/uploads/2023/04/Mounting-Products-Hexagon.png)](#mounting) [Thermal Spray Coating Mounting](#mounting) [![Grinding & Polishing Hexagon](https://buehler.com/wp-content/uploads/2023/04/Grinding-Polishing-Hexagon.png)](#gp) [Thermal Spray Coating Grinding & Polishing](#gp) [![Buehler Products Etching](https://buehler.com/wp-content/uploads/2023/04/Buehler-Products-Etching.png)](#etching) [Thermal Spray Coating Etching](#etching) [![Hardness Testing Hexagon](https://buehler.com/wp-content/uploads/2023/04/Hardness-Testing-Hexagon.png)](#hardness) [Thermal Spray Coating Hardness Testing](#hardness) ### Things to consider when working with Thermal Spray Coating (TSC) ![Things to consider when working with Thermal Spray Coating TSC](https://buehler.com/wp-content/uploads/2024/04/Things-to-consider-when-working-with-Thermal-Spray-Coating-TSC-1024x683.jpg) Thermal spray coatings typically consist of at least two parts, the coating, and the substrate beneath the coating. For metallurgical analysis, the coating itself and where it adheres to the substrate are the main focus. Components of the substrate and coating as well as the manufacturing process can differ. These differences can change the products used for sample preparation (blades, grinding, polishing, mounting method, etc.). With coatings often being the focus for analysis, it is important that internal structures are retained. Porosity, thickness, and adherence to the substrate are commonly examined. To preserve these characteristics samples are often mounted using epoxy systems prior to other preparation methods. Low-viscosity, castable systems are recommended with vacuum systems to mount the specimen. #### Thermal Spray Coating Cutting Tips ![Thermal Spray Coating Cutting Tips](https://buehler.com/wp-content/uploads/2024/04/Thermal-Spray-Coating-Cutting-TIps-1024x683.jpg) ![Thermal Spray Coating Cutting Tips](https://buehler.com/wp-content/uploads/2024/04/Thermal-Spray-Coating-Cutting-Tips_2-1024x683.jpg) Precision saws induce less damage in coatings than abrasive saws. When sectioning a thermal spray coating there are a few things to consider: - Composition - Orientation/Support - Structure To select a blade, it is important to know the material that makes up the sample. The blade used should be suitable for material that is more difficult to cut. [IsoCut® wafering blades](https://shop.buehler.com/isocut-hc-blade-7-x-025) are commonly employed, as coatings are sometimes deposited on nickel alloys or steel substrates. [Series 15 HC precision blades](https://shop.buehler.com/wafering-blde-7x025x12-15hc) may be used on metallic coatings such as titanium. Sectioning time and blade life are influenced by blade choice. The orientation of thermal spray coating when sectioning is important. Due to the ability of the coatings to delaminate or fracture, samples should be cut under compression. Ensure the blade is entering the coating and exiting through the substrate. The use of a [Double Saddle Chuck](https://shop.buehler.com/double-saddle-chuck-3) supports both sides of the cut which can improve cut quality. When clamping it's good practice to pad the chuck with a softer material. This can be done with small strips of polishing cloth adhered to the chucks clamping surface and ensures the ability to clamp firmly without damaging the coating. If the sample is porous, friable, or has multiple sides coated, mounting the sample before sectioning would help support the internal structures. #### Thermal Spray Coating Mounting Tips ![Thermal Spray Coating Mounting Tips](https://buehler.com/wp-content/uploads/2024/04/Thermal-Spray-Coating-Mounting-Tips-1024x683.jpg) A low-viscosity [epoxy system](https://buehler.com/products/mounting/mounting-consumables/epoxy-mounting-systems/) can fill gaps in the coating, helping to hold the internal structures. [EpoThin®](https://shop.buehler.com/epoxy-systems#/specFilters=15m!#-!244) is recommended for optimal edge retention and infiltration though this requires a nine hour cure time. If shorter times are required then [EpoKwick® FC](https://shop.buehler.com/epoxy-systems#/specFilters=15m!#-!545) is a good alternative by reducing the cure time to two hours. Cycling samples multiple times under vacuum greatly improves pore impregnation, optimizes sample adherence, and provides additional support for delicate thermal spray samples. The [SimpliVac](https://buehler.com/products/mounting/castable-mounting/simplivac-vacuum-mounting-system/) allows a user to pour under vacuum and automate the cycling process. We suggest using 25 inHg and going through 10 cycles of 60 seconds as demonstrated in [Improve Sample Quality by Running Multiple Cycles with SimpliVac](https://buehler.com/assets/solutions/technotes/Improve-Sample-Quality-by-Running-Multiple-Cycles-with-SimpliVac-Article.pdf) Article. Adding a dye to the epoxy will help distinguish between the sample and the pores. While there are always exceptions, hot compression mounting is generally not recommended for thermal spray coatings because high-pressure levels can cause damage to the coating's internal structure. #### Thermal Spray Coating Grinding & Polishing Tips for All Methods ![Thermal Spray Coating Grinding & Polishing Tips for All Methods](https://buehler.com/wp-content/uploads/2024/04/Thermal-Spray-Coating-Grinding-Polishing-Tips-for-all-methods-1024x683.jpg) Central force is recommended when preparing TSCs. [Central force specimen holders](https://shop.buehler.com/filterSearch?as=true&cid=0&q=central%20force&Sid=True&Isc=true) secure the sample in place within the holder for all grinding and polishing steps. Samples should be prepared under compression to reduce the chances of damaging the coating. To keep samples in compression orient coatings so abrasives cut through the coating first and then exit through the substrate. During polishing, the coating should push against and be supported by the substrate to reduce potential damage. Force is applied to the center and dispersed amongst the sample faces. Thoroughly clean samples between preparation steps. Porous samples are likely to pick up particles. Minimize contamination by putting samples in an ultrasonic bath between steps. Using Buehler's [Burst dispensing system](https://shop.buehler.com/burst-stadium-seating-module) can conserve diamonds and improve consistency. The ideal rate for the Burst dispensing system changes with the size of the platen and the polishing cloth that is being used. As a general guideline, for a platen size of 8” a burst setting of 3 is a good starting point, for sizes of 10" and 12" set the burst system to 4 and adjust as needed. Some experimentation may be required to determine optimal settings to ensure sufficient abrasive and wetting of the cloth. Burst dispensers are also capable of dispensing extenders simultaneously with diamond if desired. ![Burst Dispensing System](https://buehler.com/wp-content/uploads/2021/10/Burst_Stadium.png) Loads listed in grinding and polishing methods are recommendations for one 1.25" mounted specimen. If using central force during preparation the force listed should be multiplied by the number of samples being polished. For different sample sizes, use our [load conversion calculator](https://buehler.com/solutions/tools/) to determine the correct load for your application | 4-Step Method for Ceramic Thermal Spray Coatings | | | | | | --- | --- | --- | --- | --- | | Surface | Load lbs \[N\] | Base Speed \[rpm\] | Relative Rotation | Time | | [DGD Ultra (45-μm Diamond)](https://shop.buehler.com/ultra-prep-disc-8-45m-psa) | 5 \[22\] | 300 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | Until Plane | | [UltraPad](https://shop.buehler.com/ultra-pad-polish-cloth8psa) with [9um MetaDi Supreme Diamond](https://shop.buehler.com/metadi-supreme-poly-susp-9-mic-8oz) | 5 \[22\] | 200 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | 6:00 | | [TriDent](https://shop.buehler.com/trident-polish-cloth-8-psa) with [3um MetaDi Supreme Diamond](https://shop.buehler.com/metadi-supreme-poly-susp-3mic-8oz) | 6 \[27\] | 120 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | 5:00 | | [ChemoMet](https://shop.buehler.com/chemomet-for-8-in-wheel-psa) with [MasterMet Colloidal Silica](https://shop.buehler.com/mastermet-polishing-suspension) | 6 \[27\] | 120 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | 2:00 | | ![Platen](https://buehler.com/assets/solutions/platen.png) = Platen ![Specimen Holder](https://buehler.com/assets/solutions/Specimen-holder.png) = Specimen Holder \*Plus MetaDi Fluid Extender as desired | | | | | | 4-Step Method for Metallic Thermal Spray Coatings | | | | | | --- | --- | --- | --- | --- | | Surface | Load lbs \[N\] | Base Speed \[rpm\] | Relative Rotation | Time | | [DGD Color Yellow (35-μm Diamond)](https://shop.buehler.com/apex-metal-backed-dgd-yellow-35-u-8) | 6 \[27\] | 300 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | Until Plane | | [UltraPad](https://shop.buehler.com/ultra-pad-polish-cloth8psa) with [9um MetaDi® Supreme Diamond](https://shop.buehler.com/metadi-supreme-poly-susp-9-mic-8oz) | 6 \[27\] | 150 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | 4:00 | | [TriDent](https://shop.buehler.com/trident-polish-cloth-8-psa) with [3um MetaDi Supreme Diamond](https://shop.buehler.com/metadi-supreme-poly-susp-3mic-8oz) | 6 \[27\] | 150 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | 3:00 | | [ChemoMet®](https://shop.buehler.com/chemomet-for-8-in-wheel-psa) with [MasterMet® Colloidal Silica](https://shop.buehler.com/mastermet-polishing-suspension) | 4 \[18\] | 150 rpm | ![Relative Rotation](https://buehler.com/assets/solutions/Complimentary-Rotation.png) | 2:00 | | ![Platen](https://buehler.com/assets/solutions/platen.png) = Platen ![Specimen Holder](https://buehler.com/assets/solutions/Specimen-holder.png) = Specimen Holder \*Plus MetaDi Fluid Extender as desired | | | | | #### Thermal Spray Coating Etching Tips ![Thermal Spray Coating Etching Tips](https://buehler.com/wp-content/uploads/2024/04/Thermal-Spray-Coating-Etching-Tips-1024x683.jpg) To etch thermal spray coatings the composition must be known. Etching solutions should be chosen according to the composition of the coating. #### Thermal Spray Coating Imaging Tips ![Thermal Spray Coating Imaging Tips](https://buehler.com/wp-content/uploads/2024/04/Thermal-Spray-Coating-Imaging-Tips-1024x683.jpg) Common coatings analysis includes measurement of porosity, coating thickness, and defects in adhesion. All can be measured using our [OmniMet® software Advanced](https://buehler.com/products/imaging-and-analysis/software/omnimet-software-solutions/). Measurements, annotations, and percentage analysis can be determined for designated sample areas. #### Thermal Spray Coating Hardness Testing Tips ![Thermal Spray Coating Hardness Tips](https://buehler.com/wp-content/uploads/2024/04/Thermal-Spray-Coating-Hardness-Tips-1024x683.jpg) When the method of hardness testing is being decided on, the application is assessed to find the scale that fits the needs outlined. At Buehler, our equipment supports hardness testing using four scales: Brinell, Rockwell, Vickers, and Knoop. Depending on the sample and information required the scale needed can change. While working with spray coatings several factors could affect the ability to measure the indent. The surface finish of the specimen; flatness and scratches would hinder software auto-measuring indents. To reduce uneven surface finish, ensure that the samples are smooth before starting the polishing process. Coating geometries do not always allow for easy hardness testing. Selection of test area can be difficult because of pores and limited area to indent. When testing, if an indent lays over a pore, it could lead to an abnormally shaped indent and require re-testing in another location. Using Epoxy to support the coating structure can help reduce the likelihood of this happening. Indent tips may be hidden or obscured within pores and cracks. Ceramic coatings are especially susceptible to this. One way to abate these effects when indenting on a thermal spray coating is to use a lighter load. Lighter loads not only decrease the chances of cracking but also allow for the targeting of solid areas of coating material. Configure equipment with a 100x objective when measuring indents 20 microns or smaller. Good contrast is important with indent measurements when analyzing samples comprised of an undercoat and overcoat having different levels of reflectance. Adjust the lighting for each coating. [DiaMet Full-automatic](https://buehler.com/products/hardness-testing/automation-software/diamet-hardness-testing-software/) and up have settings to allow automated illumination, and focus. ![VH3300 with DiaMet](https://buehler.com/wp-content/uploads/2024/04/VH3300-with-DiaMet-1024x683.jpg) #### Related Products [![AbrasiMet M™ Manual Abrasive Cutter](https://buehler.com/wp-content/uploads/2021/08/AbrasiMet-M-3qtrs-open.png)](https://buehler.com/products/sectioning/abrasive-cutters/abrasimet-m-manual-abrasive-cutter/) ##### [AbrasiMet® M](https://buehler.com/products/sectioning/abrasive-cutters/abrasimet-m-manual-abrasive-cutter/) Abrasive Cutter [![Blades for Abrasive Cutters](https://buehler.com/wp-content/uploads/2021/08/premium-Abrasive-Cutter-Blades.png)](https://buehler.com/products/sectioning/sectioning-and-cutting-consumables/blades-for-abrasive-cutters/) ##### [Abrasive Blades](https://buehler.com/products/sectioning/sectioning-and-cutting-consumables/blades-for-abrasive-cutters/) Abrasive Blades for Abrasive Saws [![Hot Compression Mounting Compounds](https://buehler.com/wp-content/uploads/2023/12/Hot-Compression-Mounting-Image.png)](https://buehler.com/products/mounting/mounting-consumables/compression-mounting-powder-and-pre-molds/) ##### [EpoMet®](https://buehler.com/products/mounting/mounting-consumables/compression-mounting-powder-and-pre-molds/) Compression Mounting Compound [![Wilson® VH3300 Automatic Hardness Tester](https://buehler.com/wp-content/uploads/2021/10/VH3300_front-view_no-monitor.png)](https://buehler.com/products/hardness-testing/vickers-knoop-hardness-testers/wilson-vh3300-vickers-and-knoop-hardness-tester/) ##### [Wilson® VH3300](https://buehler.com/products/hardness-testing/vickers-knoop-hardness-testers/wilson-vh3300-vickers-and-knoop-hardness-tester/) Automated Hardness Tester ## All Solutions by Material Choose a material to view Buehler's resources - [Aluminum and Aluminum Alloys](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-aluminum-and-aluminum-alloys/ "Buehler's Method by Material Aluminum") - [Composites](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-composites/ "Buehler's Method by Material Composites") - [Copper and Copper Alloys](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-copper-and-copper-alloys/ "Buehler's Method by Material Copper") - [Electronic Components](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-electronic-components/ "Buehler's Method by Material Electronic Components") - [Stainless Steel](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-stainless-steel/ "Buehler's Method by Material Stainless Steels") - [Cast Iron](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-cast-iron/ "Buehler's Method by Material Cast Iron") - [Carbon Steels](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-carbon-steels/ "Buehler's Method by Material Carbon Steels") - [Nickel and Nickel Alloys](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-nickel-and-nickel-alloys/ "Buehler's Method by Material Nickel and Nickel Alloys") - [Printed Circuit Boards](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-printed-circuit-boards/ "Buehler's Method by Material Printed Circuit Boards") - [Thermal Spray Coatings](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-thermal-spray-coatings/ "Buehler's Method by Material Thermal Spray Coatings") - [Titanium and Titanium Alloys](https://buehler.com/solutions/buehler-solutions/solutions-by-material/solutions-by-material-titanium-and-titanium-alloys/ "Buehler's Method by Material Titanium and Titanium Alloys")