Preparing High Quality Turbine Airfol Mounts Quickly Using the PlanarMet 300 Planar Grinder

Ni-based superalloys are often used to fabricate turbine airfoils (Figure 1), which require high mechanical strength, corrosion resistance and creep deformation resistance. However, these three properties make sample preparation a difficult process. The use of a high-speed planar grinder for planar grinding helps to gain more successful material removal and the high daily volume requirements. This article presents solutions for preparing airfoil specimens made of Ni-based superalloys.

Turbine airfoil

Figure 1. Turbine airfoil

Preparation

Sectioning

Using a precision cutter is the best practice to section airfoils to minimize deformation. Sectioning was performed in the direction of the sample bulk so the coating was compressed, to reduce the odds of the coating breaking off the substrate. An abrasive saw with a superalloy wheel can be used when the airfoil is too big for a precision saw. The IsoMet™ 4000 or 5000 was used to section the airfoil with the following consumable; IsoCut™ Precision Blade CBN HC

Mounting

The SimpliMet XPS1 mounting press, was used to mount the airfoil in the EpoMet G mounting media.

Grinding and Polishing

Grinding of the airfoils specimens’ plane was achieved using the PlanarMet 300. Initial grinding with a 120 [P120] grit alumina stone results in a high removal of material in a reduced time period of operation, compared to using conventional SiC abrasive papers. The reduction ranges from 10 minutes to a little more than one minute. The parameters used are listed in Table 3.

Table 1. Grinding and Polishing Parameters

Grinding setting
Load 10 lbs [45 N] (six samples)
Cycle time 1:10min
Head RPM 150
Platen Complimentary
Wheel Type Aluminum oxide wheel, 120grit [P120]

Polishing was carried out using the Ecomet/AutoMet 300 with a 12 in [305 mm] platen (Figure 2). The samples were polished in three steps in a central force mode (Table 4 and Figure 3).

Surface finish after PlanarMet 300 at 5X.

Figure 2. Surface finish after PlanarMet 300 at 5X.

Surface finish after MasterMet™ colloidal silica polishing on ChemoMet™ at 20X.

Figure 3. Surface finish after MasterMet™ colloidal silica polishing on ChemoMet™ at 20X.

Table 2. 4-Step Method for Ni-based SuperAlloys using the PlanarMet™ 300 and EcoMet™/AutoMet™ 300

Surface Abrasive/Size Load – lbs [N]/Specimen Platen speed [rpm] Head speed [rpm] Relative rotation Time [min:sec]
Alumina Grinding Stone 120 [P120] grit 10 [50] Fixed 150 1:10
UltraPadTM 9 µm MetaDiTM Supreme Diamond* 10 [50] 150 60 5:00
TriDentTM 3 µm MetaDi Supreme Diamond* 10 [50] 150 60 5:00
ChemoMetTM 0.02- 0.06 µm MasterMetTM Colloidal Silica 10 [50] 150 60 2:00

= Platen
= Specimen Holder
*Plus MetaDi Fluid Extender as desired

Imaging and Analysis

A Nikon Eclipse MA200 inverted microscope provided a 3.1 MP uEye digital microscopy camera was utilized to inspect the prepared specimens. The inspection was achieved with bright field illumination (BF). Figures 4 and 5 show BF micrographs of the airfoil etched with molybdic acid reagent.

Airfoil etched with Molybdic Acid Reagent at 5X.

Figure 4. Airfoil etched with Molybdic Acid Reagent at 5X.

Airfoil etched with Molybdic Acid Reagent at 50X.

Figure 5. Airfoil etched with Molybdic Acid Reagent at 50X.

Conclusion

A clear depiction of Ni-based superalloys can be gained in a rapid and quick manner by employing PlanarMet 300 Planar Grinder and advanced preparation techniques. The total processing time is shortened by 41% in comparison with conventional methods that use several steps of SiC grinding paper.

This information has been sourced, reviewed and adapted from materials provided by Buehler.

For more information on this source, please visit Buehler.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Buehler. (2019, July 13). Preparing High Quality Turbine Airfol Mounts Quickly Using the PlanarMet 300 Planar Grinder. AZoM. Retrieved on October 22, 2019 from https://www.azom.com/article.aspx?ArticleID=12601.

  • MLA

    Buehler. "Preparing High Quality Turbine Airfol Mounts Quickly Using the PlanarMet 300 Planar Grinder". AZoM. 22 October 2019. <https://www.azom.com/article.aspx?ArticleID=12601>.

  • Chicago

    Buehler. "Preparing High Quality Turbine Airfol Mounts Quickly Using the PlanarMet 300 Planar Grinder". AZoM. https://www.azom.com/article.aspx?ArticleID=12601. (accessed October 22, 2019).

  • Harvard

    Buehler. 2019. Preparing High Quality Turbine Airfol Mounts Quickly Using the PlanarMet 300 Planar Grinder. AZoM, viewed 22 October 2019, https://www.azom.com/article.aspx?ArticleID=12601.

Ask A Question

Do you have a question you'd like to ask regarding this article?

Leave your feedback
Submit