TECHNICAL FIELD

The disclosure relates to material composition and porosity detection.

BACKGROUND

A ceramic matrix composite (CMC) includes ceramic fibers embedded in a ceramic matrix. CMCs may have desirable mechanical, physical, and chemical properties such as high fracture toughness, thermal shock resistance, and elongation resistance. CMCs may be used for a variety of applications such as gas turbine engines, brake discs, and the like. An example CMC is silicon carbide-fiber reinforced silicon carbide (SiC/SiC) composite.

The ceramic fibers and ceramic matrix of a CMC may not be evenly distributed throughout a CMC article, leading to spatial differences in CMC composition. Further, in some examples, a CMC may include unwanted porosity. For example, a first portion of a CMC article may have a different composition of ceramic fibers and matrix material than a second portion of the CMC article. The CMC article may further include a coating that has an uneven porosity or layer thickness.

SUMMARY

In some examples, the disclosure describes a method that includes causing, by a controller, a capacitance probe to subject a material to an electric signal. The method further includes determining, by the controller, a capacitance of the material and a porosity of the material based on the capacitance.

In some examples, the disclosure describes a method that includes causing, by a controller, a capacitance probe to subject a material to an electric signal having a frequency. The material includes at least a first constituent phase and a second constituent phase. The first constituent phase and the second constituent phase have substantially different dielectric constants at the frequency. The method further includes determining, by the controller, a capacitance of the material at the frequency and a relative phase composition of the first constituent phase and the second constituent phase based on the capacitance.

In some examples, the disclosure describes a method that includes causing, by a controller, a capacitance probe to subject a first material to a first electric signal. The method further includes determining, by the controller, a first capacitance of the first material. The method further includes causing, by the controller, the capacitance probe to subject the first material and a second material on the first material to a second electric signal. The method further includes determining, by the controller, a second capacitance of the first material and the second material, and a porosity of the second material based on the first capacitance and the second capacitance.

In some examples, the disclosure describes a method that includes causing, by a controller, a capacitance probe to subject a first material to a first electric signal having a frequency. The method further includes determining, by the controller, a first capacitance of the first material. The method further includes causing, by the controller, the capacitance probe to subject the first material and a second material on the first material to a second electric signal having the frequency. The second material includes at least a first constituent phase and a second constituent phase. The first constituent phase and the second constituent phase have substantially different dielectric constants at the frequency. The method further includes determining, by the controller, a second capacitance of the first material and the second material, and a relative phase composition of the first constituent phase and the second constituent phase based on the first capacitance and the second capacitance.

In some examples, the disclosure describes a system that includes a controller configured to cause a capacitance probe to subject a material to an electric signal, determine a capacitance of the material, and determine a porosity of the material based on the capacitance.

In some examples, the disclosure describes a system that includes a controller configured to cause a capacitance probe to subject a material to an electric signal at a frequency. The material includes at least a first constituent phase and a second constituent phase. The first constituent phase and the second constituent phase have substantially different dielectric constants at the frequency. The controller is further configured to determine a capacitance of the material and a relative phase composition of the first constituent phase and the second constituent phase based on the capacitance.

In some examples, the disclosure describes a system that includes a controller configured to cause a capacitance probe to subject a material to a first electric signal having a first frequency and determine a first capacitance of the material at the first frequency. The controller is configured to cause the capacitance probe to subject the material to a second electric signal at a second frequency and determine a second capacitance of the material at the second frequency. The material includes at least a first constituent phase and a second constituent phase. The first constituent phase and the second constituent phase have substantially similar dielectric constants at the first frequency and substantially different dielectric constants at the second frequency. The controller is further configured to determine a porosity of the material based on the first capacitance and determine a relative phase composition of the first constituent phase and the second constituent phase based on the second capacitance.

The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

