6. Processing and Characterization

Surface Engineering — Quiz

Test your understanding of surface engineering with 5 practice questions.

Practice Questions

Question 1

In electrochemical testing, the Stern–Geary equation relates corrosion current density $i_{corr}$ to polarization resistance $R_p$ and constant $B$ via $i_{corr}=B/R_p$. If $B=26\,\mathrm{mV}$ and $R_p=1000\,\Omega\cdot\mathrm{cm^2}$, what is $i_{corr}$ in $\mu\mathrm{A/cm^2}$?

Question 2

Using the corrosion rate formula $\mathrm{CR}=\frac{0.00327\,i_{corr}\,EW}{\rho}$ where CR is in mm/yr, $i_{corr}$ in $\mu$A/cm^2, $EW$ in g/equiv, and $\rho$ in g/cm^3, calculate the corrosion rate for iron with $i_{corr}=1.0\,\mu\mathrm{A/cm^2}$, $EW=27.92$ g/equiv, and $\rho=7.85$ g/cm^3.

Question 3

In thermal barrier coating systems, the primary thermally grown oxide (TGO) that forms at the bond coat/ceramic interface under high-temperature exposure is:

Question 4

Which crack morphology typically propagates parallel to the surface within the ceramic topcoat of a TBC under cyclic thermal loading, leading to spallation?

Question 5

In a duplex coating comprising an HVOF-deposited bond coat and an APS ceramic topcoat, the primary function of the metallic bond coat is to: