Assignment 6; solutions
1. What parameters of the electrodepositing process affect the formation of the texture?
Answer: The parameters of electrodeposition that influence changes in the surface free energy
change texture. Most often these are: plating current, over-potential, Ph of the solution,
temperature of the electrolyte, concentration of metal ions, structure of plating current (i.e pulse
plating)
2. Assume, you would like to electrodeposits nanocrystalline Ni film, what values (low or high)
you will recommend for the following parameters: a) addition agents like saccharine; b)
current density c) temperature; d) agitation
Answer: a) high; b) high; c) low; d) low
3. What properties are affected by texture in a) Zn based automobile coatings b) Cu films
Answer: a) corrosion resistance, paint adhesion, formability, bending.
Answer: b) line loss upon etching, hardness, oxidation and corrosion resistance.
4. High temperature oxidation of nickel electrodeposits are affected by texture of the substrate
and type of grain boundaries. Suggest possible explanation, and try to justify why certain grain
boundaries and crystallographic planes do not oxidize easily.
Answer: Oxidation in Ni is dominated by outward diffusion of metal ions. High angle grain
boundaries are faster pass for diffusion of ions than the low angle and CSL boundaries, therefore
they oxidize more strongly. Low oxidation resistance of planes is related to high packing density of
atoms and also surface free energy. Bulk diffusion in the direction that is perpendicular to (111)
high density plains is more difficult, and therefore these plains do not oxidize easily.
5. Young modulus of textured Fe sheet is measured at different angles (deg) with respect to the
rolling direction and is Y(0)=200 GPa ; Y(45)=120 GPa ; Y(90)=220 GPa ; Estimate approximate
𝟏𝟑
𝟏𝟐
values of 𝑪𝟏𝟏
𝟒 ; 𝑪𝟒 ; 𝑪𝟒 coefficients.
Answer: The coefficients 𝐶411 ; 𝐶412 ; 𝐶413 are proportional to 165 GPa, 10 GPa, and 45 GPa. The
coefficients do not have units. If the 𝐶411 is high this indicates that the texture is weak.