Abstract: Modern testing equipment for mechanical properties of materials allows for highly precise
measurements of both hardness and the elasticity modulus. Advances in nanoindentation techniques, coupled
with sophisticated software, make it possible to generate detailed load and unload curves. In particular, the
area between the load and unload curves has been recognized as a new metric for evaluating the mechanical
characteristics of a material. This area quantifies the energy absorbed during the loading process and released
during unloading, which can be thought of as the 'workability' of the material. This term 'workability' is used
because the value is calculated based on the area between the two curves, represented on a plane where the
force (F) is plotted against the displacement of the indenter (d). The larger the area, the more work the material
undergoes during deformation, thus giving an indication of its mechanical robustness and durability under
stress.
In the study, titanium coatings were applied using a cold gas spraying technique to several different metal
substrates, including brass, steel, titanium, Al7075, copper, magnesium, and Al2024. Cold gas spraying was
chosen because it is an effective method for depositing coatings without excessive heating, thus preserving
the structural properties of both the coating and the substrate. In optimizing the spray parameters, the best
conditions for coating titanium on the Al7075 alloy were identified: a spraying pressure of 40 bar, a gas
temperature of 800°C, a gun traverse speed of 4 m/s, and a distance of 50 mm between the spray gun and
the sample.
After the coatings were applied to the different substrates, several mechanical tests were conducted, focusing
on hardness, elasticity modulus, and workability. A total of 36 nano-hardness and elasticity tests were
performed on each substrate, allowing for the calculation of average values for each property. These results
were summarized in a table, and a graph was plotted to illustrate the relationship between workability and
elasticity. Interestingly, the experimental data points did not show a clear correlation between these two
properties, indicating that the behavior of materials in terms of elasticity and workability may not be directly
linked or may be influenced by other factors.
In addition to the mechanical property measurements, adhesion tests were conducted to determine how
strongly the titanium coatings adhered to each substrate. The results did not show a strong correlation between
adhesion strength and either workability or elasticity, suggesting that the adhesion process is likely governed
by more complex factors beyond just the mechanical properties of the substrate. These discrepancies may be
due to the intricate nature of the adhesion mechanisms or limitations in measurement accuracy, which could
obscure any potential trends or relationships.
