**3. Results and discussion**

#### **3.1 Strength of adhesion**

The adhesion strength of the cold-sprayed TiO2 coating on annealed Al 1050 pure aluminum are shown in **Figure 1**. The TiO2 coating on the annealed soft

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**Figure 2.**

**Figure 1.**

*Influence of Annealed Aluminum Properties on Adhesion Bonding of Cold Sprayed Titanium…*

substrates showed a decreased trend of adhesion strength from room temperature to 400°C, with values from 3.88 to 2.05 MPa. The increase of annealed substrate

**3.2 SEM cross-section microstructure of TiO2 coatings on annealed Al 1050** 

**Figure 2a**–**e** shows the TiO2 coating cross-sectional area on Al 1050 for various substrate annealing temperatures. Under all condition figures, the figures show a dense coating with a thickness in the range of 200 to 300 μm, indicating that a critical velocity was reached for this soft material. This suggests that the TiO2 coating adhered well to the annealed Al 1050 substrate from room temperature to

We can categorize the cold-spraying procedure into two stages: (1) adhesion and (2) cohesion bonding. Adhesion or the formation of the interface between the substrate and particle is the first stage. The annealed substrates can clearly implement this stage, which forms the first coating layer, particularly for the soft material,

**Figure 3** shows the annealing substrate hardness of Al 1050 from room temperature to 400°C. The pure aluminum, Al 1050 showed a decreasing trend from

*Cross-section microstructure of TiO2 coatings on Al 1050. (a) Room temperature; (b) annealed 100°C;* 

45.36Hv for room temperature to 27.70Hv for 400°C annealing.

temperature also showed a thicker surface oxide on substrate surface.

*DOI: http://dx.doi.org/10.5772/intechopen.94097*

**3.3 Substrate Vickers microhardness**

*Adhesion strength of the TiO2 coating on annealed Al 1050.*

*(c) annealed 200°C; (d) annealed 300°C and (e) annealed 400°C.*

**substrates**

400°C annealing.

Al 1050.

*Influence of Annealed Aluminum Properties on Adhesion Bonding of Cold Sprayed Titanium… DOI: http://dx.doi.org/10.5772/intechopen.94097*

substrates showed a decreased trend of adhesion strength from room temperature to 400°C, with values from 3.88 to 2.05 MPa. The increase of annealed substrate temperature also showed a thicker surface oxide on substrate surface.
