**3.7. Effect of bamboo fiber on friction performance**

It can be found from **Figure 11** that the friction coefficients of BFRFMs with 3, 6, and 9 wt.% bamboo fibers were higher than those of the friction materials without bamboo fibers. The friction coefficients of the BFRFMs have significant variations at the test temperature of 250°C. This is because phenolic resin began to pyrolyse, and the bamboo fibers were carbonized gradually when temperature exceeded 250°C. However, the friction coefficient of BFRFMs containing 12 wt.% bamboo fibers decreased with the increase of test temperature.

It can be seen from **Figure 12** that wear rates of the BFRFMs generally increased with the increase of test temperature since the matrix began to soften, and the bamboo fibers were carbonized with the increase of test temperature. The surface roughness of friction materials containing 6, 9, and 12 wt.% bamboo fibers was high, so the adhesive wear and microcutting wear appeared on the worn surface. This is because the heat fading of the phenolic resin appeared, and the small hard particles formed from some glass fibers separated from the matrix. Plenty of wear debris formed and fell off, so the wear rate of friction materials significantly increased. The wear rate of friction materials containing 3 wt.% bamboo fibers was the lowest. In fact, some voids and grooves formed after the carbonization of the bamboo fibers can contain some other abrasive particles.

#### **3.8. Wear surface morphologies of BFRFMs**

**Figure 10.** Bamboo fiber assemblies.

bamboo fiber.

98 Bamboo - Current and Future Prospects

**Figure 8.** Test result of tensile stress-strain curve of a bamboo fiber treated with alkaline solution.

**Figure 9.** Morphologies of tensile fracture of (a) the bamboo fiber treated with alkaline solution; and (b) the untreated

The worn surface morphologies of the BFRFMs are shown in **Figure 13**. It can be seen from **Figure 13** that some glass fibers exposed and some did not separate from the matrix. The glass fibers and friction surfaces were supported by the matrix. Some hard particles from the glass

**Figure 11.** Variation of the friction coefficient of the bamboo fiber reinforced friction materials with the temperature.

fiber formed under the friction force and the glass fibers did not separate from the matrix completely. It illustrated that the glass fibers were firmly bound with the matrix. Graphite and some particles that carbonized existed on the friction surface, so part of the friction surface was very smooth and easily deformed under friction force and shear force. Therefore, wear resistant surface was formed, and the friction coefficient and wear rate were decreased. Meanwhile, the carbonized fiber can repair the scratch and shallow pits on the worn surface, so the adhesive wear was decreased to some extent [30, 31], and the worn surface is relatively smooth. The grooves or voids (**Figure 14**) formed after the carbonization of the fibers reduced

**Figure 14.** Morphologies of the groove and voids of the BFRFMs with bamboo fibers of (a) 3 wt.%; and (b) 6 wt.%.

**a.** Dry sliding wear of bamboo (*P. pubescens*) stem is dependent upon the normal load, the sliding velocity, and the cellulose fiber (vascular bundle), and orientation with respect to the rubbing surface. The wear volume of bamboo increases with the crease of the normal load and sliding velocity. Normal-oriented specimens exhibit better wear resistance than paralleloriented ones, and the outside surface layer has better wear resistance than the inner layer. **b.** Material transfer phenomena from bamboo to the counterface occur for three types of bamboo specimens. The predominant wear mechanisms are adhesion, microcracking, and microploughing under low load at low velocity, and microploughing-microcutting under


adhesion, and particularly microcracking and microploughing-microcutting. The wear of N-type specimens is mainly due to adhesion and microcracking, and the matrix tissue

**c.** The friction coefficients of friction materials containing 3, 6, and 9 wt.% bamboo fibers increased with increase of the test temperature, whereas the friction materials containing


Bamboo Wear and Its Application in Friction Material http://dx.doi.org/10.5772/intechopen.69893 101

the noise and adhere to wear debris on the wear surface of friction materials [32].

**4. Conclusion**

high load for PS

shows certain wear resistance.

12 wt.% bamboo fibers decreased.

**Figure 12.** Variation of wear rate of the bamboo fiber reinforced friction materials with temperature.

**Figure 13.** Surface morphologies of the BFRFMs with bamboo fibers of (a) 3 wt.%; (b) 6 wt.%; (c) 9 wt.%; and (d) 12 wt.%.

**Figure 14.** Morphologies of the groove and voids of the BFRFMs with bamboo fibers of (a) 3 wt.%; and (b) 6 wt.%.

fiber formed under the friction force and the glass fibers did not separate from the matrix completely. It illustrated that the glass fibers were firmly bound with the matrix. Graphite and some particles that carbonized existed on the friction surface, so part of the friction surface was very smooth and easily deformed under friction force and shear force. Therefore, wear resistant surface was formed, and the friction coefficient and wear rate were decreased. Meanwhile, the carbonized fiber can repair the scratch and shallow pits on the worn surface, so the adhesive wear was decreased to some extent [30, 31], and the worn surface is relatively smooth. The grooves or voids (**Figure 14**) formed after the carbonization of the fibers reduced the noise and adhere to wear debris on the wear surface of friction materials [32].
