**4.1 Materials and experimental procedure**

## *4.1.1 Materials*

The developed lead-free material is based on bronze-type Cu-Sn alloy and contains sulfide. For friction materials that use a sintering process, sulfides are considered to be an alternative element to lead, tested as TP-L (Cu-10 Sn-10 Pb mass%: lead bronze) and TP-A1 (Cu-12.15 Sn-1.78 Fe-0.48 S mass%) and for the purpose of comparing tribological properties using new materials prepared as TP-B1 (Cu-11.93 Sn-1.44 Fe-1.78 S mass%). The test specimen is sintered and rolled onto a steel plate, and the powder is separated. This plate was heated in furnace under reduction condition. In order to sinter to make the bimetal, the powder on the plate has to be heated at 1113 K for 10 min. After sintering, reduce the thickness of the plate by rolling, then sinter the rolled bimetallic, and roll again under the same conditions used in the initial.

#### *4.1.2 Friction test*

The friction test was performed using a ring on disk tester. The contact load was applied by its own weight and was in the range of 50–600 N. Disk specimens were attached to a shaft driven by a DC motor. The sliding speed could be controlled continuously in the range of 0.1–1.4 m/s. Mineral oil (approximately 30 μL, three drops from a microsyringe) is delivered to the interface just prior to testing. The disk surface was first contacted with the ring, and then the disk specimen was driven.

**153**

**Figure 14.**

*Results of friction test [11].*

*Effects of Dispersed Sulfides in Bronze During Sintering DOI: http://dx.doi.org/10.5772/intechopen.86385*

(carbon steel).

low load [12].

friction.

**4.2 Results and discussion**

The laboratory air and the laboratory environment under the break-in process had a load of 20 N and were applied at a sliding distance of 120 m before testing. These specimens and carbon steel disks (S45C) were mirror finished. The roughness was Ra 0.025 μm (TP-L), Ra 0.167 μm (TP-A), Ra 0.343 μm (TP-B), and Ra 0.004 μm

After interrupting at 20 N for 10 min in operating mode (friction distance 120 m), gradually load the ring in 50 N increments until a friction coefficient of 0.2 is reached or strange noise occurs. In the lubricant test, PAO (50 cSt @ 313 K) was used as a lubricant. Another test was performed on this material for high speed and

Friction coefficient during the test was shown in **Figure 14**. In the beginning of

Friction coefficient of TP-L also shows a low coefficient of friction at the beginning of the test. After that, the friction coefficient abruptly increases at a load of 300 N. The friction coefficient between TP-A and TP-B is reduced at 200 and 300 N load. From the result, these sintered specimens could achieve a lower coefficient of

Lubricating oil seems to hinder the formation of S-based coatings. Due to the pores passing through the lubricating oil, the difference in coefficient of friction is

From **Figure 15a–d**, surface state after the test was observed. Attachment to the ring (carbon steel/S45C) of the copper alloy particles (TP-B) which is a part of the disk is observed (see the circle in **Figure 15b**). On the other hand, adhesion of the part of carbon steel to the disk was observed as shown in **Figure 15c**. The adhesion of the Cu alloy to carbon steel achieves a lower coefficient of friction than the adhesion of carbon steel to Cu alloy at high loads. These phenomena also reported another kind of friction test as sulfides play a role as solid lubricants [13].

the test, lower friction coefficient of around 0.05 was measured in TP-B.

not so wide between the dry test and the lubricating oil test.

#### *Effects of Dispersed Sulfides in Bronze During Sintering DOI: http://dx.doi.org/10.5772/intechopen.86385*

The laboratory air and the laboratory environment under the break-in process had a load of 20 N and were applied at a sliding distance of 120 m before testing. These specimens and carbon steel disks (S45C) were mirror finished. The roughness was Ra 0.025 μm (TP-L), Ra 0.167 μm (TP-A), Ra 0.343 μm (TP-B), and Ra 0.004 μm (carbon steel).

After interrupting at 20 N for 10 min in operating mode (friction distance 120 m), gradually load the ring in 50 N increments until a friction coefficient of 0.2 is reached or strange noise occurs. In the lubricant test, PAO (50 cSt @ 313 K) was used as a lubricant. Another test was performed on this material for high speed and low load [12].

#### **4.2 Results and discussion**

*Design and Manufacturing*

**3.4 Summary**

no correlation.

*4.1.1 Materials*

used in the initial.

*4.1.2 Friction test*

ing under the same sintering temperature.

**4. Friction properties of sulfide bronze**

caused improved tribological properties [11].

**4.1 Materials and experimental procedure**

Moreover, some specimens only sintering under inert atmosphere shown in **Figure 13b** were not harder than specimens only sintering under reduced atmosphere shown in **Figure 13a**, relatively. Reducing atmosphere might progress sinter-

From these results, by using pre-alloyed atomizing bronze-containing sulfides,

The effect of sulfur or sulfide on the mechanical properties of bronze specimens sintered under reducing inert gas atmosphere was investigated by subjecting water-atomized sulfide-dispersed bronze specimens to sintering. Furthermore, solid-phase sintering and liquid sintering were compared for the same Sn content. By using pre-alloyed atomizing bronze-containing sulfides, no mechanical properties were observed that decreased significantly as hardness. The sulfide content of the specimens decreased during sintering in a reducing atmosphere. With regard to mechanical properties such as hardness, the Sn content affected the properties regardless of whether the specimen had undergone solid-phase sintering or liquid sintering. In contrast, the sulfur and sulfide content and mechanical properties had

In this study, tribological properties of copper alloys with sulfide particles are discussed. Friction characteristics were measured under dry and lubricated conditions to evaluate the effect of sulfide particles. Graphite penetrating into the pores

The developed lead-free material is based on bronze-type Cu-Sn alloy and contains sulfide. For friction materials that use a sintering process, sulfides are considered to be an alternative element to lead, tested as TP-L (Cu-10 Sn-10 Pb mass%: lead bronze) and TP-A1 (Cu-12.15 Sn-1.78 Fe-0.48 S mass%) and for the purpose of comparing tribological properties using new materials prepared as TP-B1 (Cu-11.93 Sn-1.44 Fe-1.78 S mass%). The test specimen is sintered and rolled onto a steel plate, and the powder is separated. This plate was heated in furnace under reduction condition. In order to sinter to make the bimetal, the powder on the plate has to be heated at 1113 K for 10 min. After sintering, reduce the thickness of the plate by rolling, then sinter the rolled bimetallic, and roll again under the same conditions

The friction test was performed using a ring on disk tester. The contact load was applied by its own weight and was in the range of 50–600 N. Disk specimens were attached to a shaft driven by a DC motor. The sliding speed could be controlled continuously in the range of 0.1–1.4 m/s. Mineral oil (approximately 30 μL, three drops from a microsyringe) is delivered to the interface just prior to testing. The disk surface was first contacted with the ring, and then the disk specimen was driven.

decreasing mechanical properties as hardness were not observed.

**152**

Friction coefficient during the test was shown in **Figure 14**. In the beginning of the test, lower friction coefficient of around 0.05 was measured in TP-B.

Friction coefficient of TP-L also shows a low coefficient of friction at the beginning of the test. After that, the friction coefficient abruptly increases at a load of 300 N. The friction coefficient between TP-A and TP-B is reduced at 200 and 300 N load. From the result, these sintered specimens could achieve a lower coefficient of friction.

Lubricating oil seems to hinder the formation of S-based coatings. Due to the pores passing through the lubricating oil, the difference in coefficient of friction is not so wide between the dry test and the lubricating oil test.

From **Figure 15a–d**, surface state after the test was observed. Attachment to the ring (carbon steel/S45C) of the copper alloy particles (TP-B) which is a part of the disk is observed (see the circle in **Figure 15b**). On the other hand, adhesion of the part of carbon steel to the disk was observed as shown in **Figure 15c**. The adhesion of the Cu alloy to carbon steel achieves a lower coefficient of friction than the adhesion of carbon steel to Cu alloy at high loads. These phenomena also reported another kind of friction test as sulfides play a role as solid lubricants [13].

**Figure 14.** *Results of friction test [11].*

**Figure 15.** *Surface of disks and rings after the test [11].*

In particular, MoS2 was a common solid lubricant. Mixed MoS2 in the Cu-based sintered material had better friction characteristics [14]. The sliding mechanism of MoS2 is well known, and it is possible that a born person has the same or similar sliding mechanism as MoS2 [15–17].

### **4.3 Summary**

A friction test was conducted on the developed sintered Cu alloy-containing sulfide particles. The friction performance of the developed material was compared with those containing lead. The following is a summary of the results obtained.

The change in coefficient of friction depends on the behavior of the adhesive layer, especially under high load.

Sulfide-dispersed porous sintered Cu alloy realizes stabilization of friction coefficient at higher load than lead bronze.
