# Copper Alloys Performance in High-Pressure and Low-Velocity Conditions Using a Custom Tribometer  
[PERSON]  
1 Surface Phenomena Laboratory, Escola Politecnica da Universidade de Sao Paulo,  
Sao Paulo 05508-010, Brazil; [EMAIL_ADDRESS]  
2 Centro de Pesquisa, Desenvolvimento e Brasios da Termecanica Sao Paulo S.A.,  
Sao Paulo 09612-000, Brazil; [EMAIL_ADDRESS] (V.T.d.S);  
[EMAIL_ADDRESS] (F.G.L. ); [EMAIL_ADDRESS] (D.A.S.) 2 Centro de Pesquisa, Desenvolvimento e Brasios da Termecanica Sao Paulo S.A.,  
Sao Paulo 09612-000, Brazil; [EMAIL_ADDRESS] (V.T.d.S);  
[EMAIL_ADDRESS] (F.G.L. ); [PERSON]S] (D.A.S.) 2 Centro de Pesquisa, Desenvolvimento e Brasios da Termecanica Sao Paulo S.A.,  
Sao Paulo 09612-000, Brazil; [EMAIL_ADDRESS] (V.T.d.S);  
[EMAIL_ADDRESS] (F.G.L. ); [EMAIL_ADDRESS] (D.A.S.) 2 Centro de Pesquisa, Desenvolvimento e Brasios da Termecanica Sao Paulo S.A.,  
Sao Paulo 09612-000, Brazil; [EMAIL_ADDRESS] (V.T.d.S);  
[EMAIL_ADDRESS] (F.G.L. ); [PERSON]S] (D.A.S.) 2 Centro de Pesquisa, Desenvolvimento e Brasios da Termecanica Sao Paulo S.A.,  
Sao Paulo 09612-000, Brazil; [EMAIL_ADDRESS] (V.T.d.S);  
[EMAIL_ADDRESS] (F.G.L. ); [PERSON]S] (D.A.S.) 2 Centro de Pesquisa, Desenvolvimento e Brasios da Termecanica Sao Paulo S.A.,  
Sao Paulo 09612-000, Brazil; [EMAIL_ADDRESS] (V.T.d.S);  
[EMAIL_ADDRESS] (F.G.L. ); [EMAIL_ADDRESS] (D.A.S.) 2 Centro de Pesquisa, Desenvolvimento e Brasios da Termecanica Sao Paulo S.A.,  
Sao Paulo 09612-000, Brazil; [EMAIL_ADDRESS] (V.T.d.S);
increase (\(\Delta\)T), the thermal conductivity of sliding bearing material (\(\rm{k_{T}}\)), and the thickness of the bearing base material (s) [1, 6]. \[P.V=\frac{k_{T}}{\mu.s}.\Delta T \tag{2}\]  
When evaluating (2), it is essential to consider situations with high pressures and/or velocities, i.e., higher PV factors. These situations require bearing materials with high thermal conductivity, low friction coefficients, and the ability to withstand high surface temperatures. This gradually brings greater importance to the correct selection of journal-bearing material. In this context, copper alloys have been historically extensively used in bearing bushings since the first steam engines, mainly due to the high thermal conductivity associated with low friction coefficient values when in contact with ferrous alloys. In the present context, it is worth emphasizing two significant types of alloys: high-lead tin bronzes and nickel aluminum bronzes [2, 6, 7, 8]. High-lead tin bronze alloys, containing up to 30% lead by weight, stand out as one of the most suitable alloys for the intended purpose. The insolubility of lead in the CuSn matrix gives rise to a microstructure consisting of successive copper-rich matrices interspersed with low-shear strength lead \"sponges\", being the main reason to employ alloys with the most significant lead content possible, resulting in a self-lubrication mechanism triggered by the extrusion of lead inclusions [7, 8, 9, 10, 11, 12, 13]. Copper-aluminum-nickel-iron (CuAlNiFe) alloys, known as nickel aluminum bronze (NAB), contain around 5% wt. nickel and iron, which causes the intentional formation of \(\kappa\) (kappa) phases. Although they do not have self-lubricating properties, these alloys are a popular choice for journal bearings that operate in harsh environments, as they offer higher strength, wear, and corrosion resistance and can withstand elevated temperatures that often exceed 260 \({}^{\circ}\)C. However, while these alloys have excellent mechanical resistance, they tend to have lower ductility and require specific care regarding surface finishing, assembly alignment, and lubricating oil cleaning [2, 8, 14, 15, 16, 17, 18, 19, 20]. Tribology studies are fundamental to accessing enhanced performance and new copper alloys and composites in journal bearings applications. There are several ways to establish a good tribological study through theoretical approaches and computational simulations, but experimental analysis remains decisively essential.