**1. Introduction**

108 Tribology in Engineering

Vol. 43, pp. 591-600.

Vol. 123, pp. 305-312.

results, *Tribology International*, Vol. 39, pp. 839-845.

results. *ASME Journal of Tribology*, Vol. 130, 1-7.

journal bearing, *Tribology International*, Vol. 40, pp. 453-458.

for an offset half bearing. *Wear*; Vol. 117, No. 2, pp. 197–210.

*Transactions*, Vol. 38, No. 1, pp. 153-160.

*Transactions*, Vol. 38, No. 2, pp. 364-372.

303-310.

*Journal of Lubrication Technology*, pp. 777-792.

[14] Belforte, G.; Colombo, F.; Raparelli, T.; Trivella, A; Viktorov, V. (2008a). High speed electrospindle running on air bearings: design and experimental verification, *Meccanica*,

[15] Belforte, G.; Colombo, F.; Raparelli, T.; Viktorov, V.; Trivella, A. (2006). An experimental study of high speed rotor supported by air bearings: test rig and first experimental

[16] Della Pietra, L.; Adiletta, G. (2002). The squeeze film damper over four decades of investigations: part 1. Characteristics and operating features, *Shock Vib. Dig.*, vol. 34, pp. 3-26. [17] Belforte, G.; Colombo, F.; Raparelli, T.; Trivella, A., Viktorov, V. (2008b). High speed rotors with air bearings mounted on flexible supports: test bench and experimental

[18] Belforte, G.; Raparelli, T.; Viktorov, V. (1999). Theoretical investigation of fluid inertia effects and stability of self-acting gas journal bearings. *ASME Journal of Tribology*, Vol. 121, 836-843. [19] Belforte, G.; Raparelli, T.; Viktorov, V.; Trivella, A. (2007). Discharge coefficients of orifice-type restrictor for aerostatic bearings, *Tribology International*, Vol. 40, pp. 512-521. [20] Mishra, P. C.; Pandley R. K.; Athre K. (2007). Temperature profile of an elliptic bore

[21] Hashimoto, H. (1992). Dynamic characteristic analysis of short elliptical journal bearings in turbulent inertial flow regime, *STLE Tribology Transactions*, Vol. 35, No. 4, pp. 619-626. [22] Hashimoto, H.; Matsumoto K. (2001). Improvement of operating characteristics of high speed hydrodynamic journal bearings by optimum design: Part I – formulation of methodology and its application to elliptical bearing design, *ASME Journal of Tribology*,

[23] Wang N. Z.; Ho C. L.; Cha K. C. (2000). Engineering optimum design of fluid film lubricated bearings, *Journal of Tribology Transactions*, Vol. 43, No. 3, pp. 377-386. [24] Read, L.J.; Flack, R.D. (1987). Temperature, pressure and film thickness measurements

[25] Ene, N. M; Dimofte, F. & Keith Jr., T. G. (2008a). A dynamic analysis of hydrodynamic

[26] Ene, N. M; Dimofte, F. & Keith Jr., T. G. (2008b). A stability analysis for a hydrodynamic three-wave journal bearing, *Tribology International*, Vol. 41, No. 5, pp. 434-442. [27] Sehgal, R; Swamy, K.N.S.; Athre K.; Biswas S. (2000). A comparative study of the thermal behaviour of circular and non-circular journal bearings. *Lub Sci*, Vol. 12, No. 4, pp. 329–44. [28] Dimofte, F. (1995a). Wave journal bearing with compressible lubricant – Part I : The wave bearing concept and a comparison to the plain circular bearing, *Tribology* 

[29] Dimofte, F. (1995b). Wave journal bearing with compressible lubricant – Part II : A comparison of the wave bearing with a groove bearing and a lobe bearing, *Tribology* 

[30] Viktorov, V.; Belforte, G.; Raparelli, T., Colombo, F. (2009). Design of non-circular gas bearings for ultra-high speed spindle. *World Tribology Congress*, Kyoto, 6-11 Sept. C1-212. [31] Castelli, V.; Pirviks, J. (1968) Review of numerical methods in gas bearing film analysis.

[32] Colombo, F.; Raparelli, T.; Viktorov, V. (2009). Externally pressurized gas bearings: a comparison between two supply holes configurations. *Tribology International,* Vol. 42,

wave journal bearings, *STLE Tribology Transactions*, Vol. 51, No. 1, pp. 82-91.

There is an ongoing need for developing high temperature self-lubricating materials to meet the severe conditions of mechanical systems, such as advanced engines which require increasingly high working temperatures (at 1000 °C or above) and long life [1-7]. However, achieving and maintaining low friction and wear at high temperatures have been very difficult in the past and still are the toughest problems encountered in the field of tribology [8,9]. Yet, the efforts to explore novel high temperature self-lubricating materials possessing favorable frictional property and superior wear resistance abilities have never stopped. As a result, great strides have been made in recent years in the fabrication and diverse utilization of new high temperature self-lubricating materials that are capable of satisfying the multifunctional needs of more advanced mechanical systems [10-15]. The following tribological issues addressed in this chapter are presented:

