Wyniki wyszukiwania - BazTech

1

Tribological Characteristic of Titanium Alloy Surface Layers Produced by Diode Laser Gas Nitriding

Lisiecki A., Piwnik J.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 2A

543--552

EN

In order to improve the tribological properties of titanium alloy Ti6Al4V composite surface layers Ti/TiN were produced during laser surface gas nitriding by means of a novel high power direct diode laser with unique characteristics of the laser beam and a rectangular beam spot. Microstructure, surface topography and microhardness distribution across the surface layers were analyzed. Ball-on-disk tests were performed to evaluate and compare the wear and friction characteristics of surface layers nitrided at different process parameters, base metal of titanium alloy Ti6Al4V and also the commercially pure titanium. Results showed that under dry sliding condition the commercially pure titanium samples have the highest coefficient of friction about 0.45, compared to 0.36 of titanium alloy Ti6Al4V and 0.1-0.13 in a case of the laser gas nitrided surface layers. The volume loss of Ti6Al4V samples under such conditions is twice lower than in a case of pure titanium. On the other hand the composite surface layer characterized by the highest wear resistance showed almost 21 times lower volume loss during the ball-on-disk test, compared to Ti6Al4V samples.

2

Comparison of Titanium Metal Matrix Composite Surface Layers Produced During Laser Gas Nitriding of Ti6Al4V Alloy by Different Types of Lasers

Lisiecki A.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 4

1777--1784

EN

The article presents the results of a comparative study of the nitriding process of titanium alloy substrate using two lasers with different characteristics of laser beams. One of the applied lasers was a high power diode laser emitting at a dominant wavelength of 808 nm, with a rectangular laser beam spot, and multimode energy distribution across the spot. The second laser was a solid state Yb:YAG disk laser emitting at a wavelength of 1.03 μm, with a circular beam spot, characterized by near Gaussian energy distribution across the spot. In a case of both lasers single stringer beads with a similar width and at similar energy input were produced. As a result of melting of the substrate with a laser beam in a pure gaseous nitrogen atmosphere composite surface layers with in situ precipitated titanium nitrides embedded in the metallic matrix of titanium alloy were produced, in both cases. However, the surface topography and structure is different for the surface layers produce by different lasers at the same processing parameters and width of laser beams.

3

Rolling contact fatigue of Ti64 bearings before and after laser gas nitriding

Santos E.C., Kida K., Rozwadowska J., Kashima Y.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2011

|

z. 99

50-52

EN

Due to their biocompatibility and high strength-to-weight ratio titanium and Ti alloys are widely used in high end application in the medical and aeronau- tical industries. The materials` low wear resistance presents a disadvantage that is approached in this work. In order to enhance the rolling contact fa- tigue properties of the bearings` working surface, a laser coating technique was used. Non-coated and coated specimens were tested in equal conditions and it was found that layers of titanium nitride significantly improve the rolling contact fatigue performance of titanium components.

4

Diode laser surface modification of Ti6Al4V alloy to improve erosion wear resistance

Lisiecki A., Klimpel A.

Archives of Materials Science and Engineering

|

2008

|

Vol. 32, nr 1

5-12

EN

Purpose: Purpose of this paper : The purpose of the study was to develop new laser alloying technology providing high erosion wear resistance of the working surfaces of blades made of titanium alloy Ti6Al4V. Design/methodology/approach: High power diode laser HPDL with a rectangular laser beam spot of multimode and uniform intensity of laser radiation was applied in the process of laser surface modification of the titanium alloy Ti6Al4V. During the laser surface remelting and alloying of the titanium alloy in argon and nitrogen atmospheres, surface layers of high hardness and significantly higher erosion wear resistant, compared with the base material of titanium alloy Ti6Al4V, were produced. Findings: The surface layers are composites of titanium nitrides participations in the titanium alloy matrix. Hardness of the surface layers and erosion wear resistance depends strongly on parameters of laser processing and on the partial pressure of nitrogen in the gas mixture of nitrogen-argon atmosphere. Research limitations/implications: The most critical parameter of the functional quality of titanium alloy blades of turbofan engine and steam turbines is the fatigue strength, therefore further investigations are required to determine the fatigue strength and also internal stresses in the nitrided surface layers. Practical implications: The novel technology of high power diode laser surface modification of the titanium alloy Ti6Al4V can be applied to produce erosion wear resistant and long lifetime surface layers of turbofan engine blades and steam turbine blades. Originality/value: The laser surface modification of titanium alloy by the high power diode laser with the rectangular laser beam spot of multimode and uniform intensity of laser radiation is very profitable in a case of laser surface remelting and alloying because the treated surface is heated uniformly, so uniform penetration depth and uniform thickness of the surface layer can be achieved, as opposed from circular laser beams of solid states YAG and gas lasers.

5

Diode laser gas nitriding of Ti6Al4V alloy

Lisiecki A., Klimpel A.

Archives of Materials Science and Engineering

|

2008

|

Vol. 31, nr 1

53-56

EN

Purpose: To produce erosion wear resistant and high hardness surface layers of turbofan engine blades and steam turbine blades made of titanium alloy Ti6Al4V laser gas nitrating (LGN) technology of laser alloying was selected to produce titanium nitrides participations in the titanium alloy matrix surface layers. Design/methodology/approach: Studies on influence of the parameters of laser gas nitriding of titanium alloy and partial pressure of nitrogen and argon in the gas mixture on the surface layers shape, penetration depth, microhardness, erosion wear resistance at different angles of erodent particles stream were conducted. The high power diode laser HPDL with a rectangular laser beam of even multimode intensity on the beam spot was applied in the laser gas nitriding process. Tests of erosion wear resistance were conducted according to the ASTM 76 standard at velocity of the erodent particles stream 70 [m/s], at angles 90 [°] and also 30 [°]. Findings: High quality surface layers of high hardness and erosion wear resistant were produced on the substrate of titanium alloy Ti6Al4V during Laser Gas Nitriding - LGN. Results of the study show that the erosion resistance of laser nitrided surface layers is significantly higher compared with the base material of titanium alloy Ti6Al4V, and depends strongly on the inclination angle of the erodent particles stream. Research limitations/implications: Further investigations of internal stresses in the nitrided surface layers and the fatigue strength of extremely hard surface layers are required, because the fatigue strength is decisive for the functional quality of the surface layers. Practical implications: The investigated technology of laser gas nitriding can be applied for increasing erosion wear resistance of surface layers of turbofan engine blades and steam turbine blades made of titanium alloy. Originality/value: Application of the rectangular diode laser beam spot of multimode and uniform intensity of laser radiation is very profitable in a case of laser surface remelting and alloying because it guarantees uniform heating of the treated surface, consequently uniform thermal cycle across the area of the beam interaction and also uniform penetration depth of the single bead of the surface layer.