Pingdi Ren

Fretting wear behavior of Inconel 690 in hydrazine environments

The friction and wear behaviors of Inconel 690 flat against Si3Ni4 ball were investigated using a hydraulic fretting test rig equipped with a liquid container device. The loads of 20–80 N, reciprocating amplitudes of 80–200 μm and two different environments (distilled water and hydrazine solution at temperatures from 25 to 90 °C) were selected. The results show that the ratio of Ft/Fn is lower in distilled water than that in hydrazine solution at the same temperature in the slip regime. Both the ratio of Ft/Fn and wear volume gradually increase with increasing medium temperature under the given normal load and displacement amplitude. Besides the displacement amplitude and load, temperature also plays an important role for wear behavior of Inconel 690 material. The increase of temperature could reduce the concentration of dissolved oxygen, and promote the absorption reaction of hydrazine and dissolved oxygen. As a result, the oxidative corrosion rate is obviously lowered. Abrasive wear and delamination wear are the main mechanisms of Inconel 690 in distilled water. However, in hydrazine solution the cracks accompanied by abrasive wear and delamination wear are the main mechanisms.

Fretting wear and friction oxidation behavior of 0Cr20Ni32AlTi alloy at high temperature

The fretting wear behavior of 0Cr20Ni32AlTi alloy was investigated with crossed cylinder contact under 80 N at 300 and 400 °C. Wear scar and debris were analyzed systematically by scanning electron microscopy and X-ray photoelectron spectroscopy. The results show that the friction logs are mixed fretting regime and gross slip regime with the magnitudes of displacement of 10 and 20 μm, respectively. Severe wear and friction oxidation occur on the material surface. A large number of granular debris produced in the fretting process can be easily congregated and adhered at the contact zone after repeated crushes. The resultant of friction oxidation is mainly composed of Fe3O4, Fe2O3, Cr2O3 and NiO. Temperature and friction are the major factors affecting the oxidation reaction rate. The fretting friction effect can enhance the oxidation reaction activity of surface atoms of 0Cr20Ni32AlTi alloy and reduce the oxidation activation energy. As result, the oxidation reaction rate is accelerated.

Experimental Study of the Fretting Wear Behavior of Incoloy 800 Alloy at High Temperature

ABSTRACT The fretting wear behavior of the nuclear power material Incoloy 800 was investigated in this study. A PLINT high-temperature fretting tester was used on an Incoloy 800 cylinder against a 304SS cylinder at vertical cross contact under different temperatures (25, 300, and 400°C). During testing, a normal load of 80 N was applied, and the displacement amplitudes ranged from 2 to 40 µm. The fretting wear mechanism at high temperatures and the kinetic character of the materials of the Incoloy 800 steam generator tube were analyzed. Results showed that the fretting running regimes varied little with ncreasing temperature, and some microcracks were observed in both the mixed fretting regime (MFR) and the partial slip regime (PSR) at high temperatures. Slight abrasive wear and microcracks were the main wear mechanisms of the Incoloy 800 alloy in PSR, whereas those in the MFR and the gross slip regime were oxidative wear, abrasive wear, and delamination.

Experimental study of the fretting wear behavior of Inconel 690 alloy under alternating load conditions

This study investigated the fretting wear behavior of the nuclear power material Inconel 690 alloy. An improved PLINT high-temperature fretting tester was used on an Inconel 690 tube against a 1Cr13 cylinder at different temperatures (25 ℃ and 300 ℃) under alternating load conditions. The fretting-wear mechanism and the kinetic characteristic of Inconel 690 alloy were analyzed. Results showed that the fretting running behavior was closely related to the normal excitation frequency. In parallelogram shaped Ft–D curves, the friction fluctuates periodically, and accordingly the fretting was running in the slip regime. The steady-state friction force at room temperature in air was higher than that at 300 ℃. Moreover, the damage behavior of the fretting for Inconel 690 alloy strongly depended on the normal load, displacement amplitude, temperature, and excitation frequency in atmospheric environment. A superposition effect of fretting wear behavior was discovered because of the combined effect of alternating normal and tangential forces; thus, delamination became more significant. Abrasive wear and delamination were the major mechanisms in Inconel 690 alloy at room temperature in ambient air. The dominant mechanisms at 300 ℃ were the abrasive wear, oxidation wear, and delamination.