Unlubricated Sliding Wear of Nickel Aluminides at Room Temperature and 400°C

Abstract

Unlubricated sliding tests were performed at room temperature and at 400°C on polycrystalline Ni3Al with and without boron and on IC218, an alloy containing nickel plus 8.94 Al, 7.55 Cr, 0.88 Zr, 0.015 B and 0.01 Hf (all in wt. %). A pjn/disk geometry was used with self-mated samples in air and vacuum (1.3×10-3 Pa). Normal load was 1.5 kg (14.7 N), sliding speeds were 15–19 mm/s and sliding distances were 145–175 m.It had been expected that materials with and without boron would behave differently during sliding because of their well-known differences in ductility and fracture resistance. However, sliding behavior was similar for materials with and without boron. Environmental effects were more dramatic. For tests in vacuum, the friction trace was very noisy and the average coefficient of friction varied erratically during most of each test. Wear debris ranged from 100 μm to 1 mm in size. Wear scars were smooth, but with signs of heavy deformation. All test materials exhibited smoother sliding behavior in air than in vacuum, but the wear rate was usually higher in air. Debris particles were finer, most of them were at least partially oxidized, and they included at least one ferromagnetic component, probably arising from selective oxidation. It is suggested that the increased wear rate in air is related to oxygen-enhanced fracture of these nickel aluminides.

Rational Design and Synthesis of Efficient Sunscreens To Boost the Solar Protection Factor

“…On the contrary, the positive charge causes stronger,r ed-shifted absorption bands.A saconclusion, 6, 7, and 8 are the most promising cores.However, 7 is known [31,32] to be chemically unstable due to the Hinposition 2. In addition, afast decay to the ground state was demonstrated for 6 and 8 by NAMD (Supporting Information), with an averaged S 1 life-time of 239 AE 65 fs (8), on the same order as the natural sunscreen eumelanin, [27] but much faster than commercial sunscreens components (6 ps for avobenzone in S 1 [28] and 665 ns in T 1 , [29] 600 fs and 2-3 ps for oxybenzone [30] ).…”

Study on Wear Behaviors of Ni₃Al/Cr-Carbides Cladding Layer on High Strength Steel Substrate

“…The powder sizes of NAC-alloy and Cr3C2 particles applied for HIP processed are in a range of 45µm-120µm, respectively. The density of NAC-alloy and Cr3C2 particles used for calculating volume composition of the composites are 7.25 g/cm 3 and 6.68 g/cm 3 , respectively. The HIP process data are 1130 -1160 °C as heating temperature under 140 MPa for 3 hours.…”

“…Ni3Al-based alloys exhibit increased yield strength with increase of temperature to about 650-750 ºC, which made them an attractive engineering materials with good wear resistance. Due to these properties, Ni3Al-based alloys have significant potential in wear critical applications at temperature range between 400 ºC and 650 ºC [1][2][3][4][5][6] . Intermetallic matrix composites (IMC) with hard particles reinforcements are considered for wear applications in severe, i.e.…”

The effects of environment on the dry sliding wear of eutectic Fe30Ni20Mn35Al15

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