- 上一篇：室内环境和反射涂层对建筑能耗影响英文文献和翻译
- 下一篇：铝合金汽车活塞制造英文文献和中文翻译
energy dispersive x-ray spectroscopy (EDX). X-ray photo-
electron spectroscopy (XPS) using a 5600 Multi-Technique
System (PHI, USA) was applied to study the elemental
distribution and oxidation status of elements in the coatings.
The sample surfaces were analyzed, and then the interior
after 6-min sputtering with a 4 kV Ar
? gun (5 9 5 raster
and 23.5 A/min sputter rate on SiO2/Si reference samples).
The crystalline structure was studied using XRD with CuKa
radiation (wavelength k = 0.1541 nm) using a Scintag h:h
powder diffractometer, equipped with a liquid nitrogen
cooled Ge solid-state detector. The scanning range was
between 2h = 20 and 70.
The coating’s hardness was measured using a microh-
ardness tester equipped with a Knoop indenter at a load of
0.1 N. Every microhardness (HK) value was the average of
five measurements. The coating adhesion was assessed by a
scratch test (CSM-REVETEST) using a diamond indenter
whose radius of curvature was 0.2 mm. Each scratch was
5 mm long at constant load, after which the scratch track
was examined by optical microscopy. The scratch load was
increased until the first appearance of coatings failure
(defined as substrate exposure), determining a critical load,
Lc. The tribological behavior was studied using a tribom-
eter (CSM) against a 300
WC ball in ambient air. The linear
sliding speed was 0.1 m/s. Two sets of tests were con-
ducted: (1) with a load of 1 N and a sliding distance of
300 m, and (2) a load of 5 N and a sliding distance of
100 m. After the wear test, the cross section of the wear
track was measured using a profilometer and was used to
calculate the wear coefficient, W = V/Ls where V is theremoved volume, L is the load, and s is the sliding distance
[32].
Results
Arc behavior and ion current measurements
Influence of the arc current on cathode spot motion and ion
current
The saturated ion current, Ip, was measured as a function of
Iarc using the straight duct configuration (Fig. 1b). For Zr
arcs, increasing Iarc from 50 to 100 A increased Ip from 1.4
to 2.5 A. However, with further increases of Iarc, Ip
decreased sharply, to 0.3 A at Iarc = 175 A. Visual obser-
vation of the cathode spot motion showed that initially
increasing Iarc increased the number of cathode spots on the
cathode front face. However, when Iarc C 100 A, the
number of spots on the face decreased as they concentrated
on the peripheral conical surface. At Iarc C 150 A, no spots
were observed on the cathode front face. The same quali-
tative behavior was found for the Al cathode. The highest
Ip = 1.9 A, and the most intense spot activity on Al cathode
front surface were observed at Iarc = 75 A.
Influence of oxygen pressure on the arc behavior
Figure 2 shows the influence of P on Ip collected from Zr
and Al cathodes, in the straight duct configuration. The
open symbols represent an oxygen environment (PO2
) and
the solid symbols, a mixed Ar ? O2 environment (PAr=O2
).
In vacuum, Al and Zr had an Ip of 1.9 and 2.5 A, respec-
tively. Introduction of O2 sharply decreased (Ip)
Al
to 0.9 A
at PO2
= 0.2 Pa, and then it was maintained almost con-
stant up to PO2
= 0.5 Pa. Further increase in PO2
rapidly
decreased (Ip)
Al
to 0.1 A at PO2
= 1 Pa. For Zr, a similar
trend was found, although (Ip)
Zr
decreased constantly, with
a lower decrease rate in the pressure range 0.2\PO2
\
0.5 Pa. The experiments in oxygen environment were
characterized by unstable arc operation and a tendency for
the arc to spontaneously extinguish.
Addition of Ar to the environment increased Ip consid-