Page 133 - 摩擦学学报2025年第8期

第 8 期 左湘豫, 等: CO 2 对醇胺溶液摩擦学性能的影响与润滑机制研究 1231

metal surface and form a dense molecular brush structure, thereby prevented the direct contact of friction and reduced
friction. At the same time, the carboxylic acid base group in the CO 2 -absorbing alkylamine solution was more strongly
bound to the metal substrate than that in the unabsorbed CO 2 alkylamine solution, which made it easier for alkylamine to
undergo biochemical reactions under friction conditions and generate carbon-based friction film, further reducing
friction. Three alcohol amines were selected as absorption media, namely ethanolamine (MEA), 2-methyl-2-amino-1-
propanol (AMP), and 3-aminopropanol (3-AP). All were diluted to a weight concentration of 25% (water 60 g, alcohol
amine 20 g), and CO 2 was bubbled into them for 20, 40, and 60 min, respectively. Separately, the ethanolamine solutions
with absorption time of 0, 10, 20, 30, 40, 50 and 60 min were investigated by a four-ball friction tester (30 min, 98 N,
300 r/min) The friction coefficients of MEA, AMP, and 3-AP before absorbing CO 2 were 0.19, 0.20, and 0.29,
respectively. After absorbing CO 2 for 60 minutes, they were reduced to 0.13, 0.13, and 0.15, respectively. The friction
coefficients of MEA and AMP decreased by about 33% after absorbing CO 2 , while the friction coefficient of 3-AP
decreased by about 50%. But it was found that the diameter of the wear scars increased for all three alcohol amine
solutions after CO 2 absorption Because AMP exhibited the best anti-wear and friction reduction performance before and
after CO 2 absorption, AMP was selected as object for further study. Initially, at a constant load of 98N, the AMP
solution with CO 2 absorption for 40 minutes was compared with that without CO 2 absorption under rotational speed of
300, 600, 900 and 1 200 r/min. Subsequently, load conditions were varied to 98, 147, 196 and 245 N while maintaining a
constant speed of 300 r/min. Finally, two different AMP solutions underwent a one-hour friction experiment under a
load of 98 N and speed of 300 r/min. After the experiment, the friction coefficient decreased and the wear increased after
absorbing CO 2 . The worn surface was analyzed using non-contact three-dimensional surface profilers, scanning electron
microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) to examine
element distribution, elemental content and chemical states. It was observed that the wear scars generated from AMP
solutions without CO 2 absorption appeared relatively clean, whereas the wear scar from AMP solutions with CO 2
absorption for 40 min was surrounded by a significant number of black substances. In other words, the AMP solution
that had absorbed CO 2 for 40 min formed a carbon-based tribofilm after undergoing four-ball friction test. The EDS
scanning was utilized to analyze the elemental composition of the two wear scars. It was observed that, compared with
AMP solutions without CO 2 absorption, the carbon content of wear scar from AMP solutions with CO 2 absorption had
increased from 3.19% to 6.49%, nitrogen content had increased from 0.13% to 0.46%, and iron content had decreased
from 94.48% to 90.76%.
The oxygen content remained relatively unchanged. X-ray photoelectron spectroscopy (XPS) analysis revealed the
presence of C=O, C-C and C-O bonds in the C1s spectrum, with binding energy peaks at 288.9, 288.4, 285.3, 285.1 and
284.8 eV. The N1s spectrum had shown a binding energy peak at 399.7eV, indicated the existence of a C-N bond.
Additionally, the O1s spectrum had exhibited peaks at 532.7, 532.0, 531.6, 530.6, 530.3 and 529.9 eV corresponding to
C-O, C=O and Fe-O bonds; while the Fe2p spectrum had displayed peaks at 724.4, 724.4, 711.0 and 712.0 eV indicated
the presence of Fe-O and Fe 3 O 4 . During the process of friction behavior, the metal substrate had acquired a positive
charge, led to the absorption of carboxylate anions in the solution and their accumulation on the metal substrate surface,
formed a molecular brush structure. Meanwhile, the hydroxyl group at the other end of the anion had entered into the
water phase. Under external loads, shearing force was more likely to occur, resulted in a reduction of friction coefficient.
In cases where alcohol amine solution had not absorbed CO 2 , it became difficult for anions in the solution to ionized and
enriched on the metal substrate to form a molecular brush structure, thus hindered effective reduction of friction
coefficient. Additionally, carboxylate ions ware prone to chemical reaction with metal substrates under high shear stress
conditions, led to formation of carbon-based tribofilms and further reduction in coefficient of friction. However, the
tribofilm had poor bearing capacity and was easy to be damaged during the friction process. When the tribofilm was
damaged, the metal substrate strongly bound by anions was taken away, resulting in wear. With the progress of the
friction test, new carboxylate anions ware adsorbed on the metal substrate again, and the above process was repeated
constantly, resulting in increased wear of the metal substrate.
Key words: CO 2 utilization; green chemical; alcoholamine solution; tribological properties; carbon-based tribofilm

[3]
CO 等温室气体的排放已经引起很多严重的环境 之一 . 目前研究了很多CO 的转化方法，比如光催化
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问题 [1-2] ，CO 的转化方法成为了当今解决的重点问题 转化 [4-6] 、电催化转化 [7-9] 、催化化学转化 [10-12] 和生物转
2