contains a minimum of 12% Cr to aid in the formation of
protective surface layer which resists corrosion in a wide range
of environments but is also less susceptible to sensitization and
more resistant to chloride-assisted corrosion due to its lower
carbon content and alloyingwithMo andMn.Whereas SS316Lis
a conventional alloy, Nitinol is a less-utilized alloy which has
gained popularity in the field of biomaterials due to its shape
memory property and corrosion resistance.
45-47
Modifying these
substrates has been proven to be challenging perhaps because
only some of the surface species in the alloy reactwith the organic.
On other metal oxide surfaces incomplete film coverage has been
attributed to many parameters including low hydroxyl content,
surface roughness,
48,49
and surface defects.
49
In this study, monolayer formation on the alloy oxide surface
of SS316L andNitinol was compared tomonolayer formation on
the constituent metal oxide surfaces, iron, nickel, titanium,
chromium, molybdenum, and manganese by long chain aliphatic
acids with various headgroups (sulfonic acid, phosphonic acid,
hydroxamic acid, and carboxylic acid). The extent of monolayer
formation in these systems was studied by diffuse reflectance
infrared Fourier transformspectroscopy (DRIFT),matrix-assisted
laser desorption/ionization time-of-flight mass spectrometry
(MALDI-TOF MS), contact angle goniometry, and atomic force
microscopy (AFM), in order to elucidate the role of constituent
metalsandheadgroupinmonolayerformationonalloys.
Experimental Section
Materials. Stainless steel foils (SS316L, 99.99% pure), mo-
lybdenum foils (99.9%pure), iron foils (99.5%pure), nickel foils
(>99% pure), and titanium foils (>99% pure) of 0.25 mm
thickness were obtained from Goodfellow Inc. Chromium
pieces of 1-6 mm size (99.998% pure) and manganese pieces of
3-12 mm size (99.99%pure) were obtained from Kurt J. Lesker
Co. Nitinol foils (NiTi, 51% nickel:49% titanium; 0.008 in.
thickness,>99.0%pure)were purchased fromJohnsonMatthey,
Inc. Tetrahydrofuran (Optima grade), methanol, and octadecyl-
carboxylic acid (ODCA, 98þ%) were obtained from Aldrich
Chemical Co. Tetrahydrofuran (THF) was distilled over sodium
and stored under nitrogen. Octadecylphosphonic acid (ODPA,
98%) was obtained from Alfa Aesar. Octadecylhydroxamic acid
(ODHA) was synthesized in the laboratory as previously
reported.
16
Sodium 1-octadecanesulfonate (97%) was obtained
from Fluka and acidified using hydrochloric acid to form the
corresponding acid. The octadecylsulfonic acid (ODSA) formed
was then analyzed by IR, mass spectrometry, and NMR. Hydro-
chloric acid (ACS Certified Plus) was purchased from Fisher
Scientific and used without further purification.Equipment. All diffuse reflectance infrared spectroscopy
(DRIFT) measurements were performed on a Nexus 470 FTIR
equipped with a diffuse reflectance attachment from Thermo
Electron Corp. Contact angle measurements were obtained on a
VCA Optima goniometer. Atomic force microscope (AFM)
images were taken on a PicoSPMfromMolecular Imaging Corp.
(Agilent Technologies). Mass spectra were collected on a high-
resolution atmospheric pressure time-of-flight mass spectrometer
purchased from Agilent Technologies.
Substrate Preparation and Monolayer Formation. Stain-
less steel 316L (SS316L), Nitinol (NiTi), iron, nickel, titanium,
and molybdenum substrates were cut into 1 cm  1 cm coupons
and sanded using 220, 320, 400, and 600 grit silicon carbide
papers. Manganese and chromium pieces were ingots and there-
fore not sanded because of their morphology. All substrates were
cleaned by ultrasonication in methanol (15 min) followed by 反应釜内胆材料316L合英文文献和中文翻译(3):http://www.751com.cn/fanyi/lunwen_8688.html