2. Two approaches:
1. Creating micro/nano - hierarichical structures for eg: electrochemical deposition, phase
separation, emulsion, electrospinning, immersion, CVD, wet chemical reaction, lithography.
2. Chemical modifying a - hierarichical structures surface with a low surface energy eg. Fatty
Acids, polymers, HCs, FluoroCarbons
3. Dip Coating :
• Production of Nano metric thick coatings
• continuous process in which substrate is immersed into solution of
the material to be deposited at a constant immersion rate, & then it
pulled up.
• Film is deposited on substrate while pulled up.
• Withdrawal & Pulling Speed controls thickness of film.
• Solvent present in solution evaporated & result in coating surface.
4. Dip Coating :
Advantages
• Simultaneous coating of top and bottom part of substrate, no
wastage of material, suitable for all kind of materials, high output,
uniform, highly durable, compact, stable coatings, and easily
repairable.
5. Dip Coating Technique:
• Carried out a simple dipping process for the preparation of super
hydrophobic coatings based on titanium dioxide nanowires dispersed
in tetrahydrofuran (THF) followed by the addition of
polydimethylsiloxane (PDMS).
6. • Hwang et al. (AppliedSurfaceScience, 2014,288:619-624.) obtains
hydrophilic pattern by the method laser machined at aluminum super
hydrophobic surface.
• Contact angle more than 150 °, the roll angle surface less than 10 ° be
called super hydrophobic surface.
• Super hydrophobic surface, owing to having superior repellency
energy, has significant application value in fields such as automatically
cleaning, drag reduction, freezing and oil-water separation.
• At present, the hydrophilic pattern of super hydrophobic surface
realizes mainly through technology such as photoetching, laser
irradiation, Soft lithograph and Cement Composite Treated by Plasma.
7. • invent a kind of micro-pattern processing method of adhesion
controllable hydrophilic, by micro-Milling Process technique, processing
the controlled hydrophilic Wei Keng of adhesion, micro-channel pattern
at Metal Substrate super hydrophobic surface, the method has that cost
is low, simple to operate, control accuracy is high and the advantage such
as the hydrophilic persistency of pattern is good.
8. A kind of micro-pattern processing method of adhesion
controllable hydrophilic, step is as follows:
• Super-hydrophobic sample is fixed on micro-milling machine workbench, ensure
that its super hydrophobic surface is parallel with micro-milling working table
locating surface, note is perpendicular to the Z axis that super hydrophobic
surface direction is XYZ coordinate system of super-hydrophobic sample, the
height rotating main shaft installed on Z axis by controlling system to reduce,
makes rotary milling tools incision super hydrophobic surface and applies X/Y
plane motion according to demand；Wherein, rotating the speed of mainshaft
more than 60r/min, milling cutter diameter is more than 50 μm, and milling
depth is more than 10 μm, it is thus achieved that hydrophilic micro-hole or
micro-raceway groove water droplet is had adhesion or anisotropy adhesion, and
this adhesion has permanent；The adhesion of water droplet is realized
quantitatively regulating and controlling by hydrophilic micro-hole diameter by
hydrophilic micro-hole, hydrophilic micro-raceway groove to the anisotropy
adhesion of water droplet by micro-channel width quantitatively regulating and
controlling.
10. • Wieland Wicoatec (Company)
• The SiO2-based coating forms a very thin separating layer between
the metal surface and the medium flowing through. Thus, wico®pure
ensures clean media on the one hand and protects the metal
substrate from corrosion on the other.
• https://www.youtube.com/watch?v=GTq__iTgSoI
11. • Recently, some achievements on the creation and characterization of
stable super-hydrophobic surfaces on stainless steel have been made [20–
23]. In 2005, Shen et al. coated a uniform TiO2 nano-particle film on the
surface of 316L stainless steel by means of sol–gel and dip-coating
technology, and then used fluoroalkylsiane to fabricate the surface to
enhance the surface hydrophobic property.
• . In 2006, Kim and co-workers reported the room temperature synthesis of
dip coated water repellent silica coatings onto stainless steel substrates
using 1,1,1,3,3,3-hexamethyldisilazane as a surface modify agent.
• Jagannathan et al. developed an atmospheric process based on
compressed CO2 that can create stable clusters of small organic molecules
and these organic clusters can assemble thin film on stainless steel
substrate to create the super-hydrophobic material.
• In 2007, Nema et al. reported a novel approach to grow nano-structured
Teflon-like super-hydrophobic coatings on stainless steel
12. Preparation of super-hydrophobic surface on
stainless steel
we utilize the electroless plating technology to prepare the Nicoated on
stainless steel surface with micro- and nano-meter scale binary
structures, and then modify the resulting surface by virtue of the
lowsurface energy material HFTHTMS to produce our target super-
hydrophobic material. As we know, the electroless plating is a
considerable useful technology that does not need expensive
apparatus and has no requirement for the shape of the substrates. Our
experimental results have proved that the Nicoating stainless steel
surface with micro- and nano-meter scalebinary structures can be
obtained using the electroless plating.Moreover, the Ni-coating is
tightly combined with the substrate. In addition, the Ni-coating can
protect the stainless steel from eroding.
13. Specific process of preparation is as follows. (a)Pretreatment of the
stainless steel substrate: a sheet of stainless steel was sandblasted with
200 um silicon dioxide under the pressure of about 0.4 MPa for 30 s (the
distance between the nozzle and the surface is about 8 cm) and
ultrasonically cleaned in acetone and deionized water, respectively, and
then immersed in 5% HCl solution for 10 min. (b) Process of electroless
plating: the acidized stainless steel was immersed in plating bath solution
(0.1 mol/L NiSO46H2O + 0.25 mol/L N2H4) for 4 h at 80 8C and the pH
value of the plating bath solution was adjusted to 8–10. Finally, the sheet
was immersed in 1 103 M HFTHTMS ethanol solution for 24 h at room
temperature and dried at 120 8C for 2 h in an oven. Here, HFTHTMS
represents (heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane,
and its chemical formula is C13H13F17O3Si.
14. Fabrication of hydrophobic Ti3SiC2 surface with micro-
grooved structures by wire electrical discharge machining
• A commercial WEDM system (Sodick, AP250LS) was used to fabricate micro-grooved
Ti3SiC2 surface.
• Commercially available Ti3SiC2 bulk was firstly cut in 15×15×5mmbar and fixed on the
vertical worktable.
• The brass wire with the diameter of 50 μm was loaded as an anodic electrode and
constantly controlled by wire electrode feeding system to minimize the electrode wear.
• The workpiece was immersed into the dielectric oil (Glysantin G 48–24) during the
machining process. Under the action of micro electrical discharge removal, the micro-
grooved structures were machined by the wire electrode along the setting V-shape
excision path.
• All the experiments were implemented under same electrical discharge parameters.
discharge voltage and inter-electrode gap were set as 70 V and 0.034 mm, respectively.
Afterwards, these machined samples were cleaned ultrasonically by acetone and alcohol
for three times.
15. Analysis work after Wire EDM
• The phase constitutions of Ti3SiC2 surfaces before and after WEDM processing
were analyzed by energy dispersive X-ray spectroscopy (EDS, INCAP FET-X3), X-ray
diffraction (XRD, MiniFlex600, Rigaku), Raman spectrum (HR Evolution, Horiba)
and X-ray photoelectron spectroscopy (XPS, Axis Ultra DLD, Kratos). The surface
topographies were characterized by scanning electron microscope (SEM, Quanta
FEG450, FEI) and 3D laser scanning confocal microscope (VK-250, Keyence).
According to the measured 3D topography and profile, the groove width b,
groove depth h and surface roughness Ra.
