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Investigation of the Effects of Boron Additives on the Performance of Engine Oil
...Chemically,
boric acid is a very mild, nontoxic acid. It is water soluble (about 6 wt% at room temperature).
The layered crystal structures of boric acid, boron, oxygen, and hydrogen atoms
are strongly bonded to one another to form extensive atomic layers.
Note that each boron atom is bonded to three oxygen atoms to form triangular BO3 groups. Hydrogen links the planar BO 3 groups to one another.
Bonding within the layers is mainly covalent, ionic, and hydrogen,
but between the layers, it is [weak] van der Waals type.
The layers are 0.318 nm apart (Erdemir (6)).
Micro to nanoscale boric acid particles can be prepared using a variety of methods and mixed with oils and greases to achieve higher degrees of lubricity.
In fact, such mixtures have been prepared in the past and their very unique lubrication capacities have been demonstrated (Erdemir (6)).
Just like other solid lubricants (such as MoS 2 , graphite, hexagonal boron nitride),
boric acid owes its lubricity to a lamellar or layered crystal structure.
In general, all of these lubricants are
able to shear very easily along their crystalline shear planes and thus provide low friction.
The atoms lying on each layer are closely packed and strongly bonded to one another, whereas the layers themselves are wide apart, and the forces that hold them together are weak van der Waals type (Erdemir (6), (15)).
Without the boric acid particles, the friction coefficient of base oil is around ∼0.15. When base oil is blended with nanoscale boric acid particles, the friction coefficient is reduced to 0.04.
The effect of sliding velocity on lubricity of nano boric acid–containing oils is provided.
As is clear,
the beneficial effect of nano-boric acid powders on friction becomes very clear
even at very low sliding velocities.
Because of their layered structure, they can shear easily to provide low friction (Erdemir (6)).
In D ¨uzc ¨uko ˘glu and Acaro ˘glu’s study (D ¨uzc ¨uko ˘glu and Acaro ˘glu (18)), vegetable oil–based canola oil and boric acid were combined and their wear performance was investigated. In the experiments, the wear performance of commercial mineral
oil, pure canola oil, and a combination of canola oil and boric acid were compared using a pin-on-disc test apparatus (at a constant speed of 1.5 m/s and under various weights of 60, 120, and 180 N).
It was found that the layered structure of crystalline boric acid particles enables them to slide over each other with relative ease and can reduce friction and wear...
Diesel Engine Test Results
...
Experiments were also carried out for both optimum concentration ratios
using a 170-kVA alternator John Deere diesel engine.
This is a heavy-duty diesel engine and has a four-stroke, water-cooled, direct injection fuel system.
It has flexible fuel connection hoses and a sump oil drain valve.
Moreover, a control supervision and protection panel was mounted on the generator set
base frame.
The control panel was equipped with the following instruments: three ammeters, run meter hours, a volt–frequency meter (by LED) and selector switch, engine oil pressure gauge,
engine coolant temperature gauge, etc.
Fig. 5 shows fuel consumption as a function of engine speed during lubrication by 4 wt% hBN and 4 wt% BA additives running idle (under a load condition of 7%).
The effect of boric acid and boron nitride additives on the amount of fuel consumption was compared with the base oil, as seen in Fig. 5.
Diesel engine tests were performed during 1 h of work for base oil and boron additives, and fuel consumption as a function of diesel engine speed was recorded.
The results indicated that the fuel consumption increased with increasing rotational speed
of the engine as expected.
In addition,
the boron compound had a greater reducing effect on the fuel consumption at relatively higher speeds.
To compare with the base oil, additives had a decreasing effect on the fuel consumption.
In addition, 4 wt% BA had a greater reducing effect on the fuel consumption than that
4 wt% hBN.
As shown in Fig. 5,
using the base oil in the diesel engine alone, the average fuel consumption at all test speeds was 17.315 L/h.
For the 4 wt% hBN and
4 wt% BA additives, those values were 16,864 and
16.696 L/h, respectively.
It can be seen that with the addition of 4 wt% hBN and
4 wt% BA, the fuel
consumption was reduced to 2.7 and
3.6%, respectively...
https://sci-hub.ru/10.1080/10402004.2014.909549