Quality index of the lubricating oil can be divided into two categories: one is oil physical and chemical performance indicators, another kind is the application of oil performance metrics.
This paper mainly introduces several major physical and chemical indicators)
Color: the color of the lubricating oil and all substances, all have the corresponding and fixed color, it and the base oil of essence of system and related additives.
But in the process of use or storage is due to its oxidation metamorphism, so as to change the color, and the degree of color change related to metamorphic grade.
Such as white, said to have water or air bubbles exist;
Color is darker, the oxidation or pollution.
Viscosity, viscosity of lubricating oil is the degree of internal friction resistance, i. e. the inner friction measurement.
Viscosity is usually divided into dynamic viscosity, kinematic viscosity, relative viscosity of three.
Viscosity is all kinds of lubricating oil classification, grading, quality evaluation and selection, and the major indexes of the substitute.
Dynamic viscosity, dynamic viscosity is liquid flow under certain shear stress, a measure of the internal friction.
Relative viscosity, relative viscosity was measured by using different specific viscometer viscosity conditions of units, generally good's viscosity, saybolt viscosity, viscosity redwood said three kinds of methods.
Kinematic viscosity, kinematic viscosity is liquid, when gravity flow, a measure of the internal friction.
The measuring unit was/s;
Our country will be divided into lubricating oil viscosity according to the size of the 20 grades, called viscosity grade.
GB/T3141 - ISO viscosity grades
1994 40 ℃ intermediate point kinematic viscosity of 40 ℃ kinematic viscosity range 2 2 2.
2 to 1.
42 3 3 3.
52 5 5 4.
14 ~ 5.
6 7 July 6.
12 ~ 7.
48 10 10 10 9 ~ 11 15 15 15 13.
5 to 16.
22 22 22 May 19.
8 ~ 24.
2 32 32 28.
8 ~ 35.
2 46 46 46 41.
4 ~ 50.
6, 68, 68, 68, 61.
2 ~ 74.
8, 100, 100, 100, 90 ~ 110, 150, 150, 150, 135 ~ 165, 220, 220, 220, 192 ~ 242, 320, 320, 320, 288 ~ 352, 460, 460, 460, 414 ~ 506, 680, 680, 680, 612 ~ 748, 1000, 1000, 1000, 900 ~ 1100, 1500, 1500, 1500, 1350 ~ 1650, 2200, 2200, 2200, 1980 ~ 2420, 3200, 3200, 3200, 2880 ~ 3520 is an important quality index of lubricating oil viscosity, viscosity is too small, can form a half liquid lubrication or boundary lubrication, thus accelerate the friction pair wear, and also easy to leak;
Viscosity is too large, liquidity is poor, poor permeability and heat dissipation and internal friction resistance is big, super hard, consumed power.
Therefore, choose the viscosity, friction pair is the assurance of sufficient lubrication.
Viscosity-temperature characteristics: the characteristics of lubricating oil into the viscosity-temperature characteristics with temperature changes.
The multi-purpose viscosity index Ⅵ said the stand or fall of viscosity-temperature characteristics.
Ⅵ value of oil, the greater the commonly said its viscosity change with temperature, the greater the more suitable for use in a wide temperature changeable or occasion.
The better the oil viscosity-temperature characteristics.
Oil with 0 Ⅵ Ⅵ = 0, said Ⅵ = 100 oil in 100 Ⅵ said.
Viscosity index is an experience, it is to use viscosity performance is good,
Viscosity index is 100)
Poor and viscosity properties (
Viscosity index as 0)
Two kinds of lubrication oil for the standard, to 40 ℃ and 100 ℃ for viscosity as a benchmark to compare.
Solidifying point and pour point condensation point: condensation point refers to the oil under the cooling conditions prescribed by the stop of the highest temperature;
Pour point, pour point refers to the oil under the conditions stipulated in the minimum temperature cooled to still can continue to flow.
Low temperature properties of lubricating oil solidifying point and pour point said, but what is better to reflect oil pour point low temperature fluidity, actual use is better than solidifying point, therefore, in the world at present is mainly by pour point of lube oil low temperature performance.
Pour point about 3 ℃ higher than the freezing point, generally the lubricating oil temperature is higher than pour point 3 ~ 4 ℃.
Lightning: flash point refers to the provisions of the conditions, heat the oil, the evaporation of oil vapor and air mixture, to a certain concentration to produce a brief flash when in contact with the flame is burning the lowest temperature.
Acid value, acid value refers to neutralize 1 g oil contains organic acids required for the quality of potassium hydroxide, unit mgKoH/g.
Acid value oil on the new and old oil different meanings.
For the new oil, acid value oil refining depth, for 110 oil, acid value, indicates the degree of use of lubricating oil in the process of the oxidation.
Acid value is too large, said the oxidation.
Percentage of moisture, moisture is refers to the quality of water content in lube oil.
Due to the presence of water, when the temperature dropped below 0 ℃ worsened viscosity-temperature characteristics, when the temperature rise, the water will be boiled, bubble destruction of oil film, make the oil emulsion, results in the decrease of viscosity, poor lubrication effect change.
Mechanical impurities: all solid impurity in the suspension and precipitation in the lubricating oil referred mechanical impurities, and the presence of mechanical impurities can destroy the lubricating oil film, accelerated wear of friction pair.
Residual carbon: residual carbon is refers to the oil under the condition of going into the air heating, evaporation and decomposition, and finally generate coke residue, expressed as a percentage of the oil.