Search results

The purpose of this paper is to study the tribological properties of a thiazole derivatives (T561), overbased alkyl benzene calcium sulfonate (T106A) compounded with T561 and overbased alkyl benzene magnesium sulfonate (T107) compounded with T561 in rapeseed oil (RSO).

A four-ball machine was used to evaluate the tribological properties of each compound and their combinations with T561 in RSO. Scanning electron microscopy, EDX and X-ray photoelectron spectroscopy were applied to analyze the tribofilm formed on the worn surfaces.

Results of tribotesting demonstrated that synergistic effects exist between the overbased sulfonates, T106A and T107, and the thiazole derivative, T561. The texts of tribofilm indicated that iron sulfide and iron oxides exist in T561 single agent lubricant film and two composite additives lubricant film, and no sulfates were detected. It suggested that the addition of alkyl benzene sulfonate did not hinder the formation of iron sulfides and iron oxides. Meanwhile, CaSO₄ (MgSO₄) and CaCO₃ (MgCO₃) were detected on the worn surface of the composite additives, which were not detected on the single agent friction surface.

A tribofilm mainly contains CaSO₄ (MgSO₄) and CaCO₃ (MgCO₃) formed on the worn surfaces, which is responsible for excellent extreme pressure and anti-wear properties of the compound agents because of their high melting point and high shear stress.

In this study, alkali calcium sulfonate which is added to engine oils as a detergent‐dispersant was obtained. A definite amount of Ca(OH)₂ and water was added to the mixture of neutral calcium sulfonate (NCS) and spindle‐oil (SO), and the mixture was taken into an appropriate reactor. CO₂‐air mixture was passed through the mixture for definite periods at 85°C and the appropriate parameters affecting the qualities and efficiency of the product were determined. Thus, after the mixture of CO₂+air (having the ratio of 1/8.5) was passed through the mixture of 180 g NCS+600 g SO+60 g Ca(OH)₂+90 g water with the velocity of 108 L/h for 200 min, transparent alkali calcium sulfonate with a total base number value of 28.6 mg KOH/g was obtained.

The aim of this study is to experimentally analyze the friction and wear responses of different steels to different surface films generated in oil-lubricated tribological contacts.

Tribological experiments were conducted using a 100Cr6 bearing ball sliding against a V155 carbon steel disk and 316L stainless steel disk, respectively. Lubricants with additives known to form zinc dialkyl-dithiophosphate (ZDDP) or Ca tribofilms were used.

Both of the ZDDP and Ca tribofilms helped stabilize the friction coefficient of the carbon steel and stainless steel. The ZDDP tribofilm could effectively protect the carbon steel from wear, in contrast to the stainless steel, whereas the wear of both carbon steel and stainless steel could be significantly reduced by the Ca tribofilm. In the case of neither ZDDP nor Ca tribofilms formation, the 100Cr6 ball was worn by the V155 disk and generated a special surface topography. A polishing wear mechanism was proposed to explain the wear of the 100Cr6 ball.

This study clearly shows the different friction and wear responses of steels to the different surface films and the response is dependent on the tested steel.

Metalworking fluids are applied in metal working operations in order to decrease tribological effects and increase economy. Primarily they are used for cooling the tools and the workpieces and also for lubricating the cutting edges. The components of metalworking fluids responsible for decrease in friction are AW/EP additives. To comply with the very strong European legislation for human and environmental protection, important compounds for metalworking fluids formulation are reduced. Based on this, chlorinated paraffin, a widely used AW/EP additive, should be replaced with less harmful compounds. The application possibility of new types of AW/EP additives as chlorinated paraffin replacements is investigated in this paper. These additives are synthetic esters of carboxylic fatty acids, phosphoric and dithiophosphoric acid derivatives. Watermiscible metalworking fluids formulations are prepared with the new types of additives and examined at laboratory test machines–EP‐Four ball, Wear‐Four ball machine and Reichert balance machine.

The purpose of this paper is to describe very reproducible boundary lubrication tests, conducted as part of design of experiment (DOE) to study the behavior of fluorinated catalyst mixed with polutetrafluoroethylene or Teflon (PTFE) in developing environmentally friendly (reduced P and S) anti‐wear additives for future engine oil formulations. The paper presents both the statistical and experimental solution to the fluorinated interactions in fully formulated (F‐fully formulated) and plain ZDDP (F‐plain) oils.

The wear performance of fluorinated additive in combination with conventional commercial oil and ZDDP plain oil were investigated using DOE software. Several chemistry combinations were prepared and tested under extreme boundary lubrication (385 N with maximum Hertzian contact pressure of 2.72 GPa). Wear and frictional properties were evaluated using DOE and the interactions of fluorinated mix with minimum phosphorus were studied and compared with respect to fully formulated and plain ZDDP oils.

The optimized desirability shows the best condition that leads to more consistency in the breakdown of the tribofilm for a fixed contact load and fixed amount of fully formulated ZDDP oil. The influence of catalyst and PTFE fluorinated mix were examined. Scanning electron microscopy with chemistry analysis was developed. Hardness of the tribofilms, X‐ray of the wear track and Auger spectroscopy confirm the present of fluorine and phosphorus.

To ensure the reliability of the model, two original tests were conducted on the fully formulated and plain oil with minimum fluorinated mix.

The purpose of this paper is to study the friction and wear performance of two plain ZDDP oils in the presence of fluorinated catalyst and PTFE combinations under extreme boundary lubrication of 385 Newton load (Hertzian contact pressure of 2.72 GPa). The mechanism of tribofilm formation and breakdown was followed carefully by monitoring the friction coefficient over the duration of the test.

Very reproducible boundary lubrication tests were conducted as part of design of experiment (DOE) to study the behavior of two different fluorinated plain oils in developing environmentally friendly (reduced P atd S) anti‐wear additives for future engine oil formulations. Friction and wear performance of ZDDP plain oils improve in the presence of fluorinated mix combinations. In order to understand the wear mechanism, different factors of chemical compositions and different wear responses were analyzed and optimized using DOE. Several chemistry combinations were prepared and tested under extreme boundary lubrication.

The interactions of fluorinated mix with minimum phosphorus were studied and compared. Tribofilms with thickness ranging from 300‐400 nm were developed during wear tests and were analyzed for two fluorinated plain oils that target reducing phosphorus.

The influence of catalyst and PTFE fluorinated mix were examined. Scanning electron microscopy with chemistry analysis was developed. Hardness of the tribofilms, X‐ray of the wear track and Auger spectroscopy confirm the present of fluorine and phosphorus. The two repeated tests that were conducted on both plain oils with minimum fluorinated mix confirm the prediction of the DOE model.

Compared with traditional industrial processing technologies of sulfurized isobutylene, the one-step synthesis method involving high pressure is more environment-friendly and leads to better product performance. However, products from various sources perform differently because of the difference in the contents of their components. Therefore, the purpose of this study was to investigate the relationships between sulfide components of high-pressure sulfurized isobutylene and load carrying capacities.

A typical high-pressure sulfurized isobutylene was chosen, and the structure and contents of its sulfide components were characterized using gas chromatography-mass spectrometry and gas chromatography (GC). Extreme-pressure properties of the sample at different concentrations were evaluated using a four-ball tribometer.

A multiple regression equation model was established, and tert-butyl trisulfide made the greatest contribution to the extreme-pressure properties according to the equation coefficient, while tert-butyl tetrasulfide had no effect. The results can be attributed to the fact that the structure of a sulfurized additive having an impact is application-specific.

A precise and fast way to predict weld load values of high-pressure sulfurized isobutylene by using GC and the established equation model were successfully developed. Moreover, the empirical equation shows the relationships between sulfide component concentrations and load carrying capacities.

In this study, the conditions of obtaining neutral calcium sulfonate which is added to engine oils as a detergent‐dispersant was studied. For this purpose, post‐dodecyl benzene sulfonic acid, obtained from post‐dodecyl benzene which remains as the bottom product during the production of dodecyl benzene sulfonate was used as the initial substance. Additionally, the reactor to be used in the production of neutral calcium sulfonate was designed and the amounts of spindle‐oil, toluene, raw sulfonic acid solution and Ca(OH)₂ used during neutralization were determined.