Four-ball wear test

Wear scar (ASTM D4172 method four ball wear test). The antiwear performance was evaluated by the diameters of the wear scars in four-ball wear tests. The borate-detergent RMs showed better anti wear performance as compared with those of the carbonate-detergent RMs. Interestingly, the antiwear performance was dependent on the detergent type in the case of carbonate-... 

Some of these carboxylic acid salts, such as 3-iodo-4-methosxybenzoic acid, have been reported to have load-bearing capacities in an aqueous solution of 0.98 (megapascal) MPa at 200 rpm with a four-ball type lubrication oil testing machine [4], A four-ball wear test (ASTM D-4172) is a test used in the petroleum industry that determines the wear characteristics of a lubricant. In this test, three balls are clamped together, covered with the lubricant being analyzed, and rotated with a fourth ball under a load. Inputs can be varied by temperature, pressure, revolutions per minute, and duration. 

Figure 11-7. Influence of acidic constituents on the additive activity of tricresyl phosphate. Four-ball wear test 1 hour at 620 rpm. Reference lubricant 0.065% tricresyl phosphate in rust-inhibited mineral oil. <0.02 Mole-% acidic constituent in tricresyl phosphate . 0.1% Mole-% acidic constituent in tricresyl phosphate o. 0.3 Mole-% acidic constituent in tricresyl phosphate A. From data by Bieber, Klaus and Tewksbury [41].

Forbes and Silver [40] made a systematic comparison of organic phos-phonates, phosphates and phosphinates based on the results of the 60-minute four-ball wear test under a 15 kg load at 1500 rpm. On plotting the wear data for n-butyl di-n-octylphosphinate, di-n-butyl n-hexylphosphonate, di-n-butyl phenylphosphonate, diethyl benzylphos-phonate, diethyl o-nitrophenylphosphonate and tri-n-butyl phosphate against the ionization constants of the corresponding parent acids (expressed as pK ), the solid curve of Fig. 11-10 was obtained. This led them to the hypothesis that the involvement of carbon-phosphorus bonding... 

Figure 11-12. Influence of the metal ion on the additive action of dialkyl dithiophosphates. Four-ball wear test at 15 kg load, 1500 rpm. Additive furnishes 4 mmoles P per 100 gms white oil solution. a Bi(IIl). b Sn(II). c Sbdil). d Pbdl). e Ag(I). f Fedll). g Nidi), h Cd(ll). k Zn(ll). Data by Allum and Forbes [58].

Figure 11-17. Four-ball wear tests of ester-disulfide additives. Wear test 30 minutes at 15 kg load, 1500 rpm. Additives 18.52 mmoles/100 gms. A C2H500C(CH2) SS(CH2)j COOC2H5. 0 Base oil. B Diethyl seba-...

A four-ball wear test machine is used to determine a coefficient of friction of lubricants." Three metal balls having diameter of 12.7 mm are clamped together and the fourth ball of the same diameter is rotated on these balls under pressure of 98.1 N with a speed of 600 rpm for 10 min. The temperature of the test lubricant is 75°C. At the end of the 10 min interval, the coefficient of friction is measured. The measurements are repeated for successive 10 min intervals until frictional trace indicates incipient seizure. 

ASTM D5183-05(2011) Standard Test Method for Determination of the Coefficient of Friction of Lubricants Using the Four-Ball Wear Test Machine. 

The flash temperature is also related to types of tribomachines. Each type of machine has its specific type of contact geometry and style. For example, on a four-ball lubricant testing machine, the flash temperature is totally different from that of a sliding pin on disk. The A7max temperature for a standard four-ball wear contact may be calculated from a Blok equation 18... 

The work of Forbes and Battersby [46] is an integrated study of the relations among the chemical structures of the dialkyl phosphites, their adsorption on and reaction with iron, and their behavior in four-ball bench testing of lubricant additive effectiveness. The four-ball data in Table 11-17 for solutions of additive in white oil show that both the wear/load index (mean Hertz load) and the initial seizure load are critically responsive to concentration, with a strong effect when the concentration increases from 0.01 to 0.04 molal (0.031% to 0.124% P). The initial seizure load is an uncomplicated criterion with a straightforward interpretation, whereas the wear/load index is contrived, both in concept and performance. The low-load 50 minute wear data show inconsistencies in the influence of additives that have not been explained. 

Wear spot diameter under conditions of hydrodynamic friction and critical seizure load were determined on a four-ball friction testing machine with steel balls of 0.017 mm diameter and a rotation speed of 1 500 rev/min [2]. 

FIGURE 21.7 Four-ball sequential test total wear at 60 min. 

FIGURE 21.8 Four-ball sequential test friction data, segment 1 (wear-in). 

From this test, antiwear and extreme-pressure data were determined, such as welding load, load wear index and wear scar diameter under a load of 40 decanewtons (daN), 60 daN and 80 daN, respectively. First, evaluations were performed on the three original nonmodified hard-core RMs, then evaluations were performed on the sulfur-functionalized ones. Four-ball test data (results only for one concentration 10 wt% additive) are summarized in Table 3.9 (Delfort et al., 1995 and 1999) for ... 

Modified hard-core RMs by phosphosulfurized compound. Improved extreme-pressure and antiwear properties have also been obtained with the introduction of some chemical species, such as sulfur, phosphorus or boron derivatives, into the colloidal core (Delfort et al., 1998 Inoue, 1993 Inoue and Nose, 1987). Welding loads, load wear index and wear scar diameter at 5 wt% of a CaC03 core surrounded by a calcium alkylaryl-sulfonate surfactant shell, and modified by phosphosulfurized calcium carbonate core were evaluated for calcium dialkyl dithiophosphate (CaDTP) and calcium trithiophosphate (CaTTP) with the four-ball extreme-pressure test (ASTM D2783 standard method). Both modified products exhibit improved extreme-pressure performances (welding load and load wear index), while their antiwear properties (wear scar diameter) compared to those of the original micellar substrate remain at least at the same level. 

A combination of ZDDP and hard-core RMs leads to a synergistic effect of metallic detergents on the degradation of ZDDP. These phenomena are observed in many tests and can be explained in terms of (a) the acid neutralization property of hard-core RMs that leads to the prevention of decomposition of ZDDP (in the valve train wear test and the thin film oxygen uptake test), (b) the competitive adsorption of detergents that reduce the effective concentration of ZDDP on the metal surface (in the four-ball test), (c) the formation of mixed films on the metal surface, formed through the decomposition of ZDDP in the presence of hard-core RM s (the coefficient of friction in the Falex wear test). 

XRF The four-ball test wear surface after thermal decomposition was composed mainly of Zn, S and P (Rounds, 1975). 

Test which is used to determine the relative wear-ball preventing properties of lubricants under boundary test lubrication conditions. Two values are reported - load wear index and weld point from two procedures EP test ASTM D 2596 and wear test ASTM D2266. There are four steel /2-inch balls. Three of the balls are held together in a cup filled with lubricant while the fourth ball is rotated against them. Resistance to motion. 

Apart from the frictional effects, two other performance characteristics need to be considered, namely load-carrying capacity and wear. Most of the available information on these subjects has been obtained from the practical use of commercial materials and will be discussed later, but Groszek and Witheridge found that molybdenum disulphide ground conventionally in air gave a small increase in Mean Hertz Load and Weld Load in a Four-Ball Test as 5% dispersions in a mineral oil. However, oleophilic molybdenum disulphide, ground in n-heptane, gave a 170% increase in Mean Hertz Load and a 260% increase in Weld Load. 

Not only can molecular design improve the miscibility with other oils, it can also confer ILs with special functions, such as antioxidation and the ability to adapt to a broader temperature range. We synthesized three imidazolium-based ILs containing sterically hindered phenol groups with antioxidant functions and evaluated the tribological behaviors of these ILs as additives for PEG appfication in steeFsteel contacts on an Optimol SRV-IV oscillating reciprocating friction and wear tester, as well as on MRS-IJ four-ball testers [100]. The rotary bomb oxidation test (RBOT) test, thermal analysis, and Cu strip test results revealed that synthesized ILs possessed excellent antioxidation capability. 

T. Singh and V.K. Verma, EP activity evaluation of tris(N-arylthiosemicarba-zido)-molybdenum (III) on steel balls in a four-ball test, Wear, 146, 313-323, 1991. 

Figure 10-17. "Friction polymer" at rubbing surfaces. (a) Wear scar on stationary ball of four-ball test, leading edge at bottom run in cyclohexane vapor. Fein and Kreuz [50]. (b) Wear scar on conically-ended pin, leading edge at bottom run in white oil. Dorinson, unpublished work. (c) Wear debris in polymer matrix as found in the lubricant. Dorinson, unpublished work.

When tested in the four-ball machine, solutions of sulfur in petroleum oils of moderate viscosity or in white oil raise the critical load for the onset of severe, destructive wear, which is designated as "antiseizure" action in the technological idiom of the four-ball test. Davey [54] found a significant increase in the critical initial seizure load from 834 N (85 kg) for a petroleum base oil to 1275 N (130 kg) for elemental sulfur dissolved in the oil. Sakurai and Sato [55] observed a 3.2-fold increase in the load-wear index (mean Hertz load) for a 0.5 weight-percent solution of elemental sulfur relative to that of the uncompounded white oil. The load-wear index is a specialized result of the four-ball test that can be taken as indicative of the average antiseizure behavior of the lubricant. Mould, Silver and Syrett [56] reported a load-wear index ratio of 3.08 for 0.48% sulfur in white oil relative to that of the solvent oil, and also an increase in the initial seizure load from 441 N to 637 N (45 kg to 65 kg) and in the 2.5-second seizure-delay load from 490 N to 833 N (50 kg to 90 kg). 

Reid [26]. But the low-load one-hour wear data, also listed in Table 11-8, are not in the same relative rank order as the EP data. Because of the empirical and arbitrary character of the four-ball test, it is probable that the contact and rubbing parameters have not been identified precisely enough for a quantitative formulation of the mechanism of additive action. 

Systematic data on the relation between chemical structure or reactivity of chlorine compounds and lubricant additive performance are sparse. Table 11-11 gives some four-ball test data obtained by Mould, Silver and Syrett [35], with the additives listed in order of increasing effectiveness in terms of the wear/load index. The results show numerous departures from expectations based on chemical structure. For example, there is practically as much difference between the wear/load indices for the two primary chlorides, n-hexadecyl (16.2 kg) and n-hexyl (30.4 kg), as for n-hexyl chloride and t-butyl chloride (46.1 kg). A large difference would be expected on the basis of chemical reactivity between the additive effectiveness of primary and tertiary alkyl chlorides, but only a small difference for the two primary aliphatic chlorides. The overall trends are what would be expected in general, primary and aromatic chlorides are less efficacious than secondary chlorides, which in turn... 

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