We suppose that the formation of such directed microstructure on a surface of samples will create conditions when closed vacuum valleys in the contact zone either will not be formed at all or will be easily and quickly devacuumized. As a result, it should lead to substantial reduction friction force and surface wear. Figure 3 Special surface structure consisting of parallel grooves proposed for wear reduction. Experimental study Ball-bearing
steel grade ShH15 (according Geneticin manufacturer to the standard GOST 801-78) produced by electroslag remelting has been chosen as a material for fabrication of samples. It has international analogues: American AISI Type E52100, UNS G52986, European 100Сr6, and Japanese JIS SUJ2. This high-carbon chromium steel features high hardness, high mechanical strength, and dimensional stability. Tribological tests were carried out on the friction machine with a fixed CP673451 in vivo flat-surface sample and a rotating cylindrical counterface sample. The oil IMP-10 was used as a lubricant. A special technique for forming grooves on a sample surface with specified 3D geometry was developed. Initially, the surface of the sample was polished to a level of roughness with Ra about 0.02 μm. Then, diamond paste with size of a grain corresponding to the desired depth of grooves
was applied. Movement www.selleckchem.com/products/yap-tead-inhibitor-1-peptide-17.html of a polishing plane with diamond paste was performed only in one direction. Polishing with the paste actually led to controllable scratching of the surface. Polishing movements were repeated only a few times to preserve the initial nano-topography of the surface between grooves. Intermediate results were checked by the laser differential phase profilometer  and scanning electron microscope. As a result, ten flat samples with directional grooves had been fabricated. The depth of grooves was varied in the range
Temsirolimus price from 0.3 to 2.6 μm. Rotating cylindrical counterface had no grooves on it, and surface roughness was the same as the initial roughness of samples Ra = 0.02 μm. A multistage testing technique which mimics operation conditions of real friction units was developed. The testing procedure of each sample included the following: (1) three initial run-in stages, in which the formation of secondary structures on friction surfaces occurred; (2) the final test stage, during which tribological and rheological characteristics of a friction samples and lubricant were estimated. Each of the initial three stages was run until a length of friction equals L = 500 m. The final measurement stage had a length of friction L = 3,000 m. Ambient temperature was 20°С. Axial load 1,250 N was big enough to maintain permanent wear but not to allow plastic deformation of material.