The Influence of Friction Deformation on the Microstructure and Hardening of Beryllium Bronze

The peculiarities of the microstructure and properties of BrBNT1.7 beryllium bronze tape samples were studied: the samples were subjected to dispersion hardening as a result of quenching in a supersaturated solid solution and aging. Friction deformation in a dry friction mode provides additional effective hardening while maintaining increased plasticity (bending-and-unbending test).

Dry Sliding Behavior of Qbe−2 Beryllium Bronze against 38CrMoAlA Steel in Pneumatic Downhole Motor under Different Loads

In drilling engineering, the wear of tribo−pairs is the primary cause for the rapid failure of rotating seals in pneumatic downhole tools. In order to reduce the wear of tribo−pairs, a new type of rotating seals was designed in this work, which introduced copper alloys between the stator and rotor. To elucidate the wear and failure mechanism of the copper−steel tribo−pair rotating seals in pneumatic downhole motors, pin−on−disc dry sliding tests with Qbe−2 beryllium bronze pin against 38CrMoAlA steel disc under different loads were thus designed to simulate the friction and wear behavior of such tribo−pair. During the dry sliding process, the friction behavior of the copper pin would go through a running−in period and then become stable. As the load increases, the running−in period will be shortened, while the friction coefficient during the stable period decreases. Interestingly, a false stability occurs when the load is low. However, this phenomenon will disappear under heavy loads. The wear mechanism of the copper pins would change from adhesive wear to ploughing wear as the load increases, which is mainly related to the spalling of asperities and the filling of wear debris into the steel disc. The wear debris consists of copper and copper oxide. The surface roughness of the steel disc and copper pin decreased and the size of the wear debris increased with the increase of the load. The material removal mainly occurs on the copper pin, which will present a relatively small value under 45 N. On contrast, due to the filling of wear debris, the volume of the steel disc increased. Therefore, considering the value and stability of friction coefficients, as well as the wear amount of the sample, it would be better that such tribo−pair could work under 45 N. The present work will provide a fundamental understanding and solid support for systematically designing the tribo−pairs in pneumatic downhole tools under practical working conditions.

The Microstructural Peculiarities of Beryllium Bronze after Heat Treatment

In this article, the microstructural peculiarities and properties of dispersion-hardened beryllium bronze with Ni and Ti are studied after quenching (780 °C) in a supersaturated solid solution and aging (320 °C, 3h). Decomposition of the α-solid solution matrix is implemented by means of an intermittent reaction with a primary allocation intermetallic χ-phase (type Be12Ti) with a VCT-lattice. It is shown that the strength properties (yield strength, micro-hardness) of the alloy more than double after aging.

Development of resource-saving and environmentally safe beryllium bronze soldering technology

The composition of the solder, which provides the necessary technological properties of the product, namely, electrical conductivity and mechanical strength of the junction was selected. The possibility of brazing beryllium bronze with a silver contact plate by furnace brazing using fluxes based on NaCl: CaCl2: CaF2 salts, respectively (24: 61: 15% mass) in the atmosphere was established. The possibility of brazing BrB2 beryllium bronze in the atmosphere using a research flux based on the eutectic of the NaCl – CaCl2 system (28…72% wt.) adding 15% CaF2 over a copper layer is shown. The technology for brazing beryllium bronze BrB2 with silver contact plates with silver solder PSr68 has been developed. The brazing process is combined with the hardening operation, which allows avoiding additional thermal operations; flux residues are removed during hardening and do not actually need additional cleaning operations; applied solder, flux components and technologies for applying a layer of copper are not scarce and relatively cheap, which can significantly reduce the cost of the product, subject to the requirements of the technical specifications. A technological process that makes it possible to refuse of using vacuum systems and toxic fluxes has been developed.

Effects of femtosecond laser texture on the tribological properties of 20CrNiMo/beryllium bronze tribo-pairs of rock bit sliding bearings under non-Newtonian lubrication

In this paper, the tribological characteristics of the unit tribo-pairs of rock bit sliding bearings under various loads and high temperatures were investigated. The conical textures, distributed in beryllium bronze surfaces with depth–diameter ratios ranging from 0.087 to 0.483, were fabricated using femtosecond laser irradiation. The friction characteristics of the 20CrNiMo/beryllium bronze tribo-pairs were tested at a high temperature of 120 ℃ and under non-Newtonian lubrication conditions using pin-on-disc configurations. The textured surfaces with depth–diameter ratios of 0.165 and 0.483 exhibited excellent lubrication and wear-resistant properties. In addition, the effects of the operating conditions on the tribological performance of the tribo-pairs were discussed.