SOLUTIONS FOR ENTERPRISES
MANUFACTURE OF STEEL-BRONZE PARTS
NTV Scientific & Technical Firm developed a technology for manufacturing bimetallic steel-and-bronze sliding bearings (cylindrical and tapered liners, ball sockets, thrust bearings, working cylinders, guides, etc.) instead of bronze casting.
The experience of using parts made according to our technology allows us to speak about a significant increase in the durability of their work compared to bronze castings*.
The manufacturing technology of bimetallic parts consists in depositing of the BrOF 6.5-0.4 tin-phosphor bronze layer on a steel surface.
Low-carbon or medium-carbon steels St3, St20, St30, St35, St40, St45 are used for the manufacture of the workpiece.
Minimum thickness of the deposited layer of bronze is 3 mm, the maximum is 8 mm.
Depositing can be performed on the surface of any configuration and size, with the exception of holes with a diameter of less than 100 mm.
Typical chemical composition of deposited bronze: Sn 6.90-6.95 %; Р 0.76-1.08 %; Cu – the rest.
The structure of the deposited layer is shown in the figure and is an α-solution (microhardness H=1500-1600 MPa), eutectoid Cu31Sn8 and phosphide Cu3Р (microhardness H=2600 MPa), formed when the phosphorus content is more than 0.3%. It improves casting properties, increases hardness, strength, elastic and anti-friction properties. The change in the chemical composition of the material in the deposition process leads to the fact that it is close in properties to the BrOF 10-1 bronze.
Results of comparative tests on wear resistance, carried out using friction machine according to the "worn-out hole" method showed that the deposited bronze under conditions of moderate loads is comparable in wear resistance to the BrOTsS 5-5-5 bronze, however, a further increase in load leads to a sharp increase in the wear of the BrOTsS 5-5-5 bronze up to seizure, while the wear of the deposited bronze only slightly changes. During the tests, a significantly smaller effect of the mating steel surface roughness on the wear of the deposited bronze was noted.
* Dependence of wear of the deposited bronze BrOF 6.5-0.4 and Br OZS 5-5-5 on the load at different roughness of the steel surface