JPS6111308B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to iron-brass-based and iron-bronze-based sintered alloys that, when used as sliding members, cause less wear on themselves and on mating members than conventional materials. In general, iron-copper based sintered oil-impregnated alloys are attractive in that they are cheaper than copper-tin based alloys, but their drawback is that they tend to wear out mating parts. Therefore, iron modified by adding zinc or tin.
Brass-based and iron-bronze-based materials have been used, as well as materials that have been made self-lubricating by the addition of small amounts of lead or graphite. However, in many cases it is still unsatisfactory depending on the application, and improvements have been desired. In response to this, the inventors conducted various research and found that
It has been found that adding a small amount of boron significantly improves the sliding properties. That is, the gist of the present invention is to add 0.03 to 1% boron to each of the above materials. The present invention will be described in detail below based on experimental results including Examples and Comparative Examples. Experiment 1, which will be described next, concerns an iron-brass system, and Experiment 2, which will be described later, concerns an iron-bronze system. Experiment 1 〓〓〓〓〓
This is a typical composition of iron-brass sintered sliding materials.
Based on Fe-15Cu-10Zn, we decided to mix copper and zinc in the form of brass alloy powder. First, the particle size is less than 200 mesh and the zinc content is 40.
% brass powder, add 25% of this alloy powder to atomized iron powder of 100 mesh or less, and 0.3% as a lubricant.
After adding % zinc stearate and mixing thoroughly,
Green density 6.1 with inner diameter 12.5mm, outer diameter 16mm, length 12mm
g/cm ³ and sintered at 850° C. for 20 minutes in a decomposed ammonia atmosphere. After sintering, sizing and impregnation with No. 2 turbine oil were performed, and this was designated as Sample 1. Next, Fe-20B alloy powder with a grain size of 200 mesh or less was prepared for boron addition, and 0.75% of it was added to the raw material powder of Sample 1, and the steps after molding were the same as Sample 1 to create Sample 2. . The boron content of this sample 2 is 0.15%. In addition, sample 3 with 1% lead added to the composition of sample 1
Sample 4, which had the composition of Sample 2 with 1% lead added, was prepared in the same manner. The component compositions of these samples are shown in Table 1. Sample 2 and sample 4 containing boron
corresponds to an example of the present invention and does not contain boron 1
and 3 are comparative examples.

[Table] Next, each sample was placed in a bearing testing machine, and the S45C annealed material was rotated continuously at a load of 9 kg/cm ² and peripheral speed of 120 m/min using the S45C annealed material as the shaft, and the amount of wear on the shaft and bearing was measured at predetermined intervals. did. The results are shown in FIGS. 1 and 2. First of all,
Looking at Figure 1 regarding shaft wear, which is the most important issue, there is no difference between the samples until 20 hours after the start of the test, but for sample 1, which has the basic composition, the amount of shaft wear increases significantly after 50 hours. However, sample 2 with lead added was also
After 100 hours, it shows an increasing trend. On the other hand, in the case of Samples 3 and 4 according to the present invention, the wear of the shaft was small even after 100 hours, and in particular, in Sample 4, the synergistic effect of boron and lead was clearly manifested. Next, looking at the wear of the bearing (sample itself) in Figure 2, sample 1 showed quite large initial wear, then stabilized for a while, and then increased again after 100 hours. In addition, sample 2 with lead added had less initial wear, but like sample 1, the wear increased significantly after 100 hours. On the other hand, Samples 3 and 4 according to the present invention remained stable even after 100 hours, and especially Sample 4, which used both boron and lead, had a significantly low level of wear and A clear significant difference is observed. Experiment 2 Typical composition of iron-bronze sintered sliding parts
Based on Fe-22.5Cu-2.5Sn, we decided to mix copper and tin in the form of bronze alloy powder. First, the particle size is 200 mesh or less and the tin content is 10
% bronze powder, add 25% of this alloy powder to atomized iron powder of 100 mesh or less, and 0.3% as a lubricant.
% of zinc stearate was mixed and formed into a bearing having the same shape as in Experiment 1, it was sintered at 830°C for 20 minutes in a decomposed ammonia atmosphere. After sintering, the same treatment as in Experiment 1 was performed, and this was designated as Sample 5. Next, 0.75% of Fe-20B alloy powder was added to the raw material powder of sample 5, and the steps after molding were the same as sample 5.
Sample 6 was produced. The boron content of this sample 6 is
It is 0.15%. In addition, sample 7 has the composition of sample 5 with 2% graphite added.
Sample 8, in which 2% graphite was added to the composition of sample 6, was prepared in the same manner. The component compositions of these samples are shown in Table 2. Sample 6 and sample 8 containing boron
corresponds to an example of the present invention and does not contain boron 5
and 7 are comparative examples.

[Table] Next, for each sample, do the same as in Experiment 1.
A wear test was conducted. The results are shown in Figures 3 and 4.
Compared to the iron-brass system, there was less wear overall and the stable wear region was slightly longer, but the trends among the samples were almost the same as in Experiment 1. That is, in this system as well, the addition of boron has a remarkable effect on reducing wear of both the shaft and the bearing. The reasons why the wear resistance is improved by the addition of boron are that the Fe-B alloy phase, which is harder than the base, is dispersed in the base and improves its own wear resistance. Boron nitride is generated by reaction with nitrogen in the atmosphere, and it is thought that this improves compatibility and reduces wear on the other side, but the details are unknown. Incidentally, BN was detected in the structure sintered in an atmosphere containing nitrogen, and when this was subjected to a sliding test, results were obtained that the temperature rise due to friction was small. The lower limit of the amount of boron added at which such an effect can be clearly observed is 0.03%; on the other hand, if it exceeds 1%, the material becomes excessively hardened and wear on the other side increases again. For these reasons, the amount of boron added should be 0.03~
1%. Although pure metal powder may be added, it is preferable to add it in the form of alloy powder with iron or copper in order to uniformly mix a small amount. Although it is possible to use a single metal powder for the blending of copper, zinc, tin, etc., it is preferable to add an alloy powder that ensures uniform mixing and a desired structure. The alloy composition in the present invention is brass powder containing 10 to 40% zinc and 2% tin.
It is a well-known fact that 10 to 60% of alloy powder, such as ~10% bronze powder, is mixed with iron powder, which is usually commercially available. As described above, according to the present invention, iron-brass sliding materials and iron-bronze sliding materials have the advantage of being cheaper than copper-based sliding materials, while also causing less wear on themselves and mating members compared to conventional sliding materials. A sliding material of
Its scope of application has been expanded in terms of both price and performance.

[Brief explanation of the drawing]

Figures 1 and 2 are graphs showing the effects of adding boron and lead to the base material on the wear resistance of shafts and bearings when iron-brass sintered alloys are used for bearings, Figures 3 and 4 is also a graph showing the influence of boron and graphite on the iron-bronze sintered alloy. 〓〓〓〓〓

Claims (1)

[Claims] 1. A sintered alloy for sliding members characterized by the following composition in terms of weight ratio: Cu...6 to 54%, Zn...1 to 24%, B...0.03 to 1%, Fe...the balance. 2. A sintered alloy for sliding members characterized by the following composition in terms of weight ratio: Cu...6 to 54%, Zn...1 to 24%, at least one of C and Pb...4% or less, B...0.03 to 1%, Fe...the remainder. 3. A sintered alloy for sliding members characterized by the following composition in terms of weight ratio: Cu...9 to 60%, Sn...0.2 to 6%, B...0.03 to 1%, Fe...the balance. 4. A sintered alloy for sliding members characterized by the following composition in terms of weight ratio: Cu...9 to 60%, Sn...0.2 to 6%, at least one of C and Pb...4% or less, B...0.03 to 1%, Fe...the remainder. 5. It is characterized by adding 0.03 to 1% by weight of boron to the raw material powder of iron-brass alloy or iron-bronze alloy, forming it into the desired shape, and sintering it in an atmosphere containing nitrogen. A method for manufacturing a sintered alloy for sliding members.