GB2528483A

GB2528483A - Sliding member

Info

Publication number: GB2528483A
Application number: GB1413060.3A
Authority: GB
Inventors: Maikihito Yasui; Hiroyuki Asakura; Shigeya Haneda
Original assignee: Daido Metal Co Ltd
Current assignee: Daido Metal Co Ltd
Priority date: 2012-01-18
Filing date: 2014-07-23
Publication date: 2016-01-27
Also published as: WO2013108741A1; DE202013012215U1; US20150291904A1; KR20140112518A; DE112013000605T5; JP2013148137A

Abstract

Provided is a sliding member which has high seizing resistance though an overlay layer comprising Ag as the main component is used therein. The sliding member of an embodiment comprises a base and an overlay layer which is disposed on the sliding-side surface of the base and which comprises Ag as the main component and contains Al. The overlay layer comprising Ag as the main component is relatively soft. Due to this, the overlay layer comprising Ag as the main component can ensure high seizing resistance even when the use of Pb is avoided. Furthermore, the overlay layer comprising Ag as the main component has excellent thermal conductivity. Due to this, frictional heat generating at the sliding part rapidly dissipates to the base side.

Description

I

DESCRIPTION

SLIDING MEMBER

TECHNICAL FIELD

[0001) The present invention relates to a sliding member.

BACKGROUND ART

[0002) Conventionally, a sliding member of a slide bearing for an internal-combustion engine etc. comprises an overlay layer on a sliding-side surface of a base such as a steel back plate. For such an overlay layer, there is proposed an overlay layer which comprises Ag as a main component and to which In,, Sn, Bi, or the like is added, in order to obtain sliding characteristics to the same degree as those of a sliding member containing Pb, while avoiding the use of Pb (Patent Literature 1).

[0003J Howeveç although In, Sn, and Ri are softer than Ag, their thermal conductivities arc extremely smaller than that of Ag. Therefore, an overlay layer which comprises Ag as a main component and to which In, Sn, or Ri is added cannot easily dissipate the heat generated in the sliding part with a mating member, to the base side. As a result, the temperature of an overlay la*r of this type easily rises under severer conditions, causing reduction in strength and hardness, which causes a problem of easily resulting in seizure.

CITATiON LIST

PATENT LITERATURE 004]

PATENT LITERATURE 1: JP-A-11 -257:355

SUMMARY OP iNVENTION

TECHNiCAL PROBLEM ¶0005) Thercfore, an object of the present invention is to ptovi4e ti sIidizg member 0 having igh &lzure reStance even when an Ag-based overlay layer is med.

SOLUTION Ii) P1(0131 EM [00061 The sliding member according to chum I comprises: a base and an Ag-based overlay layer disposed on a sliding-side surface of the base and comprising AL Moreover. the sliding member according to claim 2 comprises: a base: and an Ag-based overlay layer disposed on a sLiding-side surface of the base and comprising Al, the overlay layer further comprising ai least one of Sn and Zn.

The Ag-based overlay layer is relatively soft, Therefore,the Ag-based overlay layer can ensure high seizure resistance even when the use ofPb is avoided. Moreover, the overlay layer comprising Ag has excellent thermal conductivity. Thercforc, the frictional heat generated at a sliding part is rapidly dissipated to the base side. The present inventors have found that the addition of Al to an Ag-based overlay layer does not cause significant reduction in the thermal conductivity of the overlay layer. That is, the addition of In, Sn, Di. or the like to an Ag-based overlay layer has been known as a prior art. However, in, Sn, and Hi as additive elements have small thermal conductivity, and they have a problem of disturbing rapid dissipation to the base side of the heat generated in the sliding part with a mating member. On the other hand, Al in the present invention has a relatively large thermal conductivity and facilitates the function of an Ag-based overlay layer, that is. rapid heat dissipation to the base side by the high thermal conductivity. Therefore, the sliding member of the present invention can achieve high seizure resistance even when an Ag-based overlay layer is used, and it can endure even in the use under severer conditions.

Moreover. the.: Ag_,basc:d irs.' ran' Layer t. ftf rtst irtvcntton reivy ciraprise riot.

enie Al hcai: aso at r.t*--of.tii ani.i La a ifl iTi:dCfiti'VC, tt)'. :>,, nc-ok the p crer.tt nivt'e1ion a: Id tha an.A:rLDeisedovcriav er c:omprisirig / *;pJ ie.refore, fç rcsc'ra invennon does nor & iImintte that ann ddOIvt cit ureili ottrer than Al and nun voidable rnpunncs. arc contained in the overlay lace.

[0009] hl the sliding member according to claim 3. the overlay layer comprises 0. 1% by mass to 1 3% by mass cFt\ In the Ag-based overlay brer the orig! nal thermal conductivi r y of Ag is exhibited as the proportion Ag intteeses, and the heat dissipation roan the o yc.Irbhv to the *hase. sjde is theilitated. On the orhot i:and.. as the rovorton üí \1 itt me overlay layer increases, the thermal conductivity of the overlay layer comes close to the thennal conductivity of Al from the original thennal conductivity of Ag. Thus, in the present invention, when adding Al to an overlay layer; the upper limit of Al is 15% by mass.

S BRIEF DESCRIPTiON OF DRAWiNGS

[0010] [Fig. 1) Fig. I is a schematic sectional view of a sliding member according to an embodiment.

IFig. 2] Fig. 2 is a schematic view showing the test results of a sliding member according to an embodiment.

(Fig. 3] Fig. 3 is a schematic view showing the conditions of the seizure resistance test of a sliding member according to an embodiment.

[Fig. 4J Fig. 4 is a schematic view showing a sample used for the seizure resistance test of a sliding member according to an embodiment.

DESCRIPTION OF EMBODIMENTS

[00111 Hereinafter, a specific embodiment of a sliding member will be described.

First, the procedures for producing a sliding member to be used as a sample in the present embodiment wilt be described.

As shown in Fig. 1, a sliding member 10 comprises a base 11 and an overlay layer 12. The base II has a back plate layer 13 and a Cu-based or Al-based bearing alloy layer 14.

The back plate layer 13 is formed from steel. Thus, the base 11 is a so-called bimetal comprising the steel back plate layer 13 and the Cu-based or Al-based bearing alloy layer 14.

The base Ii formed from the back plate layer 13 and the bearing alloy layer 14 is shaped into a seScylüidrica! 01 cyfindrica! shape The suzrmace of the shaped base I on the side of the hearing at toy layer 34 is sukjccted to surtäce maehiidng such as boring. The wiace oi the base ii subjected to surfacc machining is washed by eectrotylk Sgre'zsing and 4 ith acid. Thus, after the surface of the base it i washed, an Ag-based oveitay layer 12 made of an Ag-At alloy is fomte4 thereon by sputtering or the like. Further, instead of sputtering, the overlay layer 12 can also be formed by plating Ag on a layer made of Al and by forming an Ag-At ahoy comprising Ag as a main component utilizing diffusion. in this case, the diffusing capacity and distribution of Al in the overlay tayer 12 can be controlled by temperature arid time. Moreover.

one or two or note intermediate, layers (not shown) may be disposed between the base 11 and the overlay layers 12.

[0012J In the present embodiment the overlay layer 12 is formed by sputtering using a magnetron sputtering system (not shown). A specific example for forming the overlay layer 12 will be described using the sliding member 10 of sample 1, which is an Example shown in Fig. 2.

s In the case of sample 1, a base 11 after washing consisting of bimetal is mounted on a base mounting pan of a magnetron sputtering system. Moreover, Ag and Al serving as the materials for the overlay layer 12 are mounted on a target mounting part of the magnetron sputtering system as targets.

Afler the base 11 and Ag and Al which are the targets are mounted, the chamber of the magnetron sputtering system is decompressed to 1.0 x io Ton and adjusted to 2.0 x 10-' Ton' by supplying Ar gas. After the pressure of the chamber is adjusted, the surface of the base ills cleaned with Ar gas. In this case, a bias voltage of 1000 V is applied to the surface of the base II. This produces Ar plasma between the base 11 and Ag and Al serving as targets, and reverse sputtering is performed for 15 minutes. Alter the cleaning with Ar plasma is performed, voltage is applied to each target so that a current of 8 A to 14 A may flow into Ag as a target and a current of 0.5 A to 6 A may flow into Al as a target At this time, the bias voltage between the base 11 and the targets is set between 100 V and 200 V. According to these procedures, Ag and Al serving as targets are sputtered by the collision of Ar ions and form a film on the surface on the side of the bearing alloy layer 14 of the base II.

(0014] When a produced sample corresponding to sample I was subjected to ERMA (Electron Probe Micro Analysis), it was verified that Al was unifonnly dispersed in the overlay layer 12 with Ag being used as a matrix. The amount of Al added to the Ag-based overlay layer 22. 12 cnn be contwlled by sdjusiing the moss raclo of Ag and Al to be mounted on a target rric9znung part as the varets of sputterhg and the enmuu to be passed through the Ag and M scrvin a; target's.

Sliding members 10 of samples I to 16 corresponding to Examples. ased s1idng members tO of samples 11 to 21) corresponding to Comparative Examples as shown in Fig. 2 were formed according to the above procedures.

(00151 (Seizure resistance testj The re4ultirtg siktiiig rnemben 10 of samples Ito!6 as Examples and sarnpes 17 to 20 as Comparative Extnpcs were verifle4 fnr seinrc esiswnce by a shim biting test.

The test conditions of the shim biting test are shown in Fig.. 3. in the shim biting mci, a lest sample is prepared by attaching a metal shini 15 having a sL..e of 2 rum x 2 mm X t to the outer circumferential surface of each of the sliding members 10 of samples i to 16 as Examples arid samples 17 to 20 as Comparative Examples, as shown in Fig. 4. in the test, the 6 thickness of the shim 15 is set to 10 urn. The thickness i. of the shim 5 can he set from about jim to 30 jim depending on the conditions ol the test. The test sample of the sliding member lOis installed in a roratioral load tester which is a seizure tester (riot shown). The shim 15 is attached to the test sample of the sliding member tO. Thus. when the test sample of the sliding member lOis installed in the seizure tester, a portion corresponding to the shim IS on the test sample of the sliding member 10 projects to the inner circumferential side depending on the thickness of the shim 15. This projected portion generates heat by contacting with the test shaft of the seizure tester. Therefore, the amount of heat generated by the contact of the test sample of the sliding member 10 with the test shaft is increased by increasing the load applied to the test sample of the sliding member 10 in contact with the test shaft. As a result, the lower the thermal conductivity of the overlay layer 12 in the test sample of the sliding member 10 is, the more easily seizure will be occurred ott the overlay layer 12 at an early stage. In the test in the present embodiment, the load applied to the test sample of the sliding member LOis increased by MPa every 10 minutes. Then, when the back temperature of the test sample of the sliding member 10 exceeds 200°C. or when a slide occurs in a shaft drive belt of the seizure tester by the variation of torque applied to the seizure tester, it is determined that seizure has been occurred in the test sample of the sliding member 10.

110016] Hereinafter, concerning the seizure resistance, verification results will he exammed based on Fig. 2 from the vie'..vpoimn 01 the maximum srfrceific.k'ud without seizure APa).

zt:)tesi to: 6 are Enrnples Li wa ich A I is taklc:d tO tOO AfbttSe.ti (}"eIjaV la)!er 2.. The ti)i/ are mSL:tattces or triese hxaThpits have rnp:ro cii 35 c0.tLtliareti Wid S.zl.HiP;C.**. I (ins Contparative Examples. 1hat is2 samples i 16 as Examples have better seizure resistance by adding Al to the Ag-based overlay layer 12 than sampie. 17 in which the overlay layer 12 comprises only Ag. This is probably because eonThrmability is improved by adding Al that is softer than Ag. thereby improving seizure resistance. Shuilarly, samples 1 t.o IC' as Examples base better se r.f1rU than sample i 8 in whteh Sn is added to the Ag..base:d ov ethy in ed, 2. a dt.h.our addirty Al. sample 1 9.iit teiiic:h iz s adda3 si.mii.ady, and saint 9 20 in whkh 131 is added similarly. flit sth,ntr mcd tanees of rpnis 1. to 1 6 heeL' been ruimove d probably because the thermal conductivity of the overlay layer thereof is lager than that of samples 18, 19, and 20.

[001:i On the other hand, although the seizure resistances of samples 15 and 16 as Exan.iples are higher than that of sample 17 as a Comparative Example, it is lower than that of sample 14 as an Example. This shows that, in the Ag-based overlay layer 12, an increase in the amount of Al added tends to reduce the seizure resistance. That is, when the amount oVAl added to the Ag-based overlay layer 12 becomes excessive, the thermal conductivity of the overlay layer 12 will be closer to that ofAl than Ag. Therefore, it is considered that samples 15 and 16 in which the amount of Al added is high have lower seizure resistance than sample 14.

Consequently, it has been found that the addition of Al to the overlay layer 12 achieves improvement iii seizure resistance, and the addition of a predetermined amount of Al contributes to the exertion of excellent seizure resistance.

10018] Moreover, the seizure resistance of sampleS as an Example is better than that of sample 4. and the seizure resistance of sample 8 is better than that of sample 9. Similarly, the seizure resistance of sample 11 is better than that of samples 12 and 13. This shows that. in the ease of the Ag-based overlay layer 12 comprising Al. when the content of Al is approximately the same. the seizure resistance can be more improved by not adding Sn, Cu. Zn, or 13i. l'hat is, when an element having a smaller thermal conductivity than Al is added to the Ag-based overlay layer 12. the thermal conductivity of the overlay layer 12 will he smallerthan the case where only Al is added. Therefore, it is considered that samples 4,9, 12. and 13 in which an element other than Al is added to the overlay layer 12 have a lower seizure resistance than a sample in whic.h substantially cmlv A is added and the content of A in the overlay layer 12. is about the C..ense:tuenfl y. it. has been fctmd that aitl.iough sclswe csytacoc an be ensta xl even an cse meet other Jun A] is added to dx y]?Y aver 2. he addition of an elerner) I oilier that; Al ts nor ad -*-otaneous So seizwc res.tst rice, Moreover, it. has been found that, based on samples I to 16 as Exampkc. the presence or ahserice of an intermediate layerc the type of an inlermediate layer. arid the type of the bearing alloy layer 14 have only a small influence on se zure resistance. Furthermore, aithrnigh not patticulad shown, it has bee ii found that even if Al is added) the Ac based overlay Layer 12.? and. I adeijEjon. hard particles and rnetai clot its ialber than those shown in Esarup ICS' m_.adtlcei thereto, a hiitfter su-.-" c;oinre than that ot ovcrto layer 12 comprising only Ag can be achieved. Consequently, if Al is added to the Ag-based overlay layer 12, an improvement in seizure resistance can be achieved regardless of the presence or absence of other additive components or the type of additive components, as long as the amount ofAl added is not excessive.

t00201 Moreover, in the sliding member 10, other layers such as a conformable layer may further be disposed on the sliding-side surface of the Ag-based overlay layer 12. A further layer such as a conformable layer is preferably a layer comprising, for example. 131 or a Si alloy.

Although not particularly shown, a sliding member of an embodiment in which a confonnable layer is disposed also has excellent seizure resistance and, in particular, had excellent initial conformability. Thus, the sliding member 10 of an embodiment in which a conformable layer is disposed was naturally able to exhibit high seizure resistance even if the conformable layer was worn out to expose the Ag-based overlay layer 12.

[0021) The present invention as described above is not limited to the above embodiments and can be applied to various embodiments without departing from the scope of the present invention.

REFERENCE SIGNS LIST

[0022] Sliding member 11 Base 12 Overlay layer 13 Back plate layer 2 14 Bearing alloy layer