Tribological properties of ceramic and metallic composite coatings

Tribological properties of ceramic and metallic composite coatings

Conference Io Powder 2000 It was noted that PM parts may be damaged Metallurgy World Congress, held in Kyoto, Japan, in November during For fur- ...

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Conference Io Powder

2000

It was noted that PM parts may be damaged

Metallurgy World Congress, held in Kyoto, Japan, in November

during

For fur-

2000.

Bldg, 2-16, Iwamoto-cho

2-chome,

ing. Variations emphasis

(N&d

was reported

Tsing-Hua

T.Watmabe

that

Mn-Zn

by longitudinal

and Ni-Zn

microwave processes. Sintering

behaviour

was

investigated

material

and

with

regard

variables

to

and

process

control.

between Mn-Zn and Ni-Zn ferrites were outlined.

bronze

of

was presented.

This

theories

approach. tionally

a new

The

fracture

depends

theory

on new

and was developed analysis

and

an

and from

energy

The new theory was applied addito other

associated

fracture

with fracture,

mode II and mixed

criteria.

Problems

including

mode

modes of fracture

considered.

Singular defects affecting fatigue of PM materials B.Weiss,

(University

H.Danninger.

of Technology,

Vienna, Austria.) The

sensitivity

was noted. shown

of PM materials

Defects

that

were

the

to defects

identified.

effects

of

It was singular

defects can be described by a Kitagawa diagram based on fatigue intensity that realistic

factor.

limit

and threshold was

It

predictions

stress

suggested

are only possible

stress fields round defects and interactions adjacent defects are taken into account.

www.metal-powder.net

modulus

were

et

al.

(University

of Technology,

Dresden,

if

with

were characterized ness. Al,Ni,

pow-

alloyed in Ar. Powders

for size, structure and hard-

AlNi,,

and traces of Al,Ni,

and

A13Zr were detected. Milling reduced crystallite size to 10 nm. The structure was stable on heating with further synthesis of Al,Ni,.

Structural evolution in aluminiumiron-chromium powders during high energy milling (Toyama University, Japan.)

were mechanically weight

ratio

at a ball:powder

of 238:lO.The

were characterized to determine cx Al(Fe,Cr)

25. 35 or SO)%Fe

alloyed

milled

powders

for structure and properties

the effects of the Cr addition. and CI Fe(Cr)

solid solutions were

formed initially with intermetallic

compounds

M.Mihad

et

al.

of Cmioua, Craiova,

(University

RomLmia.) importance and

of detecting

variations

inhomogeneities

in

in

injection

It was reported powders,

with

that superconducting A15

structures

alloy

had

been

moulded brown parts and the need for repro-

formed by mechanical

ducibility were emphasized. Defects may not be

and Si powders. The powders were evaluated

detected before production

for effects of process parameters.

of parts has started,

which may lead to disruption Microtomography destructive

of production.

was identified

technique

for detection

alloying of Nb, V, B, Al

peratures for superconductivity

Critical

tem-

were measured.

as a nonof density

was discussed.

Friction and porous materials

Mechanical alloying

Effects of admixed solid lubricants on dry sliding behaviour of sintered steels

variations.

Optimization

of process parameters

I,

were

alloying. Al-8%Ni-l.S%Zr-O.S%Mn-O-C der was mechanically

was

Structures of Al5 intermetallic compounds formed by mechanical alloying

density

(PO Box 1770, Cairo, Egypt.)

on Young’s

regard to use of mechanical

with

phases,

Study of three-dimensional density distribution in injection moulded ‘brown’ parts

Composites and new concepts of fracture Application

materials

of Fe base and

alloys,

discussed

Ternary Al-Sat%Cr-(10,

Effects of materi-

Al

of intermetallic

Z.Yong etal.

of Young’s modulus of sin-

and density

in strengthening

by formation

later and finally the powders were amorphized.

LJ.Btrth

experimental

and

of Ni

World Congress and

discussed.

Gemmy.)

updated

content

University, Japan.)

oscillations.

al composition

Testing and evaluation

R.El-Sheikhy.

with

tered materials were made using dynamic tests

University,

and

and applications

of porosity

et al. (Was&

Measurements

ferrites had been sintered by conventional

Differences

and density were

Young’s modulus of sintered materials

Taiwan.)

process

were

during tensile test-

in elasticity

on effects

is

matrix microstructure.

Co-sintering of manganese-zinc and nickel-zinc ferrites

It

this

measured at different plastic deformations

Sintering

al.

and that

defects. Concepts

of damage mechanics

used to study deformation

Japan;

fax: +81-(o)3-5687-0599.

et

loading

and methodologies

tel: +81-(0)3-3862-6646;

C.Y.Tstiy

mechanical

associated with pre-existing

ther details contact the JPMA: Tamagawa Chiyoda-ku, Tokyo 101-0032,

Effects

Damage evolution in PM alloys under tensile loading

PM 2000. The following Abstracts are of papers presented at the

Featuring selected abstracts from the PM2000

Fabrication of iron-silver laminated nitride materials

H.Danninger

M.Nagae

the

et al (Okayam

Laminated

University,

Okuyama, Japan.)

Fe-Ag nitride material was made

by nitriding

rolled foil, stacking and re-rolling

repeatedly.

Structures

and

electro-magnetic

properties were measured and the results were discussed.

Synthesis of aluminium alloy base nano-composite by mechanical alloying T.Raghu

et al.

Hydembad,

In&.)

(Defence

Metdurgical

Research Lab,

et al. (University

of Technology, Vienna,

AUStliLZ.)

Dry pin-on-disc effects

tests were used to evaluate

of solid

lubricants

incorporated

into sintered

steels. Pb and various sulphides

were

but

added

Reduced

sulphides

into

decompose

FeS

coefficient

were

during

of friction

shown

to

sintering. was rare and

was linked

to high wear rates in dry tests.

Mechanisms

for the wear rates were described.

Tribological properties of ceramic and metallic composite coatings R.G&w,

D.Scherer.

(University

of Stuttgart,

Stuttgmt,

Germany.)

MPR November 2001

41

It was noted that reduced use of lubricants and use of lightweight materials, such as Mg alloys, were current engineering issues. Use of coatings to reduce wear and friction was discussed. Such coatings could be hardmetal or ceramic primary layers with a polymer/solid lubricant or MoS, as a working surface. Such coatings were reported to have good tribological properties.

New sintered composite materials with improved wear resistance et al. (Ames SA, Barcelona, Spain.)

C.Molins

Investigations of metal matrix composite materials, with solid lubricants incorporated, made by PM techniques, were described. These were reported to have high wear resistance in applications with low or no lubrication. Results of tribological tests were presented with case studies of applications. It was shown that it may be possible to substitute these materials for ball bearings.

Tribological properties of titanium nitride films with implanted halogen ions A.Mitsuo,

T.Aizawa.

(Uniuersity

of Tokyo,

Tokyo,

) The effects of F and Cl, ion-implanted into XN films on high speed steel substrates, on tribological properties against steel counter-bodies, was investigated by pin-on-disc tests. There was no adhesion of material from the counterbody to the implanted films. Cl reduced the coefficient of friction and the amount of wear debris. F did not influence the coefficient of friction. The differences were attributed to differences in interaction of halogens with the counter-materials.

Effects of density, warm compaction, ejection cracks and shot-peening on fatigue of steels A.Bergmmk.

(Lund University,

Sweden.)

High cycle tests were carried out to determine the effects of %Cu (0 or 2%), %C(O.2 or 0.8) and density (7.lor 7.4 g.cmF3) of selected steels. In some double pressed/sintered samples there were ejection cracks and resulting low endurance. Changes were made to tooling and warm compaction was used. Shot peening was shown to aid in healing ejection cracks in sintered specimens but did not increase endurance.

Comparison of rotating bend and tensile fatigue tests MSato

et al. (Kobe

Steel Co, Ltd, Japan.)

Methods for fatigue testing were reviewed. Rotating bend, tensile and tensile/compression tests were compared using carburized low alloy steel as the test material. Results for each type of test were correlated with the steel and compared.

Fracture toughness of sintered pm-alloyed steel compacts using small punch tests

outside layers and the core, which imposes a compressive stress in the outer layers increasing strength and toughness. Self propagating high temperature synthesis and pseudo-HIP were used to fabricate Ti-B-Ni and X-BN-Ni systems which were evaluated.

Development of recycling for tungsten carbide-cobalt hardmetals K.Kanu&,

M.Nakmnura.

(IwateUniversity,

Japan.)

Recycling of W and Co in hardmetals was discussed with regard to cost of W and Co. A new method, involving treatment of the hardmetal with molten Sn, was described. Sn forms a brittle intermetallic compound with Co. The material is subsequently treated chemically and mechanically to yield 6O%WC with a particle size of 1 to 5 pm.

Recycling of scrap hardmetal M.Tasic et al. (Scientific Research Centre, Yugoslavia.)

Investigations aimed at recycling scrap WCCo powders were described. The powders were heated at 700 to 900 “C. WO was recovered by chemical means and reduced to W in H at 900 “C in presence of Pd as catalyst. The W powders were characterized for composition and morphology.

Japan.

Performance of sintered bearings at high and low speeds

R.Watmabe

T.Yam.se, M.Miyaska

(Hitachi Powders Metals Co Ltd,

) The performance of oil-impregnated sintered bearings, operating under boundary film lubrication, was investigated at low and high speeds. Good performance requires the material to have high wear resistance and high oil film strength. A range of materials was studied. The best performance was given by a sintered Cu-C steel with a hydrocarbon wax lubricant.

Strength and toughness Quantitative analysis of fatigue properties of PM material

Sendai, Japan.)

Mechanical properties of sintered manganesechromium-vanadiummolybdenum steels A.S&ketal.

lapan,

et al. (Tohoku University,

Strength and fracture toughness of 4 Ni-Mo steels were investigated with reference to density, composition and structure using a small punch test. Samples were spark plasma sintered. Strength and Jj, fracture toughness were determined from the load/displacement curve and showed clear dependencies on density and composition. Effects of microstructure were discussed.

(SlwakAcademyofSciences,

K&e,

SM.)

The low cost and high affinity for 0 of alloy elements Mn and Cr, used in steels, were noted. Mechanical properties of steels with 1 to 3%Mn and up to 0.25%C were evaluated. Samples were die pressed at 600 MPa, and sintered at 1120 “C for 1 hour in cracked NH,. The relationship between %Mn and properties was evaluated. Tensile strength up to 925 MPa was attained.

Symmetrical compositionally graded materials ofScience and

Technolog), Beijing,

Y.Serio et al. (Toyota Motor Carp, Japan.)

China.)

The need for further investigation of fatigue in high strength steels was discussed. An analy sis of the effects of defects in PM materials on fatigue nronerties was uresented.

Structural symmetrical compositionally graded materials were discussed with regard to means of production. These were made with differing thermal expansions between two

v

42

L

I

L

MPR November

2001

S.Rossi et al. (University

ofTrento,Trento,

Italy.)

Corrosion and protection of steel PM parts was discussed with reference to the methods used. Electrodeposition of Zn was shown to be effective but costly and a study of hot dip galvanizing was described. Hot dip galvanized parts were characterized for structure and corrosion resistance as functions of composition, density and part shape.

Dimensional control of copper-carbon steel parts H.Ishikaw

et al. (Kawasaki Steel Carp, Japan.)

Dimensional accuracy and retention of part shape of PM Cu-C steels were discussed with regard to difficulties in attaining these aims. A study to clarify the factors influencing dimensions and minimizing variations between parts, by application of segregation-free technology and quality management of powders, was described.

Environmentally friendly steel sintering technology

Quality

W.P.Shen. (University

Hotdip galvanizing of PM parts for corrosion protection

D.Geldner,

D.Warga.

(Mahlm Indumieofenbau

GmbH,

Germany.)

Measures for environmentally friendly sintering were described. Heat for dewaxing was generated by after-burning protective atmospheres and evolved waxes. Use was made of recuperative gas burners to reduce energy consumption. There was a significant reduction in energy usage.

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