PM processing of high nitrogen stainless steels

PM processing of high nitrogen stainless steels

PM PROCESSING OF HIGH STAINLESS STEELS NITROGEN J.WSimmons et al. (Albany Research Center, USA) J. Metals, Vol 48, No 4, 1996, 2023. It is provides...

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PM PROCESSING OF HIGH STAINLESS STEELS

NITROGEN

J.WSimmons et al. (Albany Research Center, USA) J. Metals, Vol 48, No 4, 1996, 2023.

It is provides production any other cost, Two solid and made by nitriding machine.

reported that the use of PM a more satisfactory route to of high N stainless steel than method and at greatly reduced methods are described involving liquid state processing of powders pressurized gas atomization and in a mechanically fluidized

characteristics. It is shown that WC-Co performs well at low cutting speed but other cermets are better at higher speeds. It is reported that hard films, notably homogeneous Ti-N-C, have high reliability. Multilayer and graded coatings are no better for interupted cutting. MEASUREMENT OF COATING/ SUBSTRATE INTERFACE STRENGTH BY LASER INDUCED SPALLATION

CTang, J.Zhu (Xi’an Jiaotong University, Xi’an, Shaanxi, China.) Int. J. Refractory Metals Hard Mater., Vol 14, No l/3, 1996, 203-206.

A THERMOANALYTICAL. NITRIDING A HIGH

STUDY OF SPEED STEEL

O.A.Mazno et al. Poroshkovaya Metallurgiya, No 5/6, 1995, 21-24. (In Russian.) Nitriding of a steel powder in NH, was analyzed by thermogravimetry. Temperature limits for adsorption of N, nitriding and de-nitriding were determined. Conditions for nitriding a high speed steel with more than equilibrium concentrations of N are suggested.

Tungsten LOW TEMPERATURE CARBURIZATION OF TUNGSTEN POWDER WITH HIGH SURFACE AREA

L.Gao, B.H.Kear (Rutgers University, New Jersey, USA) Nanostruct. Mater., Vol 5., No 5, 1995, 555-569. It is reported that reduction of WOs above 650°C yields clW powder of high surface area. Below 575°C the product is PW and between the two a mixture of CI and PW is formed. Carburization in CO at 350 to 700°C is sensitive to the crystalline form of W. clW carburizes to WC and p W to WzC. An explanation is given.

SINTERING OF BASED POWDERS

ULTRAFINE

ZIRCONIA

Y.V.Dudnik et al. Poroshkovaya Metallurgiya, No 5/6, 1995, 43-49. (In Russian.) Effects of powder characteristics and process conditions on sintering of ultrafine ZrOz powder were investigated for a range of sintering processes.

on hardmetal

CUTTING PERFORMANCE MULTICOMPONENT AND COATINGS ON CEMENTED

too/s

OF MULTILAYER CARBIDES

OKnotek

(RWTH, Aachen, Germany.) Metals Hard Mater., Vol 14, No l/3, 1996, 195-202. Benefits of coatings of cermet tools are outlined with reference to durability and product quality. Performance is shown to depend on substrate and coating Int.

et al. J. Refractory

36

FRACTURE MEASUREMENT MAGNETRON

MECHANICS OF ADHESION OF SPUTTERED COATINGS

S.Berg et al. (Max-Planck Inst. for Materials Research, Stuttgart, Germany.) Int. J. Refractory Metals Hard Mater., Vol 14, No l/3, 1996, 207-211. Determinations of adhesive strength between TiN coatings and high speed steel substrates, by 3-point bend and modified shear tests are reported. S-point bend tests yield fracture mechanics data but requires a notch which initiates cracks at the interface. Sub-layers, with low adhesive strength, or thin slots, were used. The resaults are reported to indicate that substrate condition before coating deposition is the main strength controlling factor. Test methods are critically reviewed. NON-DESTRUCTIVE X-RAY METHODS FOR QUALITY CONTROL OF THIN CERAMIC COATINGS

Ceramics

Coatings

A study of coating/substrate interface strength, by laser spalling of the coating, is described. TIN coatings on pure Fe were studied. Spalling is considered firstly as break-up of the coating then detachment. Interface strength and strain rate are estimated.

MPR November

1996

S.Y.Bestofen (Russian Academy of Sciences, Moscow, Russia.) Int. J. Refractory Metals Hard Mater., Vol 14, No l/3, 1996, 213-221. Effects of macrostresses, textures and coating thickness on reliability of thin ceramic coatings are reviewed. It is shown that differences in thermal expansion determine the magnitude of residual macrostress. An X-ray technique has been developed for measurement of coating thickness. The accuracy is discussed for various coatings and substrates.

Composite

materials

ANISOTROPY OF THERMAL EXPANSION IN HOT PRESSED MOLYBDENUM-ZIRCONIA COMPOSITES

R.Watanabe et al. (Tohoku Sendai, Japan.) J. Japan Inst.

60, No 1, 1996, 50-55. (In Japanese.) MO-partially stabilized ZrOz composites were investigated for anisotropy of thermal expansion. It is assumed that the anisotropy is related to microstructural orientation arising from uniaxial hot pressing. It is shown that thermal expansion is greatest in the pressing direction and that the anisotropy depends on composition with maximum anisotropy at 60vol%ZrOz. The results are discussed with regard to Eshelby’s theory. HIGH TEMERATURE BETWEEN SILICON IRON-NICKEL ALLOY

REACTION NITRIDE POWDERS

AND

T.Shimoo et al. (Osaka Prefecture University, Sakai, Osaka, Japan.) J. Japan Inst. Metals, Japanese.)

Vol

60,

No

1,

1996,

Z-78.

(In

Reactions between SisN, and 469wt% Fe-Ni powders were investigated at 850 to 1300°C in N or Ar using thermogravimetry. There was greater weight loss in Ar. The reaction took 20 hours in Ar. The reaction kinetics are described with initially linear and then parabolic rate laws. Mechanisms considered are gaseous and solid state diffusion.

Electrical materials APPLICATION ALLOYING MATERIAL

and

magnetic

OF MECHANICAL TO THERMOELECTRIC IRON SILICIDE

M.Umemoto (Toyohashi University of Technology, Toyohashi, Japan.) J. Japan Sot. Powder Powder Metall., Vol 42, No 2, 1995, 135-140. (In Japanese.) It is reported that MA of Fe-66.7at%Si, doped with Mn and Al, enhanced thermoelectric properties. Optimum milling time was 200 hours, which gave very fine crystalline Fe and Si powder which was hot pressed. Structural evolution to FeSiz and properties are described. MECHANICAL ALLOYING OF THERMOELECTRIC BISMUTHANTIMONY THERMOELECTRIC MATERIAL

M.Miyajima et al. (Tohoku University, Sendai, Japan.) J. Japan Sot. Powder Powder Metall., Vol 42, No 2, 1995, 146. 150. (In Japanese.) Effects of MA on thermoelectric properties and structural evolution in Bi7.5at%Sb powders were investigated. MA powders were hot pressed giving a grain size of 1 pm. Grain size and electrical resistivity decreased with increased milling time. MECHANICAL GRINDING OF SAMARIUM-IRON-NITROGEN ALLOYS PROCESSING AND PROPERTIES

University, Vol

Metals,

M.Ito

et al.

(Osaka

University,

-

Osaka,