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Online since: November 2011
Authors: Yong Jun Zhang, Jie Min He, Li Yun Zhu, Hui Jin, Jia Li
Considerable attention has also been focused on the incidence of a number of non-infectious diseases common in civilized societies, such as coronary heart disease, which could be attributed to a low DF intake.
[3] McKeown NM, Yoshida M, Shea MK, et al.: Whole-grain intake and cereal fiber are associated with lower abdominal adiposity in older adults, J Nutr.139 (2009) 1950-1955
[4] Qi L, van Dam RM, Liu S, Franz M, Mantzoros C, Hu FB.Whole-grain, bran, and cereal fiber intakes and markers of systemic inflammation in diabetes women, Diab Care. 29 (2006) 207-211
[6] Bazzano LA, Song Y, Bubes V, et al.: Dietary intake of whole and refined grain breakfast ceral and weight gain in men, Obes Res. 13 (2005)1952-1960
[3] McKeown NM, Yoshida M, Shea MK, et al.: Whole-grain intake and cereal fiber are associated with lower abdominal adiposity in older adults, J Nutr.139 (2009) 1950-1955
[4] Qi L, van Dam RM, Liu S, Franz M, Mantzoros C, Hu FB.Whole-grain, bran, and cereal fiber intakes and markers of systemic inflammation in diabetes women, Diab Care. 29 (2006) 207-211
[6] Bazzano LA, Song Y, Bubes V, et al.: Dietary intake of whole and refined grain breakfast ceral and weight gain in men, Obes Res. 13 (2005)1952-1960
Online since: September 2013
Authors: Y.B. Tian, H. Xu
In the grinding of brittle materials, it is well documented that grinding can occur in the ductile regime if the maximum depth of cut of individual abrasive grains is less than the critical depth of penetration that causes brittle fracture in a material.
The maximum undeformed chip thickness (hmax) represents the maximum depth of penetration of the active abrasive grains into the workpiece in the grinding event. hmax is determined by the bonding material, the depth of cut, wheel velocity, workpiece speed and the cutting tool geometry, can be calculated by [7-8]: (5) where E1 is the elasticity modulus of the grinding wheel; E2 is the modulus of elasticity of the workpiece; r is the chip width-to-thickness ratio (it was suggested that the range of r is 10-20); C is the grain surface density which is usually defined as the number of active points per area of the grinding wheel surface; Vw is workpiece feed rate; Vs is wheel speed; ae is the depth of cut; and deq is the equivalent wheel diameter.
The maximum undeformed chip thickness (hmax) represents the maximum depth of penetration of the active abrasive grains into the workpiece in the grinding event. hmax is determined by the bonding material, the depth of cut, wheel velocity, workpiece speed and the cutting tool geometry, can be calculated by [7-8]: (5) where E1 is the elasticity modulus of the grinding wheel; E2 is the modulus of elasticity of the workpiece; r is the chip width-to-thickness ratio (it was suggested that the range of r is 10-20); C is the grain surface density which is usually defined as the number of active points per area of the grinding wheel surface; Vw is workpiece feed rate; Vs is wheel speed; ae is the depth of cut; and deq is the equivalent wheel diameter.
Online since: September 2013
Authors: Jay Chakraborty
However, the above method is strictly applicable for crystallographically untextured films exhibiting isotropic grain interactions [2].
For textured thin films, the most general approach of stress analysis is to use of the so-called X-ray stress factors involving the crystallographic orientation distribution function (ODF) with appropriate grain interaction model [2,3] which is cumbersome in practice.
For fiber textured specimen, in case of plane rotationally, symmetric state of stress the simplified sin2y law have been derived assuming Reuss type of grain interactions in the specimen.
Some of the major reasons are: (i) simultaneous presence of strong and sharp fiber texture in Ti films deposited for 15min. leads to small number of data points in the plots (Fig.2(c)) which makes the stress analysis unreliable; (ii) use of so-called X-ray diffraction elastic constants in stress analysis does not take into account of crystallographic texture in the films and thus can lead to serious errors in stress values; (iii) large data scatter in CGM plot (Fig.3(a)) may lead to erroneous stress values.
For textured thin films, the most general approach of stress analysis is to use of the so-called X-ray stress factors involving the crystallographic orientation distribution function (ODF) with appropriate grain interaction model [2,3] which is cumbersome in practice.
For fiber textured specimen, in case of plane rotationally, symmetric state of stress the simplified sin2y law have been derived assuming Reuss type of grain interactions in the specimen.
Some of the major reasons are: (i) simultaneous presence of strong and sharp fiber texture in Ti films deposited for 15min. leads to small number of data points in the plots (Fig.2(c)) which makes the stress analysis unreliable; (ii) use of so-called X-ray diffraction elastic constants in stress analysis does not take into account of crystallographic texture in the films and thus can lead to serious errors in stress values; (iii) large data scatter in CGM plot (Fig.3(a)) may lead to erroneous stress values.
Online since: June 2013
Authors: Alexey Anatolevich Vereschaka
In accordance with the selected model, the lost mass М of a tool was evaluated by the following formula: М = Ka·ρ·Fa· (Ј·σa/σp), where Ka is the adhesion coefficient (volume); ρ is the density of tool material; Ј=(NT+NM)Fa is the intensity of adhesion; NT, NM is, respectively, the number of active centres per unit of area of nominal contact Fa at thermal (NT) and mechanical (NM) activation; σa is the strength of bonds in adhesion centres; σp is the resistance of tool material to destruction.
Assisted synthesis of coatings when using technology has several advantages that are associated with mixing and alloying of deposited condensate by high-energy ions and are developed in the form of the following effects: • high entropic structures of increased hardness and heat resistance are formed at alloying of deposited condensate by various elements; • adhesion strength in the "substrate-coating" system increases significantly; • temperature of processes of the synthesis of coatings different in composition and structure decreases (up to 150-250°C), and that allows forming nano-dimensional grained structure (coagulation of grains is blocked) and significantly expands the range of materials, which may be coated.
It was found out that at the microhardness HV0.05 = 3.2 GPa, adhesion strength with the hard substrate Pcr = 140 N, the thickness of WRC of 3.9 μk, the grain size of 10-12 nm and thickness of subslayers of all three components (WC, IC, AC) of 20-25 nm obtained with UIMP = 30 kV, a tool, equipped with CP of T14K8 of TiN-TiCrAlN when turning steel 40X,provided maximum increase of wear resistance (up to 1.5-2 times) in comparison with the wear resistance of a tool of T14K8 with WRC of similar composition formed using of arc-PVD (fig.1).
Assisted synthesis of coatings when using technology has several advantages that are associated with mixing and alloying of deposited condensate by high-energy ions and are developed in the form of the following effects: • high entropic structures of increased hardness and heat resistance are formed at alloying of deposited condensate by various elements; • adhesion strength in the "substrate-coating" system increases significantly; • temperature of processes of the synthesis of coatings different in composition and structure decreases (up to 150-250°C), and that allows forming nano-dimensional grained structure (coagulation of grains is blocked) and significantly expands the range of materials, which may be coated.
It was found out that at the microhardness HV0.05 = 3.2 GPa, adhesion strength with the hard substrate Pcr = 140 N, the thickness of WRC of 3.9 μk, the grain size of 10-12 nm and thickness of subslayers of all three components (WC, IC, AC) of 20-25 nm obtained with UIMP = 30 kV, a tool, equipped with CP of T14K8 of TiN-TiCrAlN when turning steel 40X,provided maximum increase of wear resistance (up to 1.5-2 times) in comparison with the wear resistance of a tool of T14K8 with WRC of similar composition formed using of arc-PVD (fig.1).
Online since: March 2015
Authors: Magdalena Popczyk, Bożena Łosiewicz, Patrycja Osak
On the surface of the Ni-Co-P coating one can observe the fine-grained structure with a high number of interfaces between nickel and cobalt grains which may participate in the HER or the OER (Fig. 2a).
The SEM observations of the surface of the Ni-P coating reveals the very fine-grained structure and at some places small pores are visible (Fig. 2c).
The SEM observations of the surface of the Ni-P coating reveals the very fine-grained structure and at some places small pores are visible (Fig. 2c).
Online since: August 2008
Authors: Waldyr Ristow, Bernardo N. Nobrega, Tiago Eberle
Thus the typical MIM production of high-strength Ni-based superalloy components entails a
number of sequential, time-consuming and expensive manufacturing steps which hinder the overall
advantages of the entire MIM manufacturing route.
The higher temperature and longer sintering time caused considerable grain growth in lot A samples, which turned out somewhat oversintered.
Since the assintered density of these samples was already fairly high (98,49 ± 0,10% TD), it's concluded the gain in density due to HIPping was not enough to compensate for reductions in those mechanical properties which might have been caused by grain growth during HIPing. 5 As-sintered parts: Sint'd & HIP'd parts: Sint'd & heat treated parts: [1280 ºC / 2hr] [1185 ºC / 4 hr / 1000 bar] [1080 ºC / 8 hr - 700 ºC / 16 hr] 364 ± 8 HV10N 355 ± 3 HV10N 382 ± 9 HV10N As-sintered dog-bones: Sint'd & HIP'd dog-bones: Sint'd & heat treated dog-bones: [1280 ºC / 2hr] [1185 ºC / 4 hr / 1000 bar] [1080 ºC / 8 hr - 700 ºC / 16 hr] 0,2%PS UTS Є 0,2%PS UTS Є 0,2%PS UTS Є [MPa] [MPa] [%Lo] [MPa] [MPa] [%Lo] [MPa] [MPa] [%Lo] 800 1161 25
It's suggested HIP-induced grain growth caused these reductions despite the slight gain in density shown by the hot isostatically pressed parts. 5.
The higher temperature and longer sintering time caused considerable grain growth in lot A samples, which turned out somewhat oversintered.
Since the assintered density of these samples was already fairly high (98,49 ± 0,10% TD), it's concluded the gain in density due to HIPping was not enough to compensate for reductions in those mechanical properties which might have been caused by grain growth during HIPing. 5 As-sintered parts: Sint'd & HIP'd parts: Sint'd & heat treated parts: [1280 ºC / 2hr] [1185 ºC / 4 hr / 1000 bar] [1080 ºC / 8 hr - 700 ºC / 16 hr] 364 ± 8 HV10N 355 ± 3 HV10N 382 ± 9 HV10N As-sintered dog-bones: Sint'd & HIP'd dog-bones: Sint'd & heat treated dog-bones: [1280 ºC / 2hr] [1185 ºC / 4 hr / 1000 bar] [1080 ºC / 8 hr - 700 ºC / 16 hr] 0,2%PS UTS Є 0,2%PS UTS Є 0,2%PS UTS Є [MPa] [MPa] [%Lo] [MPa] [MPa] [%Lo] [MPa] [MPa] [%Lo] 800 1161 25
It's suggested HIP-induced grain growth caused these reductions despite the slight gain in density shown by the hot isostatically pressed parts. 5.
Online since: August 2008
Authors: G.K. Dey, A.P. Srivastava, Dinesh Srivastava, K.G. Suresh
These parameters were optimized after number of experiments to get amorphous ribbons.
This increase in the value of Hc may be accounted by the fact that for small grain sizes (< 100nm), Hc increases with increases in grain size [1].
So we conclude that as the sample is annealed at higher temperatures, the nanocrystalline grain size increases giving a higher value of Hc.
This increase in the value of Hc may be accounted by the fact that for small grain sizes (< 100nm), Hc increases with increases in grain size [1].
So we conclude that as the sample is annealed at higher temperatures, the nanocrystalline grain size increases giving a higher value of Hc.
Online since: February 2004
Authors: Atsushi Yamamoto, Koichi Kitajima, M. Sasai
The media developed for dry
barrel finishing is made of nylon resin mixed with abrasive grains.
� Turret rotation speed 0-240min -1 Rotation rate of barrel to turret -1 Distance between the turret center and the barrel center 160mm Barrel shape and number Equilateral octagon 㧔1.72L㧕4 Base side:46mm Length:165mm Barrel Turret Media Workpiece Workpiece� Ǿ3012mm, S45C(162,228HV), SUJ2(204,309,522,877HV) Media� Nylon6㧗Abrasives(A#320), ٌ44, 66mm Media charging ratio 20,50vol% Turret rotation speed 120,240min -1 Characteristic X-ray CrKǩ Target Cr Peak angle 2ǰ(deg) 156.4 Measuring method sin 2Ȁ Voltage (kV) 40 Current (mA) 40 Ȁ angle(deg) 0,7,15,22,30,37,45,52 Fixed time (sec) 10 Collimator (mm) 2.0 � Table 1 Specification of centrifugal barrel machine Fig.1 Centrifugal barrel finishing Table 2 Finishing conditions Table 3 Conditions of X-ray diffraction stress measurement Experimental Results and Discussion Influence of Finishing Conditions on Finishing Characteristics.
This is considered to be because the intrusion depth of the abrasive grain on the media surface to the workpiece surface at the collision of media to the workpiece decreases with the increase of the workpiece hardness.� Figure 9 shows the relationship between the workpiece hardness and the surface roughness under the same finishing conditions as shown in Fig.8.
Consequently, the change of the intrusion depth of the abrasive grain on media surface caused by the change of the contact force of the media to the workpiece becomes small as the intrusion depth decrease, and the surface roughness becomes small.�� Figure 10 shows the relationship between the workpiece hardness and the edge radius for one hour of finishing time under the same finishing conditions as in Fig.8.�6he edge radius decreases as the workpiece hardness increases.
� Turret rotation speed 0-240min -1 Rotation rate of barrel to turret -1 Distance between the turret center and the barrel center 160mm Barrel shape and number Equilateral octagon 㧔1.72L㧕4 Base side:46mm Length:165mm Barrel Turret Media Workpiece Workpiece� Ǿ3012mm, S45C(162,228HV), SUJ2(204,309,522,877HV) Media� Nylon6㧗Abrasives(A#320), ٌ44, 66mm Media charging ratio 20,50vol% Turret rotation speed 120,240min -1 Characteristic X-ray CrKǩ Target Cr Peak angle 2ǰ(deg) 156.4 Measuring method sin 2Ȁ Voltage (kV) 40 Current (mA) 40 Ȁ angle(deg) 0,7,15,22,30,37,45,52 Fixed time (sec) 10 Collimator (mm) 2.0 � Table 1 Specification of centrifugal barrel machine Fig.1 Centrifugal barrel finishing Table 2 Finishing conditions Table 3 Conditions of X-ray diffraction stress measurement Experimental Results and Discussion Influence of Finishing Conditions on Finishing Characteristics.
This is considered to be because the intrusion depth of the abrasive grain on the media surface to the workpiece surface at the collision of media to the workpiece decreases with the increase of the workpiece hardness.� Figure 9 shows the relationship between the workpiece hardness and the surface roughness under the same finishing conditions as shown in Fig.8.
Consequently, the change of the intrusion depth of the abrasive grain on media surface caused by the change of the contact force of the media to the workpiece becomes small as the intrusion depth decrease, and the surface roughness becomes small.�� Figure 10 shows the relationship between the workpiece hardness and the edge radius for one hour of finishing time under the same finishing conditions as in Fig.8.�6he edge radius decreases as the workpiece hardness increases.
Online since: December 2016
Authors: Ichiro Shimizu
It had rather isotropic texture as shown in Fig. 1(a) obtained by electro backscatter diffraction (EBSD) measurement and had relatively large average grain size of about 180 μm.
Meanwhile, the extruded alloy had small average grain size of about 60 μm and had strong texture, of which the basal plane of hcp structure was about parallel to the extruded direction as shown in Fig 1(b).
Owing to the arrangement of the heaters and the thermocouple, the compressive displacement was converted from the number of pulse using the pre-determined compensation curve.
The EBSD measurement was performed only on the cast alloy because the large grain size is preferable to distinguish twinning from slip lines.
Meanwhile, the extruded alloy had small average grain size of about 60 μm and had strong texture, of which the basal plane of hcp structure was about parallel to the extruded direction as shown in Fig 1(b).
Owing to the arrangement of the heaters and the thermocouple, the compressive displacement was converted from the number of pulse using the pre-determined compensation curve.
The EBSD measurement was performed only on the cast alloy because the large grain size is preferable to distinguish twinning from slip lines.
Online since: September 2012
Authors: Manabu Iwai, Kiyoshi Suzuki, Shinichi Ninomiya, Yuya Kazui
The size of the diamond abrasive (non conductive) used was SD700 mesh and the concentration was 125 (grain volume percentage: 31%).
The average grain size was 10µm for both types of PCD.
Though details are not shown on the results of the trueing using a vertical truer, it will be worth describing that the electrically conductive vitrified bonded wheel could be trued with extremely high efficiency requiring far less number of passes for correcting the wheel deviation, namely only one tenth of that required by the metal bonded wheel.
Fig.3 Normal grinding force at standard grinding Table 1 Experimental device and conditions Conductive vitrified bonded wheel •Standard diamond abrasive wheel •Conductive diamond abrasive wheel SD700, Conc.125 (f100mm×t5mm) Machine •NC surface grinding machine (NSP-50, Nachi) •Spindle: Air static spindle (Toshiba Machine) •Discharge power source (SUE-87, Sodick) PCD workpiece •Conventional PCD (C-PCD, 5mm×8mm) •Electrically conductive PCD (EC-PCD, 5mm×8mm) Diamond grain size: 10µm, Content: ≠90% Grinding conditions VS=40m/s, VW=0.1m/min, a=1µm, b=2mm, l=5mm Surface plunge grinding Discharge conditions ui=60V, iP=6A, te=4µs, to=10µs Working fluid Water soluble grinding fluid (NK-Z, 2%, Noritake) Results of the EDM Assisted Grinding Characteristics in the Standard Grinding.
The average grain size was 10µm for both types of PCD.
Though details are not shown on the results of the trueing using a vertical truer, it will be worth describing that the electrically conductive vitrified bonded wheel could be trued with extremely high efficiency requiring far less number of passes for correcting the wheel deviation, namely only one tenth of that required by the metal bonded wheel.
Fig.3 Normal grinding force at standard grinding Table 1 Experimental device and conditions Conductive vitrified bonded wheel •Standard diamond abrasive wheel •Conductive diamond abrasive wheel SD700, Conc.125 (f100mm×t5mm) Machine •NC surface grinding machine (NSP-50, Nachi) •Spindle: Air static spindle (Toshiba Machine) •Discharge power source (SUE-87, Sodick) PCD workpiece •Conventional PCD (C-PCD, 5mm×8mm) •Electrically conductive PCD (EC-PCD, 5mm×8mm) Diamond grain size: 10µm, Content: ≠90% Grinding conditions VS=40m/s, VW=0.1m/min, a=1µm, b=2mm, l=5mm Surface plunge grinding Discharge conditions ui=60V, iP=6A, te=4µs, to=10µs Working fluid Water soluble grinding fluid (NK-Z, 2%, Noritake) Results of the EDM Assisted Grinding Characteristics in the Standard Grinding.