In coated tools, the grain boundaries and coating layers are areas of intense energy dissipation, which hardens the coating material by increasing its toughness and its resistance to the formation ...and development of cracks. An increase in the efficiency of the coatings was achieved by applying nano-dispersed multilayer composite structure. This paper proposes using nano-scale multilayer composite coating based on
TiN-CrN
compound to improve thermal stability, where barrier layers based on
ZrNbN
have been introduced. The
ZrNbN
barrier does not interact with
TiN
and
CrN
at temperatures around 1000 °C. The influence of process parameters of the filtered cathodic vacuum arc deposition on the composition, structure and properties of the coatings based on variation of
TiAlN-ZrNbN-CrN
was analysed. The results presented here show that the hardness of the developed coatings was as high as 38 GPa. Subsequently, the carbide tools used in this study with the new coatings had an increased lifetime of 1.5–2.0 times compared to tools with commercial coatings. The coated carbide tools were tested in longitudinal turning and face milling titanium and nickel alloys.
In machining, the tool life is one of the limiting criteria in the process; therefore, the development of wear-resistant material for the cutting tools is imperative. This paper presents a ...methodological approach to the design of nano-scale multilayered-composite coatings for cutting tools. A plasma-enhanced technology of filtered cathodic vacuum-arc deposition is used to coat the tools, which significantly extends the operational life of the cutting tools. Here, a three-layered architecture of coatings is proposed and each layer has a specific function. The engineered structural layers allowed for optimum combination of a high adhesion strength with the tool substrate and a minimum adhesion of the work material to the tool surface. The coating process is presented here alongside with the technological role of the layers. A study of the effect of the developed nano-scale multilayer composite coatings on the rates of tool wear was undertaken, and results were compared with the wear rates of uncoated and standard coatings. The results of a wide range experimental work are given in terms of flank wear and tool life for various machining conditions.
Aim
Climate‐driven trends in environmental processes and their effect on marine ecosystems remain poorly understood despite an obvious decrease in marine biological resources which undergo changes in ...stock size mediated by phyto‐ and mesoplankton. A mesoplankton multiannual dataset is one of the best tools to elucidate general trends in marine ecosystems.
Location
Oligo‐ and mesotrophic waters of the Central Atlantic.
Time Period
1950–2016.
Major Taxa Studied
Chaetognatha, Cnidaria, Crustacea, Mollusca.
Methods
Wet mesoplankton biomass (B) values were estimated in 1159 mesoplankton (animals 0.5–30.0 mm long) samples collected in the open ocean epipelagic (0–200 m) in 1950–2016. We ran Generalized Linear Mixed Models and analysed general trends in B, in satellite‐derived surface chlorophyll (Chl, as a proxy of phytoplankton biomass in 1998–2015), and surface temperature (SST, NCEP/NCAR reanalysis, 1948–2015). We further compared the multiannual trends in B, SST, Chl and in space of the oligotrophic and mesotrophic Chl contours in selected regions and in the whole Central Atlantic.
Results
We showed a statistically significant decline of B within the whole Central Atlantic (9‐fold during 1950–2016) and within each of the three selected regions. These trends were always coupled with other statistically significant effects: increase of SST, decline of Chl, expansion of Chl‐depleted areas and shrinkage of Chl‐enriched areas.
Main Conclusions
The results unveil the following causal relationship in the Central Atlantic: SST increase → strengthening of stratification → Chl decline—expansion of low‐productive areas → B decrease, which, along with existing prognostic climate models, suggests future mesoplankton decline in the Central Tropical Atlantic. The decline in Chl and B is expected to amplify decrease of higher trophic levels biomass and thus to result in changes in the marine food webs. Observed changes in biomass and production will imply direct repercussions for world fisheries and other services provided by Ocean.
This article presents the work on wear-resistance coatings (WRC), formed on the working surfaces of HSS tools, in order to increase their efficiency. The wear-resistant complex includes nitride ...layer, which increases the plastic strength of the HSS tool cutting wedge and cutting tool wear resistance, as well as a three-layer nano-structured composite coating that increases tool life. The equipment for the processes of ion nitriding in the gas plasma and the formation of nano-structured multi-layer composite coatings in the filtered metal-gas plasma cathode vacuum arc discharge has been developed. Particular attention was paid to the regularities in the formation of the nitride layer and optimization of its parameters and structure, together with the study of the properties and structure of functional coating layers, depending on the parameters of the deposition process. The parameters of the combined cathodic vacuum arc processing (CCVAP), provides minimum intensity of tool wear during the cutting tests. Sample of coated tools were used to conduct a certification of the developed WRC. This allowed determining the optimal parameters WRC that provided the maximum increase in tool life for a variety of cutting conditions. The outcomes are compared with uncoated HSS tool and standard commercial coatings.
The functional role of nanostructured multilayer composite coatings (NMCC) deposited on the operating surfaces of replaceable faceted cutting inserts (CI) from cutting ceramics based on aluminum ...oxides with additives of titanium carbides is studied. It is shown that the developed NMCC not only raise substantially the endurance of the ceramic tools under high-speed dry treatment of quenched steels but also improve the quality and accuracy of processing of the parts and the ecological parameters of the cutting process.
The work “The Mechanism of Wear Process of Cobalt-Carbide” shows the result of studying cemented carbide when machining refractory alloys based on chromium (X65HBΦT) and nickel (XH77TУP). The ...conducted research has shown that the machining of chromium-based alloy with a more heat-resistant process of the wear of the carbide inserts with or without a nanoscale coating occurs less intensively than for the tool wear process in the machining of Ni alloy It is established that this effect is connected with different crystal structures, phase contents, and properties of the heat-resistant alloys in question.
The NEMO-3 results for the double-
β
decay of
150
Nd to the 0
1
+
and 2
1
+
excited states of
150
Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope
150
Nd are used in the ...analysis. The signal of the
2
ν
β
β
transition to the 0
1
+
excited state is detected with a statistical significance exceeding 5
σ
. The half-life is measured to be
T
1
/
2
2
ν
β
β
(
0
1
+
)
=
1
.
11
-
0.14
+
0.19
stat
-
0.15
+
0.17
syst
×
10
20
year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the
2
ν
β
β
decay to the 2
1
+
level the limit is
T
1
/
2
2
ν
β
β
(
2
1
+
)
>
2.42
×
10
20
year
. The limits on the
0
ν
β
β
decay to the 0
1
+
and 2
1
+
levels of
150
Sm are significantly improved to
T
1
/
2
0
ν
β
β
(
0
1
+
)
>
1.36
×
10
22
year
and
T
1
/
2
0
ν
β
β
(
2
1
+
)
>
1.26
×
10
22
year
.
The paper presents the results of studies of the cutting properties and wear mechanism of the edge cutting tool equipped with replaceable indexable inserts made of cutting ceramic with nanoscale ...multilayer composite coatings when cutting hardened steel. It has been shown that applying the latter allows one to tune the contact processes based on the changes in friction and lengths of dense and complete contacts between the chip and the rake face of the cutting tools, thereby reducing normal contact strains and the probability of macro- and microbrittle fracture in the contact areas of the tool.
The influence of the hard-alloy substrate and the composite coatings of a tool on its wear resistance in the machining of high-temperature chromium alloys is investigated. The effectiveness of the ...coated hardalloy tool is determined by the properties of the hard alloy and the coatings. For hard alloys characterized by relatively low strength and crack resistance, the coatings prove ineffective, on account of the brittle failure of the substrate and the consequent destruction of the coating. On alloys with low thermal stability, the coatings are ineffective on account of weakening of the binder at the high temperatures associated with machining. It makes sense to use a hard alloy with mechanical properties such that the coating may operate effectively. Better properties are not needed.
Abstract The NEMO-3 results for the double- $$\beta $$ β decay of $$^{150}$$ 150 Nd to the 0 $$^+_1$$ 1 + and 2 $$^+_1$$ 1 + excited states of $$^{150}$$ 150 Sm are reported. The data recorded during ...5.25 year with 36.6 g of the isotope $$^{150}$$ 150 Nd are used in the analysis. The signal of the $$2\nu \beta \beta $$ 2 ν β β transition to the 0 $$^+_1$$ 1 + excited state is detected with a statistical significance exceeding 5 $$\sigma $$ σ . The half-life is measured to be $$T_{1/2}^{2\nu \beta \beta }(0^+_1) = \left 1.11 ^{+0.19}_{-0.14} \,\left( \hbox {stat}\right) ^{+0.17}_{-0.15}\,\left( \hbox {syst}\right) \right \times 10^{20}$$ T 1 / 2 2 ν β β ( 0 1 + ) = 1 . 11 - 0.14 + 0.19 stat - 0.15 + 0.17 syst × 10 20 year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the $$2\nu \beta \beta $$ 2 ν β β decay to the 2 $$^+_1$$ 1 + level the limit is $$T^{2\nu \beta \beta }_{1/2}(2^+_1) > 2.42 \times 10^{20}~\hbox {year}$$ T 1 / 2 2 ν β β ( 2 1 + ) > 2.42 × 10 20 year . The limits on the $$0\nu \beta \beta $$ 0 ν β β decay to the 0 $$^+_1$$ 1 + and 2 $$^+_1$$ 1 + levels of $$^{150}$$ 150 Sm are significantly improved to $$T_{1/2}^{0\nu \beta \beta }(0^+_1) > 1.36 \times 10^{22}~\hbox {year}$$ T 1 / 2 0 ν β β ( 0 1 + ) > 1.36 × 10 22 year and $$T_{1/2}^{0\nu \beta \beta }(2^+_1) > 1.26 \times 10^{22}~\hbox {year}$$ T 1 / 2 0 ν β β ( 2 1 + ) > 1.26 × 10 22 year .
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